Are AFDDs mandatory for electrical installations?
The latest edition to the Wiring Regulations BS 7671:2018+A2:2022 mandated the use of Arc Fault Detection Devices (AFDD).
Hager’s Technical Training Manager, Paul Chaffers, discusses the importance of providing additional fire protection following this.
In 2008, the 17th Edition of the Wiring Regulations was released and contained a new section, “532 Devices for the protection against the risk of fire”. That section mentioned devices to provide protection from arc faults, but it was buried away in a “note” containing informative guidance.
Fast forward 10 years to the 18th Edition 2018, where AFDDs became “recommended” due to UK electrical fires still being unacceptably high. It is here that most designers started to really take notice.
Wiring Regulations recommendations
The issue with any recommendations in the Wiring Regulations is knowing when to follow them.
Some say they are only informative and therefore can be ignored. However, BS 7671 lists guidance on the language used within the Wiring Regulations and defines a recommendation as:
“Expression in the content of a document conveying that among several possibilities one is recommended as particularly suitable, without mentioning or excluding others.”
Furthermore, it states that the implication of a recommendation means you should do it.
So, you can see why designers struggle with omitting safety devices when they are recommended.
AFDD with ProTools
Hager’s AFDDs are single modular-sized devices, incorporating circuit-breaker or RCBO and AFDD all in one device. Each AFDD benefits from best-in-class built-in diagnostics which can quickly identify 8 statuses, saving time and effort on site conducting fault finding.
In addition to the on-board diagnostics, the Hager Pilot app contains useful diagnostic guides providing a step-by-step approach to fault finding, ensuring that the professional electrician can quickly and easily identify the cause for any problems encountered.
Hager AFDDs also come equipped with Bluetooth functionality to enable in-situ software upgrades. As technology evolves, new innovative electrical devices will enter the home and may have new and unique electrical signatures that can cause nuisance tripping of the device.
With in-situ software upgrades available via the Hager pilot app, the device firmware can be updated to recognise new electrical signatures eliminating the need to replace the device.
Browse our AFDDs here .
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Where are AFDDs required?
BS 7671:2018+A2:2022 saw the mandating of AFDDs for the first time for a select amount of installation types. Regulation 421.1.7 Requires AFDDs to conform to BS EN 62606 and be used on single-phase socket-outlet circuits up to a current rating of 32A in:
- Higher Risk Residential Buildings (HRRB)
- Houses in Multiple Occupation (HMO)
- Purpose-built student accommodation
- Care homes
For all other premises, AFDDs are recommended for single-phase socket-outlet circuits up to a current rating of 32A.
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What type of work requires AFDDs?
Any work that involves the installation of new socket-outlets in one of the listed installation types will require AFDDs to be provided at the origin of the circuit, including:
- New builds
- Rewires
- Additions and alterations to socket-outlet circuits
- Consumer unit replacements
Where socket-outlets need replacement for maintenance purposes they may be replaced without the addition of an AFDD.
This is permitted for safety reasons and is deemed acceptable, because adding additional cost to maintenance, may prevent it from being carried out. This only concerns a like-for-like swap of damaged accessories and no other alterations. -
How do AFDDs work ?
Traditional protective devices that deal with overcurrent, residual current & overvoltage protection reduce the risk and consequence of electrical fire, but none of these can identify an arc fault. AFDDs use microprocessor technology to analyse the waveform of the electricity being used to detect any unusual signatures which would signify an arc on the circuit.
Numerous parameters are analysed, including the signature, duration and irregularity of the arc, enabling an algorithm to identify arc faults and differentiate these from normally occurring arcs.
This is essential because everyday switching activities produce arcs, for example from switches and contactors as well as arcs from items of equipment with motors, like portable electrical tools, vacuum cleaners and washing machines.
From this, we can see that AFDDs are intelligent devices capable of avoiding unwanted operation. However, from time to time unwanted operation occurs, which can be a problem unless you have the right tools to identify the issue.
