Ieee standard for the electrical protection of communication facilities serving electric supply loca by Jinghua

IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

IEEE Power and Energy Society

Sponsored by the Power System Communications Committee

IEEE 3 Park Avenue New York, NY 10016-5997 USA

IEEE Std 487.3â&#x201E;¢-2014

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IEEE Std 487.3â&#x201E;˘-2014

IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities Sponsor

Power System Communications Committee of the

IEEE Power and Energy Society Approved 15 May 2014

IEEE-SA Standards Board

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Abstract: Safe and reliable methods for the electrical protection of telecommunication facilities serving electric supply locations through the use of metallic wire-line components in part of the telecommunication circuit and optical fiber systems in the remainder of the telecommunication circuit are presented in this standard. Hybrid applications have an equipment junction between the metallic wire-line and the fiber cable, i.e., a wire-line–fiber cable junction (CFJ). Keywords: CFJ, copper-fiber junction, electric power stations, electric supply locations, electrical protection, fiber-optic systems, ground potential rise, high-voltage environment, IEEE 487.3™, optical fiber systems •

The Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue, New York, NY 10016-5997, USA Copyright © 2014 by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published 18 August 2014. Printed in the United States of America. IEEE is a registered trademark in the U.S. Patent & Trademark Office, owned by The Institute of Electrical and Electronics Engineers, Incorporated. National Electrical Safety Code and NESC are both registered trademarks and service marks of The Institute of Electrical and Electronics Engineers, Inc. National Electrical Code and NEC are both registered trademarks of the National Fire Protection Association, Inc. PDF: Print:

ISBN 978-0-7381-9155-3 ISBN 978-0-7831-9156-0

STD98682 STDPD98682

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Participants At the time this IEEE standard was completed, the Wire-Line Working Group had the following membership: Percy E Pool, Co-Chair and Technical Editor Larry Young, Co-Chair and Secretary Steven Blume Joe Boyles Timothy Conser Bhimesh Dahal Jean de Seve

Ernest Duckworth John Fuller Ernest Gallo Dave Hartmann

Dan Jendek Richard Knight Randall Mears Mark Tirio Thomas Vo

The Wire-Line SC acknowledges the contributions of the following members of SC5: Al Bonnyman

Bill Byrd Delavar Khomarlou

Robert Whatley

The following members of the individual balloting committee voted on this standard. Balloters may have voted for approval, disapproval, or abstention.

William Ackerman R. Baysden Steven Blume Joe Boyles Gustavo Brunello Timothy Conser Michael Dood Douglas Dorr Randall Dotson Ernest Duckworth Sourav Dutta John Fuller Doaa Galal Timothy Gauthier Frank Gerleve

Jalal Gohari Randall Groves Innocent Kamwa Yuri Khersonsky Richard Knight Jim Kulchisky Lawrenc Long William McCoy Joseph Mears John Miller Jose Morales Jerry Murphy Michael Newman Gary Nissen

James Oâ&#x20AC;&#x2122;Brien Lorraine Padden Percy Pool Craig Preuss Charles Rogers Jesse Rorabaugh Bartien Sayogo Veselin Skendzic Michael Swearingen David Tepen Mark Tirio John Vergis Kenneth White James Wilson Larry Young

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When the IEEE-SA Standards Board approved this standard on 15 May 2014, it had the following membership: John Kulick, Chair Jon Walter Rosdahl, Vice-chair Richard H. Hulett, Past Chair Konstantinos Karachalios, Secretary Peter Balma Farooq Bari Ted Burse Clint Chaplain Stephen Dukes Jean-Phillippe Faure Gary Hoffman

Michael Janezic Jeffrey Katz Joseph L. Koepfinger* David Law Hung Ling Oleg Logvinov Ted Olsen Glenn Parsons

Ron Peterson Adrian Stephens Peter Sutherland Yatin Trivedi Phil Winston Don Wright Yu Yuan

*Member Emeritus

Also included are the following nonvoting IEEE-SA Standards Board liaisons: Richard DeBlasio, DOE Representative Michael Janezic, NIST Representative Don Messina IEEE-SA Content Publishing Erin Spiewak IEEE-SA Standards Technical Community

vii

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Introduction This introduction is not part of IEEE Std 487.3-2014, IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities.

Wire-line telecommunication facilities serving electric supply locations often require special high-voltage protection (HVP) against the effects of fault-produced ground potential rise (GPR) or induced voltages, or both. Some of the telecommunication services are used for control and protective relaying purposes and may be called on to perform critical operations at times of power system faults. Even when critical services are not involved, special HVP may be required for both personnel safety and plant protection at times of power system faults. Effective protection of any wire-line telecommunication circuit requires coordinated protection on all circuits provided over the same telecommunication cable. Some electrical environments, collectively called electric supply locations, require the application of unique electrical protection techniques because of their special nature. One such environment is the electric power station or substation. Another is at or near power line transmission and distribution structures such as towers or poles. Such structures often provide a convenient site for the location of wireless, personal communications service, and cellular antennas and their associated electronic equipment that is served by a link to the wired telecommunications network. This standard describes applications consisting of both metallic cables and optical fiber cables, i.e., hybrid facilities or, in other words, applications using metallic wire-line components in part of the telecommunication circuit and optical fiber cables in the remainder of the telecommunication circuit. Hybrid applications have an equipment junction between the metallic wire-line and the optical fiber cable, i.e., a wire-line–fiber cable junction (CFJ). This standard also describes the special case when the CFJ is placed inside the zone of influence (ZOI). For applications consisting entirely of optical fiber cables, the user is referred to IEEE Std 487.2™. a This standard presents workable methods for the electrical protection of wire-line telecommunication circuits serving electric supply locations through the use of hybrid facilities. This project is part of a reorganization of the IEEE 487™ documentation in which the main document is broken down into a family of related documents (i.e., dot-series) segregated on the basis of technology:      

IEEE Std 487™ for general considerations IEEE Std 487.1™ for applications using on-grid isolation equipment IEEE Std 487.2™ for applications consisting entirely of optical fiber cables IEEE Std 487.3™ for applications of hybrid facilities where part of the circuit is on metallic wireline and the remainder of the circuit is on optical fiber cable IEEE Std 487.4™ for applications using neutralizing transformers IEEE Std 487.5™ for applications using isolation transformers

This standard has been prepared by the Wire-Line Subcommittee of the Power System Communications Committee of the IEEE Power and Energy Society, and it represents the consensus of both power and telecommunications engineers. This standard, along with IEEE Std 487.2, replaces, in its entirety, the recommended practice IEEE Std 1590™-2009, which covered electrical protection of communication facilities serving electric supply locations using optical fiber systems.

Information about normative references can be found in Clause 2.

viii

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Contents 1. Overview .................................................................................................................................................... 1 1.1 Scope ................................................................................................................................................... 2 1.2 Purpose ................................................................................................................................................ 2 2. Normative references.................................................................................................................................. 2 3. Definitions, abbreviations and acronyms ................................................................................................... 3 3.1 Definitions ........................................................................................................................................... 3 3.2 Abbreviations and acronyms ............................................................................................................... 4 4. Overview of telecommunications service to electric supply locations ....................................................... 5 4.1 Electric power stations......................................................................................................................... 6 4.2 Wireless service sites ........................................................................................................................... 6 4.3 Service via metallic wire-line facilities................................................................................................ 6 4.4 Service via optical fiber facilities ........................................................................................................ 6 4.5 Service via microwave systems ........................................................................................................... 7 4.6 Responsibilities .................................................................................................................................... 7 5. Hybrid fiber-optic isolation systems ........................................................................................................... 7 5.1 Topologies for hybrid optical fiber isolation systems .......................................................................... 8 6. Telecommunications service to electric supply locations ......................................................................... 11 6.1 Voltage protection levels ................................................................................................................... 12 6.2 Locations at or near high-voltage towers or poles ............................................................................. 13 6.3 Electrical protection considerations for telecommunications outside plant serving high-voltage tower and pole sites ................................................................................................................................. 13 6.4 Electrical protection measures ........................................................................................................... 14 6.5 Typical grounding.............................................................................................................................. 14 7. Telecommunications service to electric supply locations—recommendations......................................... 16 7.1 GPR-related protection considerations .............................................................................................. 16 7.2 Induction-related protection considerations ....................................................................................... 16 7.3 Benefits of all-dielectric cables.......................................................................................................... 16 8. Design recommendations for CFJ installations ........................................................................................ 17 8.1 CFJ at electric power stations ............................................................................................................ 17 8.2 CFJ located outside the ZOI of an electric supply location ............................................................... 18 8.3 CFJ located within the ZOI of an electric supply location................................................................. 18 8.4 Conditional deployment of CFJ with electronics or pair protection that requires grounding by design.................................................................................................................................................. 19 8.5 Conditional deployment of CFJ with electronics or pair protection that does not require grounding by design ................................................................................................................................ 21 9. Powering arrangements at electric supply locations ................................................................................. 23 9.1 Typical ac power service to wireless locations at power line towers or poles ................................... 24 9.2 Distribution transformers ................................................................................................................... 24 9.3 Electrostatic coupling ........................................................................................................................ 24 9.4 Engine generating units ..................................................................................................................... 25 10. Typical dc powering arrangements at OEI and CFJ ............................................................................... 25 10.1 Wire-line–fiber cable junction (CFJ) ............................................................................................... 27 ix

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10.2 Remote end and OEI........................................................................................................................ 31 11. Construction concerns and general recommendations ............................................................................ 31 11.1 Existing facilities ............................................................................................................................. 31 11.2 Locating buried all-dielectric optical fiber cable ............................................................................. 32 12. Installation and inspection considerations .............................................................................................. 32 12.1 Installation considerations ............................................................................................................... 32 12.2 Inspection considerations................................................................................................................. 32 13. Safety ...................................................................................................................................................... 32 13.1 General safety considerations .......................................................................................................... 32 13.2 Electrical safety ............................................................................................................................... 33 13.3 Radio frequency (RF) safety awareness .......................................................................................... 33 Annex A (informative) Bibliography ........................................................................................................... 35 Annex B (informative) Locating buried cables ............................................................................................ 38 B.1 Overview ........................................................................................................................................... 38 B.2 Locating methods .............................................................................................................................. 38 B.3 Benefits ............................................................................................................................................. 39 B.4 Recommendations ............................................................................................................................. 39 B.5 Provisions for locating buried all-dielectric optical fiber cable ........................................................ 40

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IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities IMPORTANT NOTICE: IEEE Standards documents are not intended to ensure safety, security, health, or environmental protection, or ensure against interference with or from other devices or networks. Implementers of IEEE Standards documents are responsible for determining and complying with all appropriate safety, security, environmental, health, and interference protection practices and all applicable laws and regulations. This IEEE document is made available for use subject to important notices and legal disclaimers. These notices and disclaimers appear in all publications containing this document and may be found under the heading “Important Notice” or “Important Notices and Disclaimers Concerning IEEE Documents.” They can also be obtained on request from IEEE or viewed at http://standards.ieee.org/IPR/disclaimers.html.

1. Overview Wire-line telecommunication facilities serving electric supply locations often require special high-voltage protection (HVP) against the effects of fault-produced ground potential rise (GPR) or induced voltages, or both. Some of the telecommunication services are used for control and protective relaying purposes and may be called on to perform critical operations at times of power system faults. This requirement presents a major challenge in the design and protection of the telecommunication system because power system faults can result in the introduction of interfering voltages and currents into the telecommunication circuit at the very time when the circuit is most urgently required to perform its function. Even when critical services are not involved, special HVP may be required for both personnel safety and plant protection at times of power system faults. Effective protection of any wire-line telecommunication circuit requires coordinated protection on all circuits provided over the same telecommunication cable. This standard does not include optical fiber cables that are used entirely within electric power substations, as this is covered by IEEE Std 525™[B27]. 1

The numbers in brackets correspond to the numbers of the bibliography in Annex A.

