I thought this was an interesting consideration from NICEIC Q and A on AFDDs. I would have thought the regulation was focused at what might end up connected to a socket rather than the AFDD protection for the circuit. Were that to be the case, then what about all the other circuits that do not have sockets?
It seems reasonable to me.
I have always envisioned that AFDDs protect the occupier from arcing within the fixed wiring, which might have nothing attached.
The product standard for AFDDs states, in the scope:
These devices are intended to mitigate the risk of fire in final circuits of a fixed installation due to the effect of arc fault currents that pose a risk of fire ignition under certain conditions if the arcing persists.
(my highlight).
Regulation 421.1.7 in BS 7671:2018+A2:2022 also relates to a provision for specific final circuits (and talks about the 'circuit to be protected') rather than, for example, Regulations 411.3.3, 708.415.1, 709.531.2, etc, which require RCDs to be provided for socket-outlets (not final circuits supplying socket-outlets).
Were that to be the case, then what about all the other circuits that do not have sockets?
Therefore, this is a really good question.
The definition of a final circuit (and circuit) doesn't necessarily imply that circuits (or the effect of their protective devices) stops at accessories, connection units, or socket-outlets, and plugs and socket-outlets can be used for connection of fixed equipment (or portable or mobile) current-using equipment to circuits.
It is an interesting point - I agree that 'as written' this is exactly what the standards imply - but it does imply a lack of joined up thinking about other things - one is a hidden assumption that only socket circuits suffer from faults that an AFDD may detect, and note even then they only detect something (if at all) once a load is plugged in !
This may be partly correct - circuits that loop through a string of many sockets contain far more joints and therefore potential failure points than a dedicated radial out to a point load like a shower or a cooker which may have no joints at all, except at the load itself and at the CU end.
In the UK of course the lighting circuits are equally complex, but the AFDD designs and rules come mostly from places where lighting and power circuits would normally be combined and there is a assumed 16A load. So in the UK a socket tacked on the 6A lighting circuit in the loft for the TV pre-amp would be AFDD exempt.
Now I'm not a great believer in AFDDs actually working, if your really think the wiring is a fire hazard then there are other things one can do. However, that is beside the point of this discussion, as here we are looking to the regulation for when to use them and that looks a bit wobbly as well.
I think the NICEIC advice is pragmatic and sensible, given the rules as they stand, but the background thinking has a few holes that perhaps ought to be looked into.
M.
Humm, I'm not sure I follow the logic behind the NICEIC's answer - while I agree that current regs aren't retrospective to the existing installation, they surely do apply to the new work - i.e. the new length of cable and the new socket. I can't see how the addition can be said to comply with the latest regs in such cases if an AFDD wasn't provided. It smacks rather like saying you don't need to correct inadequate or defective main bonding when making an indoors addition that relies on ADS ... because the bonding was part of the existing installation.
- Andy.
Yes and no!
Earthing and bonding must be adequate for the addition or alteration: 132:16.
More pragmatically, suppose that a customer obtains two quotes. One says that you must have AFDD, the other does not. Which will you choose?
Wouldn’t it make sense to offer two pricing options—one with AFDDs and one without? That way, the client can decide based on their budget and priorities. While AFDDs aren’t a strict requirement, I always explain that they’re recommended (C3 on a EICR) for improving safety. Give the client the information they need to make an informed decision.
You could also go one step further and give options for PVC/PVC T&E vs LS0H. Caveat time, there are differences between LSF (Low Smoke and Fume) and LSOH (Low Smoke Zero Halogen) cables. Now LS0H is not a requirement for a domestic dwelling BUT it is safer if used. Is this not the realm of a designer and for a small operation the Electrician is the Designer/Installer/Commissioner /Tester
Give the client the information they need to make an informed decision.
And the informed decision will be to go with the cheapest option.
And the informed decision will be to go with the cheapest option.
That's a bit cynical.
I think that I would seek justification for the additional expense - same as for any other tradesman, including a surgeon.
Well a truly informed decision will require the fires and accident figures so lacking from the AFDD sales literature.
Mike.
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