NBC 2016 from BIS Now all IS Become IEC Plz Refer Webpage of BIS for details
10 LATEST UPDATE OF NATIONAL BUILDING CODE FOR EARTHING SYSTEM As per National Building Code 2016, an electrode/pipe/plate (GI is a highly corrosion prone material) and earthing connections leads to excessive corrosion below the soil.
*It is recommended to use a corrosion resistant earthing material like Copper Coated Steel along with Exothermic
welding to have enhanced earthing life & strength to the connection.
National Building Code has been revised and recommended an advanced technology for making an earthing arrangement a more effective and efficient. A Solid low carbon steel rod is a long life earthing material based on the research report of NEGRP conducted by NFPA. Similarly, in-comparison of mechanical joints NBC recommends Exothermic Welding for making an earthing connection more strong and fail-proof. It also provides 100% contact surface area which will decrease contact resistance and improves the life of earthing joints. Likewise, salt & charcoal is also replaced by a ground enhancing material of better quality conforming IEC 62561-7. This earth enhancing compound offers better performance and improves the life of an earthing arrangement irrespective of the soil condition. whereas, salt & charcoal is a major reason of the corrosion in an electrode. Salt is an electrolytic compound which itself corrode any metal in its presence. Hence, NBC recommends an earth enhancing material to be incorporated with an earthing arrangements.
1. PRESENT SCENARIO OF GI PIPE EARTHING
The enclosure shall be earthed in accordance with the relevant BIS and NBC 2016 regulations 7.9 Earthing a. Earthing of all equipment shall be made by using UL listed 3 mtr copper bonded rod (minimum 250 micron) with 17 mm dia, complying with NBC 2016, IS 3043 and IS/IEC 62305-1/2/3&4 standards. The resistance value shall be as low as possible in every case. Lightning b. From the viewpoint of lightning protection, a single integrated structure earthtermination system is preferable and is suitable for all purposes (i.e. lightning protection, power systems and telecommunication systems). The earthing system of a number of
structures shall be interconnected so that a meshed earthing system is obtained. This will give low impedance between buildings and has significant lightning electromagneticpulse (LEMP) protection advantages. Thus, different earthing systems like lightning protection earthing, electrical earthing, safety earthing, electronics earthing etc shall be interconnected. SurgeProtection c. Isolating spark gaps (ISG) shall be complying to IEC 62561-3, used at the places where direct interconnection is non-permissible to create equi-potential bonding throughout the earthing system at the event of lightning with lightning impulse current (10/350 µsec / Iimp) up to 100 KA a d rated i pulse sparko er oltage of ≤ . 5 KV ith IP 67 degree of protection. Surge Protection Devices (SPDs) shall be provided at main’s entry level (LT Panel level / Entry panel – 230/400 V AC or at UPS level) for each external cable (related to power supply, signal, data or any other), connection which is terminated at any item of exposed external equipment, or routed through an outdoor area at Toll Plaza, RO and HQ. The SPD shall be rated in accordance with IEC 61643-11 and NBC 2016 latest and valid standards. k. The SPD shall be non-exhausting metal encapsulated, spark gap based technology. l. The SPD shall be tested as per IEC 61643-11:2011 (or equivalent EN 61643-11:2012) from KEMA or VDE international independent test labs. The SPD shall be rated for 255 V. m. The SPD shall be capable to discharge Lightning current (10/ 350 µs) of 25 kA for L-N and 100 KA for N-E . The device shall ha e oltage prote tio le el of de i e shall e ≤ .5 KV i ludi g inbuilt fuse. n. The SPD shall have current extinguishing capability [L-
N]/[N-PE] : 100 KArms / 100 Arms. The device shall have followed current limitation/Selectivity resulting in no tripping of a 35 A gL/gG fuse up to 50 KArms. 0. The device shall have built in fuse and operation of SPD shall be independent of Line current. No requirement of additional overcurrent protection. o. The device shall have mechanical indication based health indication for L-N and N-PE SPD along with the common potential free contact / changeover contact for remote monitoring. p. Network Surge Protection Device (SPD): The different components of system shall be installed with surge protection device in accordance with IS/IEC 62305-4, the selection/location shall be decided depending upon the criticality of the application. The communication interfaces shall be installed with suitable SPD. General specifications of SPD for POE are mentioned below. Service Provider shall install suitable SPD for 12V DC supply and 5V DC supply, as applicable and complying to IEC 61643-21. 7.8.1 General Specification of SPD for POE: a. The device shall be capable to discharge lightning impulse current (at 10/350µs) of 0.5KA & 10 KA total nominal discharge current (at 8/20µs). b. The device shall be suitable for maximum continuous DC voltage of 48V. c. Voltage Protection level (line to line / line to ground) of de i e shall e ≤ 7 V. d. The de ice shall be enclosed within Zinc die cast material. e. The device shall be DIN rail mounted adopter type with sockets. f. The device shall comply to IEC 61643-21/ EN 61643-21 and shall be UL approved. g. Cut-off frequency shall be minimum 100 MHz.. Plz Contact Mahesh Chandra Manav GM BD JMV LPS LTD M-9910398999/T 0120-4590000 manav@jmv.co.in