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

1.1 Scope This standard presents engineering design procedures for the electrical protection of telecommunication facilities serving electric supply locations through the use of metallic wire-line components in part of the telecommunication circuit and optical fiber systems in the remainder of the telecommunication circuit. Other telecommunication alternatives such as radio and microwave systems are excluded from this document.

1.2 Purpose This standard presents workable methods that can be used with greater reliability to improve the electrical protection of telecommunication facilities serving electric supply locations through the use of metallic wire-line components in part of the telecommunication circuit and optical fiber systems in the remainder of the telecommunication circuit. Hybrid applications have an equipment junction between the metallic wireline and the fiber cable, i.e., a wire-line–fiber cable junction (CFJ).

2. Normative references The following referenced documents are indispensable for the application of this document (i.e., they must be understood and used; therefore, each referenced document is cited in text and its relationship to this document is explained). For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies. Accredited Standards Committee C2, National Electrical Safety Code® (NESC®). 2, 3 IEEE Std 80™, IEEE Guide for Safety in AC Substation Grounding. 4, 5 IEEE Std 367™, IEEE Recommended Practice for Determining the Electric Power Station Ground Potential Rise and Induced Voltage from a Power Fault. IEEE Std 487™, IEEE Recommended Practice for the Protection of Wire-line Communication Facilities Serving Electric Supply Locations. 6 IEEE Std 487.1™, IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of On-Grid Isolation Equipment. IEEE Std 487.2™, IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Optical Fiber Systems. NFPA 70, National Electrical Code® (NEC®). 7, 8

The NESC is available from The Institute of Electrical and Electronics Engineers (http://standards.ieee.org/). National Electrical Safety Code and NESC are both registered trademarks and service marks of The Institute of Electrical and Electronics Engineers, Inc. 4 IEEE publications are available from The Institute of Electrical and Electronics Engineers (http://standards.ieee.org/). 5 The IEEE standards or products referred to in this clause are trademarks of The Institute of Electrical and Electronics Engineers, Inc. 6 There is an approved PAR to revise Std 487 and re-title it to “IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations—General Considerations.” 7 The NEC is published by the National Fire Protection Association (http://www.nfpa.org/). 8 National Electrical Code and NEC are both registered trademarks of the National Fire Protection Association, Inc. 3

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

3. Definitions, abbreviations and acronyms 3.1 Definitions For this document, the following terms and definitions apply. The IEEE Standards Dictionary Online should be consulted for terms not defined in this clause. 9 all-dielectric: An optical fiber cable construction having no metallic or conductive components. base transceiver station (BTS): A unit or component of a wireless service site consisting of all radio transmission and receiving equipment. counterpoise: A conductor or system of conductors located on, above, or most frequently below the surface of the earth and connected to the grounding system of towers or poles. electric power station: A substation or generating station. electric supply locations: Any building, separate space, or site in which electric supply equipment is located that may be subjected to the effects of ground potential rise (GPR) from power system fault currents. This definition includes generation, transformation, conversion, switching, and delivery facilities. facility interface point (FIP): The splice point for general use cable to dedicated cable. The FIP may be located anywhere in the circuit. ground potential rise (GPR): The electrical potential that a ground electrode (or grounding system) may attain relative to a distant grounding point. NOTE 1—Under normal conditions, the grounded electrical equipment operates at near zero ground potential. In other words, the potential of a grounded neutral conductor is nearly identical to the potential of remote earth. During a ground fault, the portion of fault current that is conducted by an electric supply location grounding grid into the earth causes the rise of the grid potential with respect to remote earth. 10 NOTE 2—See IEEE Std 367 for the method of calculating GPR. 11

high-voltage: Describing power lines carrying a voltage higher than 34.6 kV phase to ground. high-voltage environment (HVE): A location requiring caution because it may experience a ground potential rise (GPR) from power line fault currents and/or lightning strike energy. high-voltage interface (HVI): Protective apparatus that provides electrical isolation of wire-line telecommunications conductive paths. metallic member: A non-communications metallic cable component such as a shield, vapor barrier, locating tracer wire, or strength member. optical fiber: A thin glass or plastic strand designed for the transmission of light, typically by internal reflections. optical fiber cable: A telecommunications cable containing optical fibers as the primary transmission medium. The cable may contain metallic or nonmetallic members and metallic pairs. 9 The IEEE Standards Dictionary Online subscription are available at http://www.ieee.org/portal/innovate/products/standard/standards_dictionary.html. 10 Notes in text, tables, and figures are given for information only and do not contain requirements needed to implement this standard. 11 Information on normative references can be found in Clause 2.

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

outside plant: All cables and wires (whether aerial, buried, or underground) in a telecommunications network that are located outside buildings. Outside plant includes associated terminals, closures, pedestals, and supporting structures such as poles. optical electrical interface (OEI): The interface point and associated equipment for converting optical fiber transport to a metallic circuit. An OEI is typically paired with a wire-line–fiber cable junction (CFJ) on the opposite end of the fiber facility. personal communications service: A set of capabilities that allows some combination of terminal mobility, personal mobility, and service profile management. remote drainage location (RDL): A designated point on the dedicated metallic cable (often at the splice to the general use cable) located outside the ground potential rise (GPR) zone of influence (ZOI), having local ground reference. Protection and/or shunting devices may be located here on some applications. wireless: A form of telecommunications utilizing radio links to deliver voice, data, and other information. wireless service provider: A company that provides wireless telecommunication service to customers, e.g., cellular service providers, wireless data providers, radio common carriers, paging companies. wire-line: Describing a network that uses metallic (e.g., copper, steel, aluminum) wire conductors for telecommunications. wire-line–fiber cable junction (CFJ): The interface point and associated equipment for converting wireline transport to optical fiber transport. A CFJ is typically paired with an optical electrical interface (OEI) on the opposite end of the optical fiber facility. zone of influence (ZOI): An area around a ground electrode bounded by points of specified equal potential resulting from the voltage drop through the earth between the ground electrode and remote earth.

3.2 Abbreviations and acronyms ADSS

all-dielectric self-supporting

AWG

American wire gauge

BIL

basic impulse insulation level

BTS

base transceiver station

CATV

cable television

CFJ

wire-line (e.g., copper, steel, aluminum) to fiber cable junction

central office

DGPS

Differential Global Positioning System

DS-1

digital service at 1.544 Mb/s

DS-3

digital service at 44.736 Mb/s

EMI

electromagnetic induction

FIP

facility interface point 4

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

FTTx

fiber to the x (where x may be home, curb, neighborhood, etc.)

GPR

ground potential rise

GPS

Global Positioning System

HVE

high-voltage environment

HVP

high-voltage protection

MGN

multigrounded neutral

MOV

metal oxide varistor

MPE

maximum permissible exposure

NCTE

network channel terminating equipment

OEI

optical electrical interface

OGC

overhead grounding conductor

OGW

overhead ground wire

OPGW

optical ground wire

OSHA

Occupational Safety and Health Administration

PoF

power-over-fiber

PPE

personal protective equipment

PVC

polyvinyl chloride

RDL

remote drainage location

radio frequency

rms

root-mean-square

SCADA

supervisory control and data acquisition

SPO

service performance objective

UPS

uninterruptible power source

ZOI

zone of influence

4. Overview of telecommunications service to electric supply locations Two different electric supply locations or high-voltage environments (HVEs) are described in 4.1 and 4.2. The telecommunications facility may be a metallic wire-line cable, an optical fiber cable, wireless system, or a microwave system.

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

4.1 Electric power stations Telecommunications service to electric power stations is provided via a link that connects the telecommunications equipment located at or near the electric power station with the central office (CO) or switching center of the telecommunications service provider. Telecommunications services to an electric power station include a large variety of types (see IEEE Std 487). Refer to IEEE Std 789™ [B28] for typical specifications for telecommunication cables at electric supply locations.

4.2 Wireless service sites Wireless service sites are established at a variety of locations including at or near power line transmission and distribution structures such as towers or poles. These locations typically have a telecommunications facility that connects the associated electronic equipment, or base transceiver station (BTS), with the wireless switching center, either directly or through a telecommunications CO (see Ashdown et al. [B1] and Bellarmine and Lee [B4]). Telecommunication services to a wireless service site have often been provided by DS-1 or DS-3 type circuits (i.e., digital service at 1.544 Mb/s or at 44.736 Mb/s, respectively). Newer services may include based services based on Internet Protocol (IP) such as Ethernet, multi-protocol label switching (MPLS), or similar protocols. Refer to IEEE Std 789 [B28] for typical specifications for telecommunication cables at electric supply locations.

4.3 Service via metallic wire-line facilities When the telecommunications facility consists solely of a metallic wire-line cable, then IEEE Std 487 and IEEE Std 487.1 are used to determine the level of electrical protection needed at the electric supply location.

4.4 Service via optical fiber facilities Ground potential rise (GPR) and induction at the electric supply location may exceed the capabilities of the metallic wire-line facility. In an electric supply location environment, an optical fiber system may be viewed as both a telecommunications transport medium and a high-voltage interface (HVI) within the HVE. Refer to IEEE Std 487.2 for applications based entirely on optical fiber cables. Optical ground wire (OPGW) (see IEEE Std 1138™-1994 [B29]), all-dielectric self-supporting (ADSS) (see IEEE Std 1222™-2004 [B30]), and wrapped fiber (see IEEE Std 1594™ [B33]) are three examples of optical fiber cables installed on high-voltage transmission lines. These cables form the backbone of a smart utility grid as they carry critical data for switching and load decisions based on line losses, telemetry, and customer or end-point loading information. These optical fiber cables can be part of utility private fiber network or be revenue-generating as part of a utility commercial network. Typical configurations include, but are not limited, to the following:    

Interconnection of substations (e.g. transformer, switching, or distribution stations) via serving transmission lines Interconnection of a substation to a generating station Connection of a utility substation to a third party’s generation facility Connection of a utility facility to a commercial entity (carrier or ISP) demarcation point 6

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

   

Connection of fibers to the CFJ Connection of distributed generators to substations (protection and telemetry) Connection of industrial or wholesale load centers to serving stations (protection and telemetry) Low-voltage distribution-specific applications

4.5 Service via microwave systems The provision of telecommunication services to an electric supply location via radio and microwave systems is outside the scope of this standard.

4.6 Responsibilities All wireless installations are expected to comply with, at a minimum, applicable requirements from the National Electrical Code® (NEC®) (NFPA 70) and National Electrical Safety Code® (NESC®) (Accredited Standards Committee C2) to ensure personnel safety in all aspects of the installation. NOTE—Canadian Electrical Code Parts I, II, and III or other local codes may be applicable in some jurisdictions.

Due to safety concerns, the owner of wireless installations is expected to ensure that the requirements of the NESC and other applicable safety standards are met with respect to access, approach distances, and qualified personnel around energized facilities. Also, the owner of the tower and/or pole is expected to ultimately accept responsibility for the overall coordination of work to be done on or at the site of the tower and/or pole. At electric supply locations (power stations and power line transmission and distribution structures such as towers or poles), the owner shall provide the expected GPR and the electrical characteristics for determining touch and step potential information. All work off the ground on the power line towers or poles, including placing and routine maintenance operations, shall be performed by qualified or licensed personnel.

5. Hybrid fiber-optic isolation systems A hybrid optical fiber system (see Figure 1 and Figure 2) is typically composed of three segments: a wireline (e.g., copper, steel, aluminum) to fiber cable junction (CFJ); a length of optical fiber cable or jumper; and an optical electrical interface (OEI). The CFJ and OEI provide circuit arrangements on each side of the optical fiber cable that convert electrical signals to optical signals for transmission through the optical fiber(s) and then reconvert those signals back to standard electrical telecommunication signals. The optical fiber cable(s) or optical transmission links between the CFJ and OEI may vary in length, depending on the locations of the CFJ, the OEI, and the physical layout of the telecommunication facilities serving the site. The user should be aware that some digital services and/or equipment, such as high-bit-rate digital subscriber line (HDSL), may affect service performance objective (SPO) Class A 12 service due to synchronization issues that may preclude the circuit from operating before, during, and after the fault. The wire-line portion of the circuit needs to be properly conditioned if SPO Class A is to be provided.

