Surge Protection Devices and Fire Alarms

The first thing we must understand is what a corrigendum actually is, and what is its purpose? BS 0:2021

A standard for standards – Principles of standardization, is the BSI document on how standards are written. This current 2021 revision does not define what a corrigendum is, however, the previous revision from 2016 defines it as:

“3.15 corrigendum alteration and/or addition to a standard that corrects one or more errors or ambiguities inadvertently introduced in either drafting or production and which could lead to incorrect or unsafe application of the standard.”

This means in essence that a corrigendum is used to fix errors that have been introduced during the drafting process. The deletion of point (ii) of regulation 443.4.1 “failure of a safety service, as defined in Part 2” is one of these fixes.

The need to install a Surge Protection Device (SPD) for a fire detection and fire alarm system in a domestic property was never the intention of this regulation and this has been clarified by its deletion by the corrigendum. The fire alarm industry has long acknowledged the existence of lightning and the damage it can do to through surges in the electrical power network. All fire detection and fire alarm equipment, whether domestic or commercial must meet certain product standards to be able to be sold in the UK market. These being:

• EN 54 suite of standards for commercial systems; and

• BS EN 14604 for domestic smoke alarm devices.

Both of these sets of standards reference the Electromagnetic Compatibility (EMC) standards which are a method of complying with the legal requirements of the EU Electromagnetic Compatibility Directive. This piece of EU Law which has been implemented in the UK by The Electromagnetic Compatibility Regulations 2016. This UK law was first introduced in 1992 and has been revised several times over the years until the latest revision in 2016.

Looking at Schedule 1 of this law it provides the General requirements of the statute:

“1. Equipment must be so designed and manufactured, having regard to the state of the art, as to ensure that—

(a) the electromagnetic disturbance generated does not exceed the level above which radio and telecommunications equipment or other equipment cannot operate as intended;

(b) it has a level of immunity to the electromagnetic disturbance to be expected in its intended use which allows it to operate without unacceptable degradation of its intended use.”

With the EMC standards that are already in place, and the Law that manufacturers must comply with, fire detection and fire alarm equipment already has immunity built in to transients that occur from lightning strikes in the vicinity, or by switching in the power distribution system of the low voltage network which includes the switching of large capacitor batteries.

Lightning strikes, while relatively infrequent, are not a recent phenomenon and the introduction of surge protection devices for fire alarm equipment is unnecessary and its introduction into the 2022 amendment of BS 7671 was in error. This erroneous requirement for the fitting of SPDs for domestic smoke alarms has led to some organisations not upgrading their smoke alarms due to the additional costs of installing the SPD. This has now been corrected by the corrigendum.

Will Lloyd FIA Technical Manager.