Do we have to fit AFDD's in domestic installations?

[davesparks]

The bit I'm kind of getting at is the criteria for fitting AFDD's.

AFDDs are currently rare and very expensive, the IET know that they won't get fitted by a lot of jobbing electricians doing one-off jobs, rewires, CU changes etc. They also know that for those kind of jobs customers aren't going to accept the cost and will often choose the electrician who ignores the rule if they were to make them mandatory.

The only way the price is going to come down is by AFDDs becoming more commonly used and demand increasing.

By making it a recommendation they know that the people designing/specifying large scale domestic installation jobs, like whole new build estates, will specify AFDDs.
Housing associations, councils, listed buildings people will also start jumping on the band wagon and specify them.

This way the demand will increase and so drive the price down.

In the future we will see them become mandatory everywhere, but not until it is reasonably possible.

Now the cynic in me also wonders if making this a recommendation is also a way of dodging the blame if AFDDs do prove to be as troublesome and unreliable as some think they will be.

 

[mainline]

Adding any electronic circuitry is going to make the installation less reliable in terms of nuisance tripping and failure of the device itself.

Extract from some research into AFDDs:

If it is assumed that some amount of Electrically Initiated Fires (EIF) are initiated by arc-faults, there is still
significant doubt whether the introduction of AFDDs will effectively manage that risk. Empirical and
documentary evidence affirms this, for example, the tripping thresholds stated in the AFDD product standard are higher than the levels at which arc-faults could still cause ignition.

Any benefit brought by AFDDs is not sufficiently evidenced, the incidence rate of AFDD-detectible arc-faults is unknown. The primary disbenefit to AFDD technology is cost, which in a circumstance where AFDDs become mandated, may have the unintended consequence of delaying recommended improvement works.

An additional unintended consequence might be the distraction from more effective prevention of EIF, which principally would involve measures to reduce the general incidence of electrical faults through regular testing and inspection.

 

[AJB Temple]

I live in a timber clad and old oak barn conversion. It has been fully rewired to a high standard. Because of multiple buildings, we have multiple CUs, all Hager. We recently decided to fit AFDDs to all areas where we have any kind of fire risk concern and had no difficulty getting them via our trade accounts. What is interesting is the resistance to using them which I think is largely driven by cost. We paid £102 each, plus fitting and testing and some other necessary changes due to CU space. This is not a trivial sum for AFDD multiples in domestic properties. I am a developer, not a qualified electrician, though I am familiar with the regs. If the regulatory authorities think AFDDs will materially reduce fire risk then having vague wording like "recommended" is ridiculous. Eventually insurance companies will drive this. I specify them in developments now. They make sense to me.

 

[nicebutdim]

Cost is one consideration, but their effectiveness in detecting different types of arc is another valid concern. In the US, the use of these devices has been controversial due to considerable issues with them -what I don't know is whether those issues are down to arc fault detection devices or widespread problems with fixed wiring and these devices functioning as intended.

 

[pc1966]

Others have said most that needs to be said about this, but I guess for non-mandatory situations you need to consider how you might try, however vaguely, to quantify the risk elements that might justify fitting AFDD (or not):

• Is the circuit likely to have equipment of questionable reliability attached? For example, some rental or public sockets would be riskier than a commercial setting with PAT checked stuff, or a newer home with new equipment in use.
• Is the building construction one that is more likely to burn or have a high speed of fire propagation? So old wood buildings or conversions, or places where flammable material might be stored could be factors to apply.
• In the event of a fire, are there unusually big consequences? So a building with folks of limited mobility and/or mental capacity to respond a factor in term of risk-to-life, a historic building or museum might be a factor in terms of loss of irreplaceable material, or high-rise where fire-fighting could be difficult to deploy, etc.

On the flip-side, there might be situations where AFDD are a poor technical fit and are not justified by the above, so places with power tools and similar in use where arcing is likely to trip them.

How you actually weigh up the above is not something I can answer! But if you have no specific reasons to say there is above-average risk, then you could argue that they are offering a negligible advantage and the cost of fitting would be better spent by the customer on linked fire alarms (if not already present) or fire extinguishers, etc.

 

[Vortigern]

I am sorry but the cynic in me observes the fact that the people making AFDD devices sit on the board recommending them. That alone makes me reticent. Then the cost. Most clients will baulk at the cost. On top of that there was a somewhat torrid thread from our partners over the pond re the matter of AFDD suggesting that we do not need them as with our voltage and the use of RCD we already have systems in place that will detect an arc fault and AFDD are superfluous. Essentially, I agree with that contention.
I could take the view that lets throw everything and the kitchec sink at "safety" and cover my derriere. As long as the client can afford it why should I think about these heady matters just comply and charge the customer.
Pragmatically it is not as simple as that. Most clients, domestic wise, will not buy it.
Bottom line; there is currently no neccesity to fit AFDD right now. But....as in the case of RCD, there will be. Whats not to like? We bring in a slight change to the regs, we can charge for a whole new set of OSG, BS7671 and bingo on the product! This will become invevitablly compulsory, at the moment it is not in average domestic wiring. If there is any ambiguity in the definitions that is JPEL's fault not mine.

 

[freddo]

On top of that there was a somewhat torrid thread from our partners over the pond re the matter of AFDD suggesting that we do not need them as with our voltage and the use of RCD we already have systems in place that will detect an arc fault and AFDD are superfluous. Essentially, I agree with that contention.

Another reason is our house wiring doesn't use aluminium cable (except for a tiny number of examples) that is far more likely to suffer arcing than copper wiring.

 

[suffolkspark]

Ive just put a board full of afdds on a thatch re wire as im not on a price so thought even if it gives 1% extra safety im doing it, (im an ex fireman and they burn well ) but the rest of my jobs i wont, they do have Bluetooth though so you can communicate with them with your phone with the hager app

 

[AJB Temple]

An architect friend of mine is just doing a large thatch extension on a job. He's specified AFDDs and I agree it makes a lot of sense with thatch. It's very difficult to get useful data on the cause of electrical fires. Anecdotal evidence seems to suggest that it is rarely faulty wiring in the UK (if done properly by skilled electricians to regs). Faulty appliances such as dodgy washing machines seem to get fingered quite a lot. These things generally are low priced and poor quality and end up in rentals and social housing. Arguably that is where protection is most needed and least likely to occur.

 

[default]

I can't find any really up to date threads on whether we have to fit AFDD's.

I am specifically talking about in a domestic premise. I can see that 421.1.7 shows where an AFDD HAS to be fitted (i.e in one of the 4 bullet points), but then it says below ( the bullet points) it is 'recommended' that AFDD's are fitted in ALL premises for socket outlets.

The Napit Webinar (02/11/2022) kind of skips lightly over this point. At 11 mins and 25 seconds he says something along the lines of 'it is up to the designer whether to use the recommendation of using AFDD's'.

It clearly is not mandatory otherwise the reg would not state the 4 examples of where it actually is mandatory. So it is actually optional, but there isn't any criteria given to help you decide whether or not you should fit one.

Does anyone have any clarification on this?

Your right there are certain situations where they shall be fitted, which seems quite clear. Anything other than this is a recommendation which means it does not need to be done