SPO Class is defined in IEEE Std 487.

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

Figure 1 —Typical hybrid fiber-optic isolation system for electric power stations

Figure 2 —Typical hybrid fiber-optic isolation system for wireless cell sites

5.1 Topologies for hybrid optical fiber isolation systems There are four basic topologies for a hybrid fiber-optic isolation system. In each topology, configuration requirements for the OEI portion of the installation are the same. The configuration requirements for the CFJ are different in each topology and vary depending on CFJ equipment grounding design criteria. The requirements associated with any listing of the equipment by a Nationally Recognized Testing Laboratory shall be met in order to preserve the listing. The four topologies are described below: a)

Topology 1: The CFJ is located outside the zone of influence (ZOI) (location 3 in Figure 6), and the OEI is located inside the electric supply location (location 1 in Figure 6). This arrangement is recommended for all CFJ equipment. See Figure 3. Note that circuit functionality may be improved when circuit equipment designed for improved performance with local grounding is installed in this configuration and properly grounded (see 8.4).

Figure 3 —Typical set up for topology 1

Topology 2: The CFJ and OEI are both located inside the electric supply location ground grid (location 1 in Figure 6). This installation includes placing the CFJ at the edge of the grid, at or near the fence bonded to the ground grid, or placing both ends in adjacent mountings inside the electric supply location. This topology is similar to the arrangement described in IEEE Std 487.1 where the metallic cable from the CO traverses the ZOI and terminates at or inside the ground grid. 8

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

See Figure 4. The unique technology of hybrid fiber systems allows the CFJ to be located with greater separation from the station ground than the discrete or modular components included in IEEE Std 487.1. This technology facilitates configurations with increased separation between remote and station ground references to reduce touch potential hazards. See 8.5 for specific recommendations. In this configuration, the electronics located in the CFJ are exposed to foreign potentials on the dedicated cable pairs and shield, which may result in damage or failure if the CFJ equipment (except for lightning arrestors) is not designed for isolation from local grounds. Further, if the CFJ installation is not under exclusive control 13 of a communications or power utility, the NEC applies; and with the additional required equipment, this installation will not be isolated from local grounds and may be unable to perform the intended function. This topology is not recommended if local grounding is required for CFJ electronics or cable pair protection. The dedicated cable pairs are to be in a nonmetallic enclosure, such as polyvinyl chloride (PVC) conduit, to prevent accidental or unprotected contact. The use of personal protective equipment (PPE), such as rubber gloves and a rubber safety mat on which to stand, is mandatory (see OSHA 29CFR1910 [B38]). NOTE—When the CFJ is at the edge of the grid and just outside the fence, the grid is to be extended around the CFJ as described in IEEE Std 487.

Figure 4 —Typical set up for topology 2

Topology 3: The CFJ is located inside the ZOI (location 2 in Figure 6), but outside the ground grid of the electric supply location; and the OEI is located inside the electric supply location (location 1 in Figure 6). See Figure 5. In this configuration, the electronics located in the CFJ are exposed to foreign potentials on the dedicated cable pairs and shield, which may result in damage or failure if the CFJ equipment (except for lightning arrestors) is not designed for isolation from local grounds. Further, if the CFJ installation is not under exclusive control 14 of a communications or power utility, the NEC applies; and with the additional required equipment, this installation will not be isolated from local grounds and may be unable to perform the intended function. This topology is not recommended if local grounding is required for CFJ electronics or cable pair protection.  

13 14

For design criteria when local grounding is required for electronics or cable pair protection at the CFJ location, see installation configuration 1 and/or configuration 2 in 8.4. For design criteria when isolated equipment (no electronics or pair grounding) is used at the CFJ location, see 8.5.

Exclusive control is defined in NEC Articles 90.2(B)(4) and (5). Exclusive control is defined in NEC Articles 90.2(B)(4) and (5).

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

Figure 5 —Typical set up for topology 3

Topology 4: This topology is without a metallic dedicated cable (as defined in IEEE Std 487). The CFJ and facility interface point (FIP) (see Figure 7) are collocated inside a multigrounded neutral (MGN) network (see Figure 8) at a pre-existing terminal location where the 300 V point and the extent of the ZOI cannot be practically determined. The available services may be restricted to SPO Class C only.

NOTE—The CFJ may be located inside the ZOI only when topologies 1 and 2 are not feasible and then only when the safety considerations and the applicable procedures listed in 8.4 and 8.4.3 have been met.

Figure 6 —Locations at or near electric supply locations

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

Figure 7 —Typical location of a FIP

Note 1—See items e) and f) in 8.4.4. Note 2—May be restricted to SPO Class C. See IEEE Std 487.

Figure 8 —Simplified protection configuration for topology 4

6. Telecommunications service to electric supply locations When electric power stations receive telecommunications services via metallic wire-line facilities (metallic twisted-pair cables), IEEE Std 487 and IEEE Std 487.1 are used to determine the level of electrical protection needed at the electric power station and the protection scheme to be used. IEEE Std 487.1 also covers the protection measures for wire-line facilities traversing the station at large electric power stations. Technology, however, has been moving from metallic wire-line facilities to optical fiber cable. When the telecommunication facilities serving the electric power stations are composed of optical fiber cables for the entire facility, the user shall refer to IEEE Std 487.2. When the telecommunication facilities serving the electric power stations use metallic wire-line components in part of the telecommunication circuit and optical fiber systems in the remainder of the telecommunication circuit, this standard, IEEE Std 487.3, shall be used. 11

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

Wireless sites built inside or attached to the grounded fences of electric power stations (see location 1 in Figure 6) can be protected using either the standards recommended in IEEE Std 487.1 for metallic wire-line facilities or the recommendations in this standard for optical fiber facilities. Wireless sites that are located in close proximity to an electric supply location (see location 2 in Figure 6) subject to GPR may require special protection. BTS equipment manufacturers usually require an earth reference of less than 5 Ω to ensure good grounding to dissipate lightning strikes. Even if that value can be reached, any direct connection to the MGN distribution network will transfer the local GPR to the environment. In rural areas, this connection can create touch voltage problems some kilometers away from the HVE point. This earth reference offers a path for fault current during a fault-produced GPR event. When the fault-produced GPR event causes the earth to rise relative to remote earth, the transfer of potential will cause the current to flow through the low-impedance ground grid of the wireless sites and drain through the remote grounded metallic paths such as the telephone cable and power neutral. In some situations, special HVP on any wire-line or metallic telecommunication cable interface may be required.

6.1 Voltage protection levels The 300 V point is the maximum voltage used to define the ZOI limit. The calculation method of the ZOI boundary based on a fixed voltage reference is explained in 9.8 of IEEE Std 367-2012. When determining the peak value of voltage in meeting this criterion, adding an appropriate value of dc offset of the transient voltage to the steady-state GPR (expressed in volt peak asymmetric) is necessary. NOTE—Many administrations have chosen a value of 300 V, either root-mean-square (rms) or peak, as the GPR upper voltage limit. Other administrations have chosen values such as 420, 430, or 650 V rms or peak. Some administrations have chosen even higher voltages on the basis of their higher cable and equipment dielectric withstand capabilities.

Voltage protection levels in this standard are given in terms of peak values because some degree of a dc offset may be superimposed on the sinusoidal wave form. As a result of the nonsymmetrical wave shape, the relationship between the volt rms and volt peak values is not usually considered to be as shown in Equation (1).

V peak = Vrms

( 2)

(1)

Users may specify values in terms of rms, but if they wish to choose their own offset factor for the first half cycle of the wave shape, the following asymmetric relationship may be used:

V peak Asymmetric = Vrms

( 2 )1 + e ( 

−π X / R)

  

(2)

where X/R

is the power system reactance over resistance value

Example: What is the maximum stress voltage, under worse-case fault conditions, given that the GPR V rms = 2000 V when the power system X/R ratio = 12?

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

Using Equation (1),

Vpeak Asymmetric

−π   (12 ) = 2000 2 1 + e  ≅ 2828.4 [1.77] ≅ 5006 Volts  

( )

6.2 Locations at or near high-voltage towers or poles High-voltage isolation systems, such as those used at electric power stations, may be used to effectively protect the metallic telecommunications plant at many high-voltage tower and pole sites. However, because the GPR at a high-voltage tower or pole can be significantly higher than at an electric power station, the isolation capability of the high-voltage isolation equipment and/or the isolation capability of the metallic telecommunications plant may be exceeded (see ATIS 0600316 [B3]). Prior to implementing a high-voltage isolation system at a high-voltage tower or pole site, the maximum, expected, site faultproduced GPR shall be determined. An analysis of GPR calculations is presented in IEEE Std 367. Information concerning the application of high-voltage isolation systems for metallic facilities is contained in IEEE Std 487.1. The telecommunications outside plant serving equipment at or near power line high-voltage towers or poles (see location 3 in Figure 6) is subject to GPR. Although the probability of a severe fault-produced GPR occurrence at a particular power line tower or pole is lower than that for a similar occurrence at an electric power station, the fault-produced GPR magnitude can be significantly greater because of higher grounding resistance. Grounding at high-voltage towers and poles is usually accomplished through the use of ground rods, counterpoise conductors, and overhead grounding conductors (OGCs). This arrangement typically results in a greater resistance to earth than is achieved through the use of the large-area grounding grids or mats employed at electric power stations. Unless special protection measures are employed, a fault on the transmission and distribution systems may introduce currents into the wire-line (metallic-based) telecommunications plant resulting in service outages and possible plant damage. In some locations, mainly locations with extensive buried metallic infrastructure, this effect is reduced through the common bonding and grounding requirements of national standards.

6.3 Electrical protection considerations for telecommunications outside plant serving high-voltage tower and pole sites The telecommunications outside plant serving high-voltage tower and pole sites requires special electrical protection considerations because of the large currents and fault-produced GPR that can occur at these locations during lightning and power fault events. A phenomena known as power arc follow-through is the worst-case scenario for a lightning-initiated power fault to a transmission line. Under power arc followthrough conditions, a lightning strike could initiate a single-, double-, or triple-phase power fault to a tower or static wire grounding system. These combined fault voltages and currents should be taken into consideration when determining reliability and service continuity for radio sites attached to transmission line structures. Dielectric optical fiber cable or direct microwave systems provide a high level of dielectric strength (see ITU-T K.57 [B37]) during these adverse conditions. The fault current and GPR can damage not only the telecommunications outside plant serving the location, but also the equipment being served. Equipment damage can occur when the wire-line telecommunications outside plant presents an electrical connection to remote earth, permitting the full fault-produced GPR to appear across the equipment between its local ground connection and its telecommunications ports connecting to the wire-line telecommunications network. The mitigation of outside plant and equipment damage from high-voltage transmission line faults should be a primary objective, and electrical protection measures should be implemented.

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

6.4 Electrical protection measures 6.4.1 All-dielectric optical fiber cable Effective electrical protection of the telecommunications outside plant may be accomplished by using an all-dielectric optical fiber cable to serve electric supply locations. Serving the telecommunications equipment at an electric supply location site using an all-dielectric optical fiber cable, from an electrical protection perspective, provides the simplest and most reliable solution to a complex problem. Service can be provided using an optical fiber cable from the CO to the site (see IEEE Std 487.2), or alternatively, by using a shorter optical fiber cable from the CFJ to the site (see Clause 5 and Clause 8). 6.4.2 Optical fiber cable with metallic members When the use of optical fiber cables with metallic members cannot be avoided, such as when using an OPGW, then a transition point should be established. The transition point is usually accomplished by splicing within a closure. At this point, the metallic members are stopped and should be grounded (or protected from overvoltages), and the all-dielectric optical fiber cable starts. For aerial installations, such as OPGW or cables with metallic members, the distance between the transition splice and the equipment connected to the optical fiber should allow a minimum of 3 m (10 ft) of all-dielectric optical fiber cable. NOTE—The use of metallic conduit, for the all-dielectric optical fiber cable, between the transition point and the equipment is not recommended.

6.5 Typical grounding 6.5.1 Electric power stations The design of grounding electrode systems for electric power stations is a complex subject, beyond the scope of this standard. See IEEE Std 80 for information. 6.5.2 Typical grounding at power line structures such as towers or poles Traditional lattice towers consist of four-legged structures with spacing between the legs ranging from 3 by 4.5 m (10 by 15 ft) to 12 by 12 m (40 by 40 ft). Their grid impedance is recommended by the NESC to be less than 25 Ω (measured in accordance with IEEE Std 81™-1983 [B25]). In conductive soils with high water table, 0.5 Ω is possible without augmenting the grounding systems. In poor soils, such as crystalline granite or basalt, the grid impedance may exceed 200 Ω. Many towers have ground rods driven at all four corners and ground rings or counterpoise grounds to lower their earth resistance. When wireless sites are located underneath a tower, their ground grid may augment the existing tower grounding and reduce the impedance of the ground grid. When the ground grid of the wireless site is built to the side of the tower and bonded to the tower, the impedance of the ground grid will be reduced and may approach the characteristics of a ground grid for a small substation. When additional wireless providers co-locate and change the parameters of the ground grid, a review of the electrical characteristics will be required to ensure a safe and reliable ground grid design. Single metallic monopoles typically have less than 1 m2 (10 ft2) earth contact and rely on the concrete and steel foundation for an earth reference. These sites will rarely obtain 25 Ω or less. When the ground grid for 14

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

the site is built to the side of the monopole, the contact area of earth electrodes is significantly increased, thereby lowering the ground grid impedance. Wooden “H” fixtures and single monopole leads sometimes have no earth reference in low lightning areas. Because they are ungrounded or source-grounded systems, they rely on their vertical clearance and the resistance of the wooden structure to insulate or isolate from ground. A fault on these structures can be violent and have extended clearing times. When wireless sites are attached to these structures, they introduce a grounded system into an ungrounded environment. This arrangement may cause severe damage to the grounded system and all remote grounded conductors during fault conditions. Wooden poles with multigrounded (Y) distribution under builds provide multiple discharge paths for fault current and will reduce the earth current through the ground grid that causes GPR. The NESC requires these systems to be bonded to the MGN vertical on the joint-use structures and to maintain vertical and horizontal clearances to assure safe conditions while personnel are working on the pole. If the grounded coaxial or other conductors extend up through or above the ungrounded phase conductors, they should meet NESC Rule 239. A fault of the ungrounded system may distribute fault currents over the neutral distributions network and other grounded conductors and thereby reduce the earth return current through the wireless site’s ground grid. Significant damage to the equipment and other structures in the immediate vicinity may occur until the current drops below dangerous levels. This risk is particularly a problem in rural areas with few ground references or rocky and high-resistant soils. Throughout areas subject to lightning, many power companies employ overhead grounding systems: OPGW (IEEE Std 1138-1994 [B29]), overhead ground wire (OGW), OGC, sky wires, or static wires. These overhead grounding systems provide protection to the transmission systems by providing a shield above the phase wires that directs the lightning to ground. The overhead grounding systems may be tied together from tower to tower to provide multiple discharge paths. The impedance of the overhead grounding system will reduce the current at each subsequent tower until the lightning is discharged. During a line-to-ground fault or follow-through fault, the line current will be distributed along multiple discharge or power follow current paths; this overhead grounding system will reduce ground return current at individual towers and reduce clearing time of the fault by providing a more direct path to operate relays. These systems follow many different protection designs, from being grounded at each tower and the substations to being insulated with a 3–5 kV spark gap device at every tower or every fourth tower. The spark gaps may be stopped two to four spans before the substation or extend from the substation three to four spans only to protect the substation alone. In low lightning areas, they may not exist at all, and each tower is left to stand on its own. The net effect of the overhead grounding system is to reduce the ground return current at individual towers by providing multiple discharge paths. This arrangement, in turn, reduces the current flowing through the ground grid, reduces clearing time, and lowers fault-produced GPR to manageable levels. 6.5.3 Typical grounding requirements for BTS Several documents, such as R56B [B41], are in general use in the wireless industry. These documents provide minimum grounding requirements, along with site preparation recommendations, necessary to meet personnel safety and warranty conditions from the equipment vendors or manufacturers. These documents tend to recommend low ground impedances for 50 to 60 Hz power, as well as at lightning frequencies, at the sites. When the wireless sites are located at or near power line transmission and distribution structures such as towers or poles, enhancements of the ground field may be necessary to meet these requirements to reduce step, touch, and mesh voltages. As a reminder, and for this standard, mesh voltage is the maximum touch voltage to be found within a mesh of a ground grid; step voltage is the difference in surface potential experienced by a person bridging a distance of 1 m (3 ft) with his or her feet without contacting any other grounded object; and touch voltage is the potential difference between the GPR and the surface potential at the point where a person is standing, while at the same time having his or her hands in contact with a grounded object. See IEEE Std 80 for additional information on these terms. 15

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

7. Telecommunications service to electric supply locations— recommendations The use of all-dielectric optical fiber cables is the preferred solution since it solves some of the problems of providing protection at electric supply locations. Special protection considerations pertaining to optical fiber systems serving electric supply locations are primarily a function of the presence or absence of metallic members in the optical fiber cable, conduits, or locating systems. The use of all-dielectric optical fiber cable provides immunity from the effects of faultproduced GPR and induction at the electric supply location. The use of optical fiber cables containing metallic strength members, a metallic foil vapor barrier, metallic conduit, locate members, or talk pairs is not recommended within the ZOI because it raises protection considerations relating to GPR and induction.

7.1 GPR-related protection considerations When an optical fiber cable is employed between the electric supply location and the edge of the ZOI, the metallic elements of the cable shall be isolated from the electric supply location ground and grounds within the ZOI. This isolation is necessary to prevent the fault-produced GPR from being introduced directly onto the metallic components. An intentional low-impedance ground connection to the metallic components will allow potentially damaging currents to flow on the cable from the grounded point to remote earth at times of power faults. When the optical fiber cable traverses the GPR ZOI, it should have sufficient dielectric strength in its outer jacket to preclude any breakdown between earth (or a grounded support strand in aerial construction) and its inner metallic components.

7.2 Induction-related protection considerations When the metallic members are isolated from ground, induced voltages will be developed on the metallic members and will appear between the metallic members and ground. If all metallic elements in the cable are isolated, all will have the same voltage induced on them, and there will be no stress between metallic members in the cable. There will be stress between the metallic components and ground. Therefore, the dielectric strength of the cable’s outer insulating jacket needs to be sufficient to withstand the expected fault-produced longitudinal induction. Where both electric supply location fault-produced GPR and induction in the ZOI are present, the vector sum of the two voltages will be at a maximum at the electric supply location and will appear between the ground grid and cable. The most critical need for isolation, therefore, is at the electric supply location proper and in the nearby ZOI.

7.3 Benefits of all-dielectric cables The use of all-dielectric optical fiber cables is recommended to serve these electric supply locations when isolation is required (as in the case of a BTS under high-voltage lines). Installing appropriate support hardware to maintain the cables’ all-dielectric properties is critical. Placing the last section from at least 30 m (100 ft) outside the fall line of the phase wires on transmission towers and placing all parallel runs within the transmission corridor underground in PVC conduit are recommended. If metallic support strands are used or the optical fiber cable is lashed to existing cables, care should be taken to avoid grounding the strand or anchors within 15 to 20 m (50 to 60 ft) of the electric supply location ground grid to reduce the risk of touch voltage problems. The use of a strand insulator (see NESC Rule 279) with adequate voltage rating is encouraged.

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

8. Design recommendations for CFJ installations Since the CFJ contains electronic equipment, its location should be accessible to authorized maintenance personnel and provide a reasonably safe environment for working. Safety concerns at the CFJ may include touch potential from an adjacent metallic conduit, guy wires, monopoles, and metallic fencing as well as step potential from surrounding soil. While the probability that a person will have contact with the earth and a cable pair or shield at the exact time of a fault-produced GPR event is low, technical personnel are cautioned to avoid working at or near the CFJ during thunderstorms when the probability of a power fault or lightning strike is increased. For optical fiber cable or metallic facilities between the CFJ and CO (see Figure 1 and Figure 2), normal grounding practices should be applied. The metallic facilities between the CO and CFJ should be protected in accordance with the requirements for the appropriate service types and SPO described in IEEE Std 487.1. At the CFJ, the all-dielectric optical fiber cable interconnecting the OEI is terminated in an opticalelectrical signal conversion terminal that, in turn, is connected to metallic facilities. In most instances, those metallic facilities are owned and maintained by the telecommunications service provider. Regardless of the design and make-up of the facilities, locating equipment designed for local grounding, such as carrier terminals, optical-electrical conversion terminals, and repeaters or regenerators outside the GPR ZOI, is important. As with other protected apparatus, there is the risk of protector operations and service interruptions due to GPR during power fault conditions. Induced voltages into a wire-line cable from any paralleling power line fault current may also cause protector operations and, consequently, service interruptions. The CFJs may be located, in accordance with the topologies of 5.1, at a remote drainage location (RDL) or at the edge of the ZOI based on fault-produced GPR calculations in accordance with IEEE Std 367, or located within the ZOI (on- or off-grid) when all components are designed and installed for safe operation without local grounding. See 8.4 and 8.5 for associated installation recommendations.

8.1 CFJ at electric power stations There are several instances wherein the CFJ may be located at an electric power station. The following applications are typical:   

Utility or generation company use of all-dielectric fiber to facilitate intra-substation telecommunications (e.g., telecommunications connectivity among multiple control buildings on a common substation ground grid). Use of utility, transmission, or distribution company-owned optical fiber (e.g., OPGW, ADSS, wrapped fiber 15) to facilitate inter-substation telecommunications (where substations are 1 to 80 km distant). Use of utility-owned all-dielectric fiber to extend telecommunications circuits from a telecommunications service provider’s demarcation point inside a generating plant to an adjacent switchyard control building.

In these telecommunications applications, the following attributes of the CFJ are typical:   15

CFJ is bonded to the substation ground grid or generating plant ground grid. CFJ is locally powered (e.g., via floating 125 V dc, floating 48 V dc, 120 V ac).

Wrapped fiber is described in IEEE Std 1594™ [B34].

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

 

CFJ is typically located proximate to the telecommunications service provider’s existing demarcation point. CFJ metallic inputs are connected to the station side of any co-located isolation equipment.

8.2 CFJ located outside the ZOI of an electric supply location A CFJ is preferentially located outside the ZOI of an electric supply location based on GPR calculations performed in accordance with IEEE Std 367. The GPR experienced at a properly designed CFJ location outside the ZOI is expected to be 300 V peak asymmetric or less. The following telecommunications applications are typical:   

Telecommunications service to an electric supply location where the calculated GPR equals or exceeds 20 kV peak asymmetric or where the ZOIs of multiple adjacent electric supply locations overlap. Telecommunications service to a wireless site co-located with utility transmission or distribution towers or monopoles). Customer-owned CFJ located in proximity to the telecommunications service provider’s demarcation point on an industrial campus, with all-dielectric optical fiber used to extend telecommunications facilities to one or more electric power stations.

In these applications, the following attributes of the CFJ are typical:    

CFJ is locally grounded. CFJ is either line powered (contingent on telecommunications service provider’s tariffs and support) or locally powered (e.g., 120 V ac not referenced inside the ZOI, 48 V dc photovoltaic system with battery backup). CFJ is often located outdoors. CFJ metallic inputs are typically connected to telecommunications service provider’s dedicated metallic cable at the RDL.

For the specific case of a CFJ located in proximity [more than 3 m (10 ft)] to transmission or distribution lines, a ground ring with a minimum of 2 AWG solid bare tinned copper wire 0.4 m (16 in) deep should be placed in the soil encircling the CFJ and bonded to the CFJ ground in order to reduce touch and step potential. The ground ring is designed to reduce the touch potential near a high-voltage power line right of way. Working on an insulated blanket at such a location also reduces the effects of touch and step potentials. NOTE—In some locations, mainly locations with extensive buried metallic infrastructure, this effect is reduced through the common bonding and grounding requirements of national standards.

8.3 CFJ located within the ZOI of an electric supply location A CFJ may be located within the ZOI of an electric supply location based on GPR calculations in accordance with IEEE Std 367. However, the expected GPR at the location of the CFJ within the ZOI shall be coordinated with the dielectric strength of the dedicated telecommunications service provider’s cable serving the CFJ and the PPE so that their respective dielectric strengths are not exceeded.

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

The following telecommunications applications are typical:   

Telecommunication service to an electric supply location where the calculated GPR equals or exceeds 20 kV peak asymmetric or where the ZOIs of multiple adjacent electric supply locations overlap. Telecommunication service to a wireless site co-located with utility transmission towers or monopoles. Customer-owned CFJ located in proximity to the telecommunications service provider’s demarcation point on an industrial campus, with all-dielectric optical fiber used to extend telecommunications facilities to one or more electric power stations.

In these applications, the following attributes of the CFJ are typical:     

CFJ and associated equipment must NOT be locally grounded. CFJ is either line powered (contingent on telecommunications service provider’s tariffs and support) or locally powered (e.g., 120 V ac not referenced inside the ZOI, 48 V dc photovoltaic system with battery backup). CFJ is typically outdoors. CFJ enclosure or pedestal must be nonmetallic. One or more dielectric pads are installed in proximity to the CFJ enclosure to afford added step potential and touch potential protection for personnel working on the CFJ equipment.

8.4 Conditional deployment of CFJ with electronics or pair protection that requires grounding by design The following defined installation configurations, within topology 3, (see 5.1), apply when considering the location and placement of a CFJ in which local grounding is required by design for electronics or pair protection. Gas tube protection should be placed from conductors to shield (except for SPO Class A) to protect the electronic equipment from induced voltage and fault-produced GPR in these configurations. For CFJ installations where neither equipment nor telecommunications pair-protection require local grounding, see 8.5. 8.4.1 Installation configuration 1: voltage level II protection (SPO Classes B and C) If the installation location being considered for the CFJ is classified as voltage level II and the CFJ installation includes equipment or electronics that are not isolated from ground (i.e., requires grounding), the requirements of IEEE Std 487 and IEEE Std 487.1 apply when remote grounding is acceptable. NOTE—Voltage levels are defined in IEEE Std 487.

Specifically for SPO Classes B and C, if remote grounding is not acceptable and local grounding is required, then the CFJ shall be deployed using the following requirements, provided the basic impulse insulation level (BIL) of the protection equipment is rated 1000 V or higher: a)

The installation should be treated as a SPO Class B or Class C protection location.

Utilize the protection methods in Table 1 and Figure 8 of IEEE Std 487.1 to determine the appropriate equipment to be deployed on the wire-line cable pairs at the CFJ location. Ground the required protection equipment on the metallic cable to a made local ground.

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At the edge of the calculated ZOI, establish an RDL. As backup protection, an appropriate SPO Class B compatible protective device is recommended to help protect the CO side of the network from any damaging currents resulting from a GPR event.

Refer to IEEE Std 487 for the SPO rating of the circuits and IEEE Std 487.1 for exact circuit levels and protection schemes to be utilized.

SPO Class B service may not allow personnel to reliably place emergency calls, such as 911, since SPO Class B phone circuits may drop emergency calls and require re-dialing.

Note that this location is designated as a high-voltage location. This location is subject to all the protection and safety issues that would apply at any voltage level II high-voltage location. If properly located, Level II is limited to 1000 V, and OSHA Class-1 rubber gloves and rubber safety mats rated for 10,000 V minimum are to be used when working at this location. Refer to OSHA 29CFR1910 [B38] for information on voltage ratings. 16

NOTE—This protection design may result in a poor or reduced reliability circuit design scheme.

8.4.2 Installation configuration 2: voltage level III protection The installation of a CFJ, or associated equipment, requiring local grounding by design, is not recommended in a voltage level III location. 8.4.3 Protection configuration for topology 4: MGN network As indicated in IEEE Std 487 and illustrated in Annex G of IEEE Std 367-2012, the ZOI concept is not applicable inside an MGN network. The applicable grounding requirements of local or state codes (i.e., NEC, NESC, Canadian Electrical Code Parts I, II or III, etc.) shall be applied at the CFJ location. Neutral voltage and contact voltage calculations can be made using IEEE Std 367 and IEEE Std 80 to help ensure safe step and touch voltage values. NOTE—This configuration may be restricted to SPO Class C.

8.4.4 Constraints at the CFJ/FIP location The following constraints apply at the CFJ/FIP location: a)

All CFJ/FIP metallic access is already referenced to local ground and bonded to the MGN.

Pairs to shield voltage stress should be limited by overvoltage shunting protectors for SPO Class B and C services.

Local ground is bonded to the shield of the general use cable.

NOTE—This configuration may be restricted to SPO Class C. Do not use the MGN from the serving site.

In addition to the recommendations in IEEE Std 487, apply contact voltage (step and touch) mitigation at the CFJ/FIP location using one of the following methods:

In Canada, refer to CSA Z259.4 for gloves [B9] and CSA Z259.6 for blankets [B10]. Other jurisdictions may have equivalent standards.

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1) 2) 3)

Place and arrange a permanently mounted dielectric pad (or pads) adjacent to the CFJ to accommodate and encourage personnel to stand on the pad while working on the metallic facilities within the CFJ. Place an insulating rubber safety mat with a minimum withstand rating greater than the difference of potentials apparent at the location where the personnel would stand. Use an arrangement of equipotential conductors and gravel (or cement), as defined in IEEE Std 80, designed to reduce contact voltage to a safe value. This equipotential plane is to be connected to the MGN.

NOTE—This configuration may be restricted to SPO Class C.

The CFJ should be placed sufficiently distant from the power station fence, including any other metallic surface connected to the high-voltage ground grid, so that personnel working in the area would not be exposed to hazardous transfer touch and step potentials.

Do not place the CFJs and FIPs at or near (within one-span length) a pole line located at a transition point between underground and aerial power cable. A high variation in inductive coupling factor between underground power cable neutral (shield) and aerial neutral may produce higher GPR at this transition point during a ground fault in the distribution network.

The dielectric withstand rating of the dedicated cable between the CFJ and FIP should be coordinated with the expected GPR in the area it traverses. See IEEE Std 487.

A nonmetallic cabinet or pedestal is recommended to house the CFJ and/or FIP.

Figure 8 shows the recommended configuration to ensure the required reliability in function of the SPO class of service and voltage level. NOTE—This protection design may result in a poor or reduced reliability circuit design scheme. Also, service may be restricted to SPO Class C.

8.5 Conditional deployment of CFJ with electronics or pair protection that does not require grounding by design This subclause addresses protection configurations using a hybrid fiber-optic isolation system with a CFJ that requires no locally grounded electronics or pair protection, located inside of the ZOI (either on or off the grid), and OEI located within the electric supply location ground grid. In this scenario, certain considerations should be included in the design to incorporate isolation methodologies similar to those applied to the isolation equipment addressed in IEEE Std 487. The issues associated with this scenario are based on the presence of GPR in the soil and structures adjacent to the CFJ and the possible GPR transferred from the power neutral system on the metallic cable at the CFJ location. The safety considerations included in IEEE Std 487 should be applied to CFJ installations that could be within the ZOI, where high-voltage potentials can appear in the surrounding soil and conductive materials. Additionally, the following conditions should be considered: a)

A nonmetallic dielectric cabinet or pedestal and possibly a nonmetallic fence are recommended to house the CFJ when the CFJ is located within the ZOI.

The dedicated cable extends from the FIP to the CFJ.

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

The dielectric withstand rating of the dedicated cable between the CFJ and FIP should be coordinated with the expected GPR in the area it traverses. See IEEE Std 487.1.

In high lightning areas, a lightning arrestor rated to limit the clamping voltage below the dielectric withstand rating of the dedicated cable should be considered for facility protection. When used, the lightning arrestor should be enclosed in a dielectric housing and connected between the dedicated cable shield and an acceptable earth ground near the CFJ.

Since the CFJ is located within the ZOI, the shield of the dedicated cable is not grounded at the CFJ.

Do not use any electronic equipment or protection (other than possibly a lightning arrestor) at the CFJ that requires local grounds. The cable shields are not to be used for grounding purposes.

When working on the metallic facilities within the CFJ, personnel should avoid simultaneous contact with the metallic facilities, or connected equipment, and the surrounding earth or conductive structures. This touch-potential isolation can be accomplished by a combination of the following methods: 1) 2) 3)

Place and arrange a permanently mounted dielectric pad (or pads) adjacent to the CFJ to accommodate and encourage personnel to stand on the pad while working on the metallic facilities within the CFJ. Place and work atop an insulating work blanket with a minimum dielectric isolation rating greater than the expected maximum GPR at the work location. Use the rubber gloves and insulating blankets that are mandatory when working on or near protective equipment or telecommunication cables serving the electric supply location. Refer to OSHA 29CFR1910 [B38] for information on voltage ratings. 17

Any local powering structure or conductors for the CFJ should be contained in dielectric housings or conduits. Any exposed conductive materials connected to the CFJ, such as power solar panels, should be located at least 3 m (10 ft) above grade on a nonmetallic support structure. Use of commercial ac power at this location should take into account the transfer of GPR voltages through the service neutral where isolation transformers may be required.

The CFJ should be placed sufficiently distant from the power station fence (including any other metallic surface connected to the high-voltage ground grid), or additional dielectric barriers should be added so that personnel working at the CFJ would not be exposed to hazardous transfer, touch, and/or step potentials.

A sign warning technicians of the hazards shall be prominently displayed and affixed on the outside the enclosure or housing. A typical sign might read as follows: WARNING High-voltage (15 kV or more) potential difference may be present between the surrounding soil and conductive materials at this location. Rubber gloves and insulation mats are required. Do not change the grounding scheme. Refer questions to the protection engineer.

In Canada, refer to CSA Z259.4 for gloves [B9] and CSA Z259.6 for blankets [B10]. Other jurisdictions may have equivalent standards.

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9. Powering arrangements at electric supply locations Electric supply locations have a variety of powering arrangements. Electric power locations typically have local power systems, either ac or dc, for the equipment located within the site. For reliability purposes, the local commercial power is usually backed up with either batteries or engine generators, or both. Power sources at or near power line towers or poles need special considerations (see Figure 9).

NOTE 1—Isolation distance between primary and secondary grounding electrode systems, minimum 15 m (30 m preferred). NOTE 2—This distance should not exceed 9 m. NOTE 3—The isolation transformer uses oil-paper insulation, with high-voltage insulation isolating and insulating the primary winding with neutral from the tank and secondary winding. Internal shielding between the windings is bonded to the tank. NOTE 4—At the isolation transformer, the tank may be ungrounded for additional isolation (NEC Article 250-110, Exception #2), but is connected to surge arresters on the load side [secondary surge arrester, i.e., metal oxide varistor (MOV), three-pole, 175 V]. If the transformer is not grounded or if metallic conduit is used, Note 1 shall be followed. If the transformer is not grounded, then it may be grounded during work operations for added personnel safety. NOTE 5—Secondary surge arrester (MOV), two-pole, 175 V. NOTE 6—Secondary surge arrester (MOV), two-pole, 175 V. NOTE 7—High-voltage station-class surge arrester. Coordinate BIL protective levels needed for the isolation transformer with overvoltage capability required for isolation. NOTE 8—Ground fault indicator(s) may be required at utility service disconnecting means. NOTE 9—A main disconnect may be required by the NEC. NOTE 10— The isolation transformer shall have a label indicating whether it is ungrounded. The pole shall have a CAUTION note requiring a hot stick for measurements.

Figure 9 —Typical electrical schematic for installation of isolation transformers at wireless sites

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9.1 Typical ac power service to wireless locations at power line towers or poles The commercial power to a wireless site is often a single-phase 120/240 V secondary service with the center-tapped neutral bonded to the primary MGN at the distribution transformer and grounded at the wireless site. This secondary neutral provides a path for the transfer of high potential during line-to-ground faults at a tower. Studies (van Waes et al. [B46] and [B47]) have shown that when OGWs (static or lightning wires) are employed, the distribution low-voltage conductors may carry one-third of the current back to the source transformer. Without OGCs, they are the primary discharge path.

9.2 Distribution transformers The enclosures housing the electronic equipment require ac power that is typically provided through a distribution transformer. If a flashover occurs on the high-voltage system, the resulting fault current will travel to the distribution neutral conductor. The local HVE GPR will then be transferred to the MGN network. If the local GPR is of sufficient magnitude and the neutrals are not properly isolated, a safety hazard due to touch voltage and serious damages could occur in the neighborhood. Rural areas will be more critical as GPR can be transferred through many kilometers by the MGN network (see Rajotte et al. [B43] and [B44]). Distribution transformers located in close proximity to high-voltage transmission towers and used to provide ac power to an electronic equipment enclosure (also located in close proximity to high-voltage transmission towers) shall have the neutrals separated by a spark gap or similar device. Alternatively, a separate and dedicated distribution transformer shall be used to provide power solely to the electronic equipment enclosure. This transformer (associated with the tower and the electronic equipment enclosure) shall not be used to provide ac power to either residential or commercial structures nearby, but they could be used to provide power to several enclosures of different wireless service providers, provided that they are bonded together (see van Waes et al. [B46], [B47], and [B48]). Providing an isolation transformer in series with the commercial power is recommended to mitigate the hazard (see Figure 9). The Y grounded distribution system is stepped down from the primary voltage to 120/240 V ac and then transmitted in an ungrounded configuration to a 120/240 V grounded isolation transformer, in accordance with Figure 9, with a BIL of 50 kV (or greater) that meets or exceeds the test standards IEEE Std C57.12.00â&#x201E;˘ [B23] and IEEE Std C57.12.90â&#x201E;˘ [B24] or equivalent international standards. This design allows the wireless equipment to have a neutral grounded electrical system that will provide a return path to the low-voltage isolation transformer. This design also provides safe operation on the ground grid and isolation for the high-voltage return current associated with a line-to-ground fault of the transmission voltage. If the isolation transformer is on the high side, then see Rajotte et al. [B44].

9.3 Electrostatic coupling Ungrounded metallic telecommunications cables and hardware, as well as personnel, located in the vicinity of high-voltage power transmission lines may become electrically energized by electrostatic coupling to the high-voltage power line. An ungrounded conductive object, including a person, will assume a potential relative to the earth, based on the power line voltage and geometry, and the capacitance of the object or person with respect to both the power line and the earth (see ATIS 0600316 [B3]). Personnel working near high-voltage lines may become charged by the electric field surrounding the lines. The voltages can be large, and the available current is usually small, below the level that may cause electrical injury.

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

WARNING The electric shock or arc obtained may be startling, causing accidental injury as a result of involuntary reaction. Grounding of the telecommunications plant and hardware helps to minimize the possibility for injury because of involuntary reactions by keeping the cables and hardware and the earth near them at the same potential.

9.4 Engine generating units All permanent engine generators shall be installed in accordance with the requirements of the NEC, or equivalent local code, for a separately derived system. NOTE—There may be some sites, such as hill tops or remote areas, that do not have commercial service available; therefore, they are equipped with permanent engine generators.

Engine generators when used on a temporary basis (less than 45 days) to provide ac power while waiting for permanent utility ac power or until service is restored after a service outage shall comply with the following restrictions:  

The engine generator and any separate above-ground metallic fuel storage container shall be effectively bonded to the site’s grounding system. Buried grounding rings or temporary grounding mats shall be installed around the engine generator and any metallic fuel storage container.

Whenever practical, refuel equipment off the power line easement or fee-owned property to eliminate arcing. When such refueling is not practical, transfer flammable liquids between metal containers only after electrically bonding the containers together to eliminate the potential of fuel ignition due to arcing.

10. Typical dc powering arrangements at OEI and CFJ The powering of optical fiber telecommunications facilities requires two separate sources as shown in Figure 10 (for a grounded CFJ) and in Figure 11 (for an isolated CFJ meeting the requirements of 8.3). An optical fiber HVP system relies on fiber to pass the telecommunications signal and is only as reliable as the electrical systems providing the power to their active components. The CFJ, OEI, and network channel terminating equipment (NCTE) at the end user should be powered from the most reliable dc uninterruptible power source (UPS) systems available. NCTE is a general term that can be applied to equipment that terminates special circuits at a customer’s premises.

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Figure 10 —Typical dc powering arrangements at the OEI and a grounded CFJ— circuit dc power loop extended to fiber system at CFJ

NOTE—Use PPE at this location.

Figure 11 —Typical dc powering arrangements at the OEI and an isolated CFJ (see 8.3)— circuit dc power loop extended to fiber system at CFJ

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10.1 Wire-line–fiber cable junction (CFJ) The CFJ at the end of the metallic pairs is typically powered by a remote ground referenced, locally derived or isolated source such as a CO line power, a locally powered ac-to-dc UPS system, power-over-fiber (PoF) powering, or solar power. If the CFJ is in the CO or at a loop electronics extension such as a fiber hut, the assumption is that the CFJ is located outside the ZOI of the electric supply location. If the CFJ is within the ZOI, the CFJ may be subject to service interruption due to power induction or GPR during a fault. The CFJ shall not be directly powered from an electric supply location’s ac power unless an isolation transformer is used. A backup source, such as a battery system, should be used to ensure power reliability. The dc powering arrangement of the CFJ will vary from site to site based on circuit types, availability of adequate current or voltage from the CO, location of the CFJ, distance from the OEI, reliability goals, and installation costs. Typical dc powering arrangements include the following: a)

CO or loop electronics extension (dc power loop provided with standard circuit configurations). This arrangement includes a variety of options such as standard 23 mA, 60 mA, and sealing current (see Figure 10 for a grounded CFJ and Figure 11 for an isolated CFJ) and depends on the type of service used. Several circuit designs such as analog data (i.e., SCADA) and 56 kB digital data do not have a line power dc component, and another powering arrangement should be considered.

b) Express powering loops derived from separate pairs from the CO or loop electronics extension specifically designed for HVP applications (see Figure 12 for a grounded CFJ and Figure 13 for an isolated CFJ). Confirmation of availability from the service provider is recommended. NOTE—Dial-tone circuits (i.e., plain old telephone service) should not be used as a power source because they are not reliable.

PoF systems that convert high-power laser light from the OEI into dc power at the CFJ over fiber cable (see Figure 14 for a grounded CFJ and Figure 15 for an isolated CFJ).

d) Locally powered ac-to-dc UPS system with local batteries within the CFJ (see Figure 16 for a grounded CFJ and Figure 17 for an isolated CFJ). e)

Locally powered solar cell system with local batteries within the CFJ (see Figure 10 for a grounded CFJ and Figure 11 for an isolated CFJ).

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Figure 12 —Typical dc powering arrangements at the OEI and a grounded CFJ— express loop power option for CFJ fiber system

NOTE—Use PPE at this location.

Figure 13 —Typical dc powering arrangements at the OEI and an isolated CFJ (see 8.3)— express loop power option for CFJ fiber system

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Figure 14 —Typical dc powering arrangements at the OEI and a grounded CFJ— PoF power option for CFJ fiber system

NOTE—Use PPE at this location.

Figure 15 —Typical dc powering arrangements at the OEI and an isolated CFJ (see 8.3)— PoF power option for CFJ fiber system

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Figure 16 —Typical dc powering arrangements at the OEI and a grounded CFJ— local power options for CFJ fiber system

NOTE—Use PPE at this location.

Figure 17 — Typical dc powering arrangements at the OEI and an isolated CFJ (see 8.3)— local power options for CFJ fiber system

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10.2 Remote end and OEI The OEI where signal conversion occurs (electrical to optical and vice versa) should be powered from a reliable local source. The remote end should have a local power source such as a station battery. Using the same backup power for the OEI, NCTE, BTS, and the end user’s telecommunications, and any other associated, electronic equipment to avoid separate power systems failing at different times is recommended. This setup will also eliminate maintaining duplicate facilities. This setup requires that voltage, current, and polarity requirements be coordinated and/or be converted through the appropriate dc-to-dc converter to power the remote end circuits. The user should note that the BTS equipment often requires positive 24 V dc, but other voltages may be used.

11. Construction concerns and general recommendations The following are concerns and general recommendations pertaining to the construction of the CFJ, OEI, and the optical fiber cable(s) connecting the CFJ and OEI: a)

The optical fiber cable(s) shall be all-dielectric, i.e., the cable(s) do not contain metallic members, including copper pairs.

b) There should not be any metallic wires placed along or near the optical fiber cable(s) (e.g., locating or tracing wires). See Annex B for information related to locating buried all-dielectric optical fiber cable. c)

The optical fiber cable serving the OEI at the electric supply location shall be in dielectric conduit (PVC Schedule 40 minimum). The conduit shall extend, as a minimum, to a point 3 m (10 ft) outside the fence.

d) If more than three 90° conduit bends are required, one or more hand-holes (or above-grade pull-box) shall be provided along the conduit run to facilitate optical fiber installation and reduce required cable-pulling tension. e)

At any one site, all enclosures housing the wireless electronic equipment shall be on the same grounding grid.

When the CFJ and OEI sites are fenced, the fences shall be grounded as required by NESC Rule 092E or as required by an equivalent local code.

g) Sites should be set up with crushed stone, gravel, or asphalt to minimize the hazards from step and touch potential. See IEEE Std 80 for guidance. Underground cables should not cross transmission line grounding systems and should maintain a minimum clearance of 6 m (20 ft) from the perimeter of an existing grounding system to prevent disturbing the site’s ground field.

11.1 Existing facilities For aerial cable installations, not on joint-use poles, metallic messengers shall be grounded at the edge of the ZOI and should be isolated throughout from the CFJ to the electric supply location.

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11.2 Locating buried all-dielectric optical fiber cable Annex B provides information about the methods and techniques available for locating buried all-dielectric optical fiber cables.

12. Installation and inspection considerations 12.1 Installation considerations The equipment enclosures located at high-voltage transmission poles and towers (e.g., the BTS or other telecommunications enclosures) should be connected to the site grounding system. A bare copper ground ring, minimum of 2 AWG solid bare tinned copper conductor, should be buried around the equipment mounting pad to reduce hazardous touch and step potentials. The equipment mounting pad should be located at least 2.5 m (8.2 ft) from the fence unless that section of the fence is bonded to the siteâ&#x20AC;&#x2122;s ground grid. Safe limits for potential differences during fault conditions, including step and touch potentials, are described in IEEE Std 80. These methods should be applied to telecommunications installations at electric supply locations.

12.2 Inspection considerations Periodic, usually annual, detailed inspections by all companies (e.g., power utility, telephone, and wireless) of all aspects of protection facilities in and around the high-voltage site are necessary to ensure that special protection requirements have not been violated or negated. As a protection system is quiescent, many such defects will not become apparent until the protection system fails to function properly under fault conditions and causes failure or damage, or both, to critical equipment and, possibly, injury or loss of life. All companies should work out the frequency within which such inspection should be conducted. In addition to planned, periodic tests, this standard recommends that a thorough inspection of the protection facilities, including bonding and grounding, be made following each case of faulty or questionable operation of such facilities, particularly if damage has resulted.

13. Safety 13.1 General safety considerations The basic safety objective (see Poulin [B40]) is to protect personnel from coming into contact with both remote and local grounds simultaneously. Therefore, safety consideration should be directed toward the following goals: a)

Educating personnel regarding the special hazards of working on telecommunication facilities located at electric supply locations.

b) Minimizing the possibility of simultaneous contact with both remote and local grounds. 32

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

Reducing the length of time that personnel spend working at the site under conditions that may expose them to danger.

13.2 Electrical safety Technicians assigned to work in telecommunication sites at or near electric supply locations and/or at the CFJ should be made aware of proper safety techniques. Work shall not be performed on telecommunication circuits when electrical storms are occurring in the area through which the circuits pass. Safety precautions are required for ALL work with conductive facilities, such as metallic telephone conductors, metallic cable shields and armors, metallic messengers, remotely grounded metallic structures, and the like. Observe the following safety precautions:    

Always contact the site’s owner representative before performing any work inside a site at an electric supply location. Use a rubber blanket (and/or insulated footwear) and rubber gloves of at least 20 kV dielectric strength rating (Class 2). Refer to OSHA 29CFR1910 [B38] for information on voltage ratings. 18 Isolate parts of the body from contacting the earth, grounded conductors, or any extensions of earth (local ground). Avoid touching or stepping between the remote grounded facilities and local ground or locally grounded facilities such as earth, walls, and fences.

Different administrations may implement stricter safety precautions, detailed in applicable safety practices, for installing or maintaining protective devices or placing cables within the GPR ZOI.

13.3 Radio frequency (RF) safety awareness All individuals that might work in RF transmission sites shall have received training on RF awareness as required by Federal Communications Commission (FCC) regulations (see Bulletin 65 [B13]). In 1996, the FCC adopted regulations setting forth RF exposure limits for cell sites. 19 These guidelines apply to operations in the frequency range of 300 kHz to 100 GHz. The maximum permissible exposure (MPE) for personnel varies depending on frequency. The MPE levels are conservative and have been set to provide substantial safety factors for persons working near cellular transmitters. The FCC regulations are “exposure” standards and not limits on “emissions” of RF energy. As such, compliance is designed for both workers and the general public to avoid RF exposure that exceeds the FCC guidelines. NESC Rule 420Q addresses high-frequency radiation effects on workers in both the supply and telecommunications spaces arising from communication antennas mounted in those spaces. Clearance and separation requirements are included in NESC Rule 235I. 18

In Canada, refer to CSA Z259.4 for gloves [B9] and CSA Z259.6 for blankets [B10]. Other jurisdictions may have equivalent standards. 19 See Report and Order, ET Docket 93-62, FCC 96-326. See also First Memorandum Opinion and Order, ET Docket 93-62, FCC 96487, and Second Memorandum Opinion and Order and Notice of Proposed Rulemaking, ET Docket 93-62, FCC 97-303. http://www.fcc.gov/oet/dockets/et93-62/.

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

Refer to IEEE Std 1654™ [B35] for information about safety programs to ensure compliance with the applicable regulations for the RF protection of workers from wireless antennas located near or on electrical power line structures. 13.3.1 General guidelines The following are general guidelines (see Corley [B8]) for use by all personnel (including utility line workers) working on or near antennas:     

Look for caution signs, pertaining to RF, prior to starting work. Assume all transmitters are energized. Maintain a distance of 2 m (6 ft) from active transmitters. At a distance of 2 m, RF exposure will not exceed the MPE. Obey all posted signs and warnings. Minimize time spent in posted areas.

Do not violate the specified approach distance posted on the signs unless a personal RF monitor is worn.

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

Annex A (informative) Bibliography Bibliographical references are resources that provide additional or helpful material but do not need to be understood or used to implement this standard. Reference to these resources is made for informational use only. [B1] Ashdown, B., N. Korbel, and T. Scott, “Interface specifications for protection and grounding in wireless base stations,” INTELEC 97, 19th International Telecommunications Energy Conference, pp. 359–367, Oct. 1997. [B2] AT&T Engineering Design Information for Power Industry Communications Services, 1971. [B3] ATIS 0600316-2008, Electrical Protection of Telecommunications Outside Plant. [B4] Bellarmine, G. T., and M. Lee, “Techniques of effective cellular site facility protection,” Proceedings of the IEEE Southeast Conference, pp. 387–390, Apr. 2002. [B5] Blume, S. W., High Voltage Protection for Telecommunications. IEEE Press, 2011. [B6] Chowdhuri, P., “Parameters of Lightning Strokes and Their Effects on Power Systems,” Proceedings of the IEEE/PES Transmission and Distribution Conference and Exposition, vol. 2, pp. 1047–1051, 2001. [B7] CIGRÉ SC36 WG 04, “Guide on EMC in Power Plants and Substations,” Technical Brochure #124, 1997. 20 [B8] Corley, B., Electro Magnetic Energy Evaluation and Management for Antenna Sites. Motorola, 2001. 21 [B9] CSA Z259.4-M 1979, Rubber Insulating Gloves and Mitts. [B10] CSA Z259.6 1981, Rubber Insulating Blankets. [B11] Del Alamo, J. L., “A powerful tool for grounding design in high voltage substations,” 6th Mediterranean Electrotechnical Conference, vol. 2, pp. 1440–1444, May 1991. [B12] Electrical Transmission and Distribution Reference Book. Westinghouse Electric Corporation, 1964. [B13] FCC OET Bulletin 65, “Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields,” Edition 97-01. 22 [B14] Grcev, L., and V. Filiposki, “Zone of influence of ground potential rise on wire-line communication installations in urban areas,” International Symposium on Electromagnetic Compatibility, pp. 580–585, Aug. 1997. [B15] Grcev, L., V. Filiposki, and V. Arnautovski, “Ground potential rise influence near HV substations in urban areas,” 16th International Conference and Exhibition on Electricity Distribution (CIRED 2001), vol. 2, June 2001. [B16] Grcev, L., A. P. J. van Deursen, and J. B. M. van Waes, “Frequency domain analysis of the lightning current distribution to ground at the transmission line tower with cellular phone base station,” IEEE International Symposium on Electromagnetic Compatibility, Istanbul, Turkey, vol. 1, pp. 637–640, May 2003. 20

CIGRÉ publications can be obtained from the International Council on Large Electric Systems (http://www.cigre.org/gb/publications/brochures.asp). 21 Available at http://www.osha-slc.gov/SLTC/radiofrequencyradiation/corley_motorola_eme_report.pdf. 22 This OET bulletin can be obtained from the Office of Engineering and Technology of the Federal Communications Commission (FCC), http://www.fcc.gov/ Bureaus/Engineering_ Technology/Documents/bulletins/oet65/oet65.pdf.

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

[B17] Grcev, L., A. P. J. van Deursen, and J. B. M. van Waes, “Lightning current distribution to ground at high voltage tower with radio base station,” IEEE Transactions on Electromagnetic Compatibility, vol. 47, no. 1, pp. 160–170, Feb. 2005. [B18] Grcev, L., A. P. J. van Deursen, and J. B. M. van Waes, “Time domain analysis of the lightning current distribution at the HV tower with GSM system,” 2003 IEEE PowerTech Conference, June 2003. [B19] IEEE Std C37.90™-2005, IEEE Standard for Relays and Relay Systems Associated with Electric Power Apparatus. 23, 24 [B20] IEEE Std C37.90.1™-2002, IEEE Standard for Surge Withstand Capabilities (SWC) Tests For Relays And Relay Systems Associated With Electric Power Apparatus. [B21] IEEE Std C37.90.2™-2004, IEEE Standard for Withstand Capability of Relay Systems to Radiated Electromagnetic Interference from Transceivers. [B22] IEEE Std C37.90.3™-2001 (R2006), IEEE Standard Electrostatic Discharge Tests for Protective Relays. [B23] IEEE Std C57.12.00™, IEEE Standard for Standard General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers. [B24] IEEE Std C57.12.90™, IEEE Standard Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers. [B25] IEEE Std 81™-1983, IEEE Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a Ground System. [B26] IEEE Std 81.2™-1991, IEEE Guide to Measurement of Impedance and Safety Characteristics of Large, Extended or Interconnected Grounding Systems. [B27] IEEE Std 525™, IEEE Guide for the Design and Installation of Cable Systems in Substations. [B28] IEEE Std 789™, IEEE Standard Performance Requirements for Communications and Control Cables for Applications in High-Voltage Environments. [B29] IEEE Std 1138™-1994 (Reaff 2002), IEEE Standard Construction of Composite Fiber Optic Overhead Ground Wire (OPGW) for Use on Electric Utility Power Lines. [B30] IEEE Std 1222™-2004, IEEE Standard for All-Dielectric Self-supporting Fiber Optic Cable. [B31] IEEE Std 1243™-1997 (R2008), IEEE Guide for Improving the Lightning Performance of Transmission Lines. [B32] IEEE Std 1428™-2004, IEEE Guide for Installation Methods for Fiber-Optic Cables in Electric Power Generating Stations and in Industrial Facilities. [B33] IEEE Std 1594™, IEEE Standard for Helically-Applied Fiber Optic Cable Systems (Wrap cable) for Use on Overhead Utility Lines. [B34] IEEE Std 1613™-2003, IEEE Standard Environmental and Testing Requirements for Communications Networking Devices in Electric Power Substations. [B35] IEEE Std 1654™, IEEE Guide for RF Protection of Personnel Working in the Vicinity of Wireless Communications Antennas Attached to Electric Power Line Structures. [B36] IEEE Std 1692™-2011, IEEE Guide for the Protection of Communication Installations from Lightning Effects. [B37] ITU-T K.57, Protection measures for radio base stations sited on power line towers. 25

IEEE publications are available from The Institute of Electrical and Electronics Engineers (http://standards.ieee.org/). The IEEE standards or products referred to in this clause are trademarks of The Institute of Electrical and Electronics Engineers, Inc. 25 ITU-T publications are available from the International Telecommunications Union (http://www.itu.int/). 24

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

[B38] OSHA 29CFR1910, Occupational Safety Standard—Subpart 1: Personal Protective Equipment. [B39] Pham, K. D., “Design a safe grounding system for rural electric power distribution substations,” Rural Electric Power Conference, pp. C1/1–C1/4, 1990. [B40] Poulin, J., “Safety aspects related to the installation of mobile telephone antennas on HV towers,” 2000 IEEE ESMO, pp. 163–164, Oct. 2000. [B41] R56B Standards and Guidelines for Communications Sites. Motorola Communications Enterprise, 2005. [B42] Rajotte, Y., R. Bergeron, A. Chalifoux, and Y. Gervais, “Touch voltage on underground distribution systems during fault conditions,” IEEE Transactions on Power Delivery, vol. 5, pp. 1026–1033, Apr. 1990. [B43] Rajotte, Y., J. De Sève, J. Fortin, R. Lehoux, and G. Simard, “Earth potential rise influence near HV substations in rural areas.” CIRED 18th International Conference on Electricity Distribution, Turin, June 2005. [B44] Rajotte, Y., J. Fortin, and G. Lessard, “Safety issues related to the connection of MV and HV grounding systems outside substations,” Electricity Distribution, vol. 2, 2001. [B45] Sunde, E. D., Earth Conduction Effects in Transmission Systems. New York: Dover Publications, 1968. [B46] van Waes, J. B. M., A. P. J. van Deursen, M. J. M. van Riet, and F. Provoost, “Safety aspects of GSM systems on high-voltage towers: an experimental analysis,” IEEE Transactions on Power Delivery, vol. 17, pp. 550–554, Apr. 2002. [B47] van Waes, J. B. M., A. P. J. van Deursen, M. J. M. van Riet, F. Provoost, and J. F. G. Cobben, “A systematic approach to improving grounding circuits,” Transmission and Distribution World, vol. 54, no. 6, pp. 74–77, June 2002. [B48] van Waes, J. B. M., M. J. M. van Riet, A. P. J. van Deursen, and F. Provoost, “Safety aspects of GSM systems on high voltage towers,” Proceedings of the 9th IEEE International Conference on Transmission and Distribution Construction, Operation and Live-Line Maintenance, pp. 165–168, 2000.

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

Annex B (informative) Locating buried cables

B.1 Overview Telecommunications companies need detection systems to accurately map and locate their underground facilities. The impact of an outage of optical fiber cable has become more severe as the network grows in size because the telecommunications industry is more dependent on fiber to the x (FTTx) services. Currently, no detection systems can, with a high certainty of accuracy, detect or locate optical fiber cables placed, or installed, underground that do not also include some type of additional parallel wire tracers or electronic markers. However, the cost of the locating equipment continues to decrease, and the accuracy tends to improve over time. The present procedures for locating facilities is sometimes described as an art, indicating that the accuracy of the locate depends on the operator’s knowledge and competency with the equipment as well as the locator’s familiarity of the existing plant. The locator’s abilities and knowledge are often the most important factors in an accurate locate. Currently, accurate records of subsurface facilities are often not always available. Locating and rerecording all existing facilities would be very expensive and, therefore, opportunities offered during the installation of new facilities should be used to locate existing adjacent facilities to generate new records and/or update maps.

B.2 Locating methods Various methods are in use today to aid in the detection of subsurface utilities, including the following three most common methods:   

Magnetometry Electromagnetic induction (EMI) Ground penetrating radar

These methods utilize similar electromagnetic principles, but each has its own benefits and drawbacks. B.2.1 Magnetometry Magnetometry detects permanently magnetized materials. The magnetrometry method is simple to use and requires little training. However, it is limited to detecting ferrous materials because only significant gradients can be measured. Magnetometry devices are also prone to interference from above-ground structures with accuracy of detection subject to the depth, size, and object composition. B.2.2 Electromagnetic induction (EMI) EMI methods are able to detect all metals and, theoretically, aid in determining the location of subsurface nonmetallic objects. By artificially inducing a secondary magnetic field in buried facilities, through induction or direct contact, EMI instruments can locate these fields and thus determine their location based on peak or null readings. Also, through the conductivity characteristics of soil, although slight, EMI 38

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

instruments are sometimes able to locate non-conductive objects. This location is obtained simply by the lack of response detected from an EMI instrument of a non-conductive object. The downside of EMI technology is that it is unable to produce accurate depth readings and is susceptible to interference from above-ground structures. If multiple metallic objects from various utilities are in proximity to one another, deviating from the utility of interest, by the operator, is quite possible. B.2.3 Ground penetrating radar Unlike EMI technology, ground penetrating radar instruments utilize waves, not fields. Ground penetrating radar instruments send short-wave lengths (microwaves) into the ground to detect objects. This technology is based on the reflection of waves (much like a bat using sound waves to navigate through caves). With many data collection points, a radargram can be formed that creates a three-dimensional representation of objects below the ground. The attractiveness of ground penetrating radar technology is its ability to detect multiple materials and its immunity to above-ground interference. Unfortunately, since ground penetrating radar is based on waves, wave attenuation causes it to be severely limited by depth. Also, the data obtained is difficult to interpret and requires a high skill level by the technician.

B.3 Benefits Additional benefits from accurate mapping of underground facilities includes more efficient troubleshooting analysis, more rapid location of buried splices, and more accurate records that will help improve network analysis and planned upgrades of a telecommunications outside plant.

B.4 Recommendations General recommendations include the following items:    

The current policies of including tracer wires, electronic (EMI) markers, and/or warning tapes should be followed in all buried placements, particularly when all-dielectric facilities (fiber cables) are being deployed. Standard practice should include placement of electronic marking system at buried splice locations for all-dielectric systems (optical fiber–FTTx systems) to help in locating access points along a route for maintenance and repair activities. If telecommunications company practices require the placement of tracer wire or marker with alldielectric facilities, the use of ground penetrating radar devices does not appear to be cost effective or appropriate. During installation, the Differential Global Positioning System (DGPS) should be used to accurately indicate the location of the new facilities. This information should be documented into an electronic database and mapping system that eventually contains all facilities. Whenever a utility facility (e.g., cables, splice case) is located, the positioning of the located facility should be added to the central mapping system.

The mapping databases and the precision of the Global Positioning System (GPS) used to make and document the locations of the plant facilities will determine the usefulness and return on investment. A civilian-grade GPS receiver can monitor the signals emitted by the satellites and determine its position in latitude, longitude, and altitude with an accuracy ranging from 10 m to down to < 1 cm, depending on the quality of the receiver. The detail and ease of access of the computer system where the information is stored is critical to its success and long-term usefulness. Establishing a common set of parameters and the same data formats by the different utilities (e.g., telecommunications, power, sewer, water, natural gas) to record and exchange location data is useful.

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

One of the main purposes of locating utility facilities is to avoid damage to buried plant and equipment. An integral part of that purpose is attained during the routine activities of construction and installation:   

Pre-survey checklist One-call (811) marking of facilities in the surrounding area Following best practices and methods and procedures during buried deployments

Guidance on such design and engineering practices can be found in many industry documents and standards including the following:   

Telcordia SR-1421, Blue Book – Manual of Construction Procedures, Issue 5, July 2011. ANSI-EIA-TIA 590, Standard for Physical Location and Protection of Below Ground Fiber Optical Cable Plant, 1997 by Telecommunications Industries Association. Common Ground, Study of One-Call Systems and Damage Prevention Best Practices, August 1999 (http://www.commongroundalliance.com).

B.5 Provisions for locating buried all-dielectric optical fiber cable The task of locating buried all-dielectric optical fiber is particularly challenging and important due to the absence of traceable metallic components. Thus, it is imperative that marking devices be planned prior to construction and deployed during the construction process to ensure accurate traceability of these critical buried telecommunications facilities. B.5.1 Permanent markings To achieve general protection and awareness of buried telecommunications facilities, the use of permanent, above-ground markers is a viable alternative. These passive warning devices indicate that underground facilities are in the general area and should display the following information:   

The name of the facility owner The telephone contact number to call to obtain the exact location of the facility The characteristic orange telecommunications marker color

Permanent markers are typically placed within sight of one another, but no further than 300 m (1000 ft) apart. These telecommunications markers are available in several forms (e.g., rigid PVC dome post, flexible composite slat, flush pavement markers). Marker posts have a white base with orange topper and are usually installed to extend 1.3 to 1.8 m (4 to 6 ft) above finished grade for maximum visibility. B.5.2 Electronic markers Depending on their assigned resonant frequency and color, electronic markers are utilized to mark a wide range of buried facilities. Two types of markers may be used for telecommunications and cable television (CATV) applications: 

The first type of electronic marker is the solid orange-colored marker that is used for general telecommunications applications. These markers are generally available in five common forms for varying applications:  Near-surface marker  Ball marker  Mid-range marker

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities



 Full-range marker  Disk marker The second type is the orange/black-colored marker that is used specifically for CATV applications. These markers are generally available in several forms, each optimized for specific applications:  Near-surface marker  Ball marker  Disk marker

The electronic marker typically consists of a sealed shell containing a passive antenna: a low-frequency resonance circuit tuned to a specific frequency corresponding to the facility type to be located. The compatible locator sends a signal to the marker and thereby energizes it. The signal is then reflected back to the locator. Electronic markers are best installed during construction, when the facility route is visible to the eye (for plowed-in or trenched-in placement) or temporarily locatable (for directional boring). B.5.2.1 Recommendations for electronic marker placement To ensure subsequent traceability of buried all-dielectric optical fiber cable, electronic marker placement recommendations include the following locations and crossings:              

Handholes Buried splices Repair points Slack loops Depth changes Laterals Bends (changes of direction, arcs) Conduit ends of horizontally directional bored facilities Water crossings Major road crossings Rail crossings Pipeline crossings Utility crossings (e.g., natural gas, buried electric distribution and transmission, sanitary and storm sewer) Adjacent utility poles or pedestals

Refer to specific manufacturer recommendations for electronic marker application, installation spacing, and depths. B.5.2.2 Availability of RF identity microchips in electronic markers It is noteworthy that certain manufacturers offer ball markers, mid-range markers, full-range markers, and disk markers that contain an RF identity microchip. This feature allows for introduction and storage of facility data. Each marker comes pre-programmed with a unique identification number and is, therefore, able to confirm its specific identify upon successful location. These more sophisticated electronic markers are useful for   

Marking buried facilities in congested urban areas with a high density of underground networks Marking buried facilities in rural areas where few physical landmarks can be referenced Custom marking high-value facilities

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities

B.5.2.3 Near-surface electronic markers Near-surface markers are typically recommended for urban applications. Near-surface markers allow for convenient marking of telecommunications facilities located beneath concrete or asphalt. The marker is installed vertically at a shallow depth in a hole drilled in soil, street, or sidewalk pavement. Near-surface markers have become popular due to their relative ease of installation. Their maximum installation/detection depth is typically 0.6 to 1 m (2 to 3 ft); they are commonly installed shallower, based on application. Refer to specific manufacturer specifications and placement recommendations for complete application details. B.5.2.4 Optical fiber marker locator tape In situations where the all-dielectric optical fiber cable is placed via trenching (e.g., open trench) or plowing, optical fiber marker locator tape is a viable location technology. The discrete markers in the marker locator tape are locatable at a nominal depth of 0.6 m (2 ft) below finished grade, via a telecommunications marker locator. This locator transmits a unique RF signal for telecommunications facilities to the marker tape to facilitate location of the buried optical fiber cable. Features of available telecommunications locator tape include the following:     

Non-continuous, locatable markers (for use within the ZOI) Frequency coded specifically for telecommunications Orange colored (standard telecommunications color) Provides a visual indication (i.e., orange marker tape) of optical fiber cable buried below to reduce probability of future dig-ins Compatible locator provides both audible and visual indications to operator

Typically, manufacturers recommend that marker locator tape be placed no more than 0.5 m (18 in) below finished grade and directly above the optical fiber cable to be marked. Placement of the locator tape within 15 cm (6 in) of a metallic object (e.g., adjacent metallic cable, buried pipe) should be avoided. The use of continuous locator tape should be avoided when used within the ZOI for marking buried optical fiber. B.5.3 Application of DGPS During facility installation, DGPS technology may be utilized to mark and document the locations of new plant facilities. This information must be documented in a secure electronic database and mapping system that contains the utility’s expansive facilities. The quality of surveying equipment, mapping databases, and the utilization of DGPS will determine the usefulness and accuracy of the latitude, longitude, and altitude data collected during construction to facilitate subsequent location of the buried telecommunications facilities. B.5.4 Dedicated locating innerduct An alternative method for locating all-dielectric facilities using traditional tone tracing is as follows: 



Place an empty, dedicated, all-dielectric innerduct alongside the dielectric facilities to be located. This innerduct is preferably placed in the same dielectric conduit with the dielectric facilities. As alternatives, a locating innerduct can also placed in a parallel proximity conduit, or a standalone parallel conduit can be placed to accomplish the same function. The maximum length of any section of dielectric innerduct placed for locating shall be 300 m (1000 ft). The endpoints of this dedicated locating innerduct must be clearly and permanently

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IEEE Std 487.3-2014 IEEE Standard for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Through the Use of Hybrid Facilities



 

marked on plant drawings and in the field with surface-accessible closures such as pedestals, cabinets, or handholes. Each section of the dedicated innerduct must be composed of all-dielectric material. The network or CO-side end of this innerduct must be readily accessible for locating purposes, and the subscriber end shall be rigidly closed with a permanent plug or hermetic seal. This dedicated innerduct shall remain empty except during locating procedures. It shall not be used for any permanent facility or permanent conductive component. Both ends of the dedicated locating innerduct should be labeled with a permanently affixed tag to discourage innerduct use for any other purpose. See Figure B.1 for a typical marker tag that may be used to identify the dedicated innerduct. To locate the dielectric facility, the facility locator can insert a temporary locating fishtape or other suitable conductive instrument into the dedicated locating innerduct from the network end to the stop on the subscriber end and then transmit a locating signal using the temporarily inserted instrument. Once the dielectric fiber facility route is identified and marked, the temporary locating instrument must be immediately removed from the locating innerduct. CAUTION

Do not extend conductive materials, such as metallic fishtape, cabling, or drop wire, above or across the ground for distances greater than 1 m (3 ft) when near high-voltage sites such as power stations and towers. Spontaneous GPR from the grounding system, or sustained electric fields from overhead wires, could render the extended conductors an electrocution hazard.

Figure B.1—Typical marker tag for dedicated locating innerduct

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