AFDDs for single-socket circuits

[Selfmade]

Haven't been on here for a while, so sorry if this has been discussed before.

BS7671 2018 + A2 Regulation 421.1.7 recommends AFDDs for "single-phase AC circuits supplying socket outlets..." (requires in certain premises). My intention is that from September 27th I will recommend them to customers (in practice I already do in some situations) and require a signed waiver if they don't want the expense. At least I will do so for the actual Sockets Circuits - typically ring final, serving a number of sockets for general use and sometimes also fixed equipment via FCUs.

What I'm not sure about is circuits that serve just a single socket, such as a dedicated circuit for a fridge or an oven. In the case of a fridge, it will likely draw less than 2A, so an AFDD is unlikely to perform any useful function. In the case of an oven, one could justify cutting off the plug and connecting it via an FCU, in which case the circuit is no longer supplying a socket, yet with or without a socket it's still the same appliance and the same wiring. Yet in both cases if a socket is fitted an AFDD is recommended according to the regs.

BTW I understand a case could be made for AFDD protection for an oven and oven circuit. But for this question I'm just interested in the definition of 'circuits supplying socket outlets' for the purposes of this recommendation.

 

[pc1966]

Just now a quick search for the Fusebox brand has RCBO for around £15+VAT and AFDD for around £105+VAT, so around £110 extra parts cost per circuit to the customer (inc VAT), and a bit of margin for returns and call outs for odd trips, so say £150.

Not sure what is typical for a home these days, but it is looking like £300-450 extra if you have 2-3 RFC and if not much else (couple of lights, couple of fixed kitchen appliances), then it is probably adding 50% to a CU change?

Some folk won't have issues with the cost but I bet the majority of customers do! More so when it is a hard sell as to what they really offer in terms of improved safety. We see general fire stats quoted from time to time but so far I have not seen an analysis of what AFDD would have likely stopped versus stuff they would not have detected.

Sure if the were down to £20 versus £15 for RCBO then nobody is going to have a big issue with them, but just now it is going to be a problem for many.

 

[timhoward]

More so when it is a hard sell as to what they really offer in terms of improved safety

There's a certain amount of chicken and egg here, until they end up in more installations we won't see if electrical fire statistics fall in general terms.
What could completely throw the stats is lockdown and the amount of time people spent working at home, and then people returning to workplaces, leading to a rise and fall in domestic fires.

I've had a quick look at some publicly available data:

Percentage of fires, non-fatal casualties and fire-related fatalities in accidental dwelling fires by selected sources of ignition, England; year ending March 2020

So electrical-appliance ignition source caused 13% of fires and accounted for 4% of fatalities.
Electrical distribution ignition sources are in fact killing more people.
(Space-heating source fatalities are really quite scary - people plugging in a fan heater in one room and not running the CH is going to be a real issue)

But maybe more relevant is this graph (same year)
Percentage of fires in accidental dwelling, fires by cause of fire, England; year ending March 2020

My conclusion for now - If 15% of fires are being caused by faulty appliances then maybe our advice should simply be that AFDDs are an attempt to bring down that number. The reality is that we won't know if it works for several years.

What could help would be some government funded TV adverts, like the original "Wake up - get a smoke alarm" campaign.

 

[Markyd]

Looking at about £150 for a RCBO/AFDD all in one unit

 

[Dustydazzler]

Looking at about £150 for a RCBO/AFDD all in one unit

Standard domestic new build looking at around 10-15 circuits

£1500 on devices isn't too bad when you think what the overall build cost is these days

 

[timhoward]

Standard domestic new build looking at around 10-15 circuits

£1500 on devices isn't too bad when you think what the overall build cost is these days

Would you fit them to all though, not just sockets?

 

[Markyd]

Would you fit them to all though, not just sockets?

Prob on 10a upwards

 

[mainline]

There's a certain amount of chicken and egg here, until they end up in more installations we won't see if electrical fire statistics fall in general terms.
What could completely throw the stats is lockdown and the amount of time people spent working at home, and then people returning to workplaces, leading to a rise and fall in domestic fires.

I've had a quick look at some publicly available data:

Percentage of fires, non-fatal casualties and fire-related fatalities in accidental dwelling fires by selected sources of ignition, England; year ending March 2020
View attachment 100501
So electrical-appliance ignition source caused 13% of fires and accounted for 4% of fatalities.
Electrical distribution ignition sources are in fact killing more people.
(Space-heating source fatalities are really quite scary - people plugging in a fan heater in one room and not running the CH is going to be a real issue)

But maybe more relevant is this graph (same year)
Percentage of fires in accidental dwelling, fires by cause of fire, England; year ending March 2020
View attachment 100502
My conclusion for now - If 15% of fires are being caused by faulty appliances then maybe our advice should simply be that AFDDs are an attempt to bring down that number. The reality is that we won't know if it works for several years.

What could help would be some government funded TV adverts, like the original "Wake up - get a smoke alarm" campaign.

I wonder what the percentage of that 15% would have been for ones that have had a proper eicr and pat test done.

In my opinion fit AFDD only where required I think they need to be in the wild for a few more years yet, let's wait and find out what the failure rate is first as there most certainly will be.

 

[Selfmade]

Fascinating conversation folks!

One quick note about some of the graphs others have shown above - I think when they refer to appliances they are not just referring to electrical appliances. So gas heaters for e.g. would be included.

 

[ipf]

Just now a quick search for the Fusebox brand has RCBO for around £15+VAT and AFDD for around £105+VAT, so around £110 extra parts cost per circuit to the customer (inc VAT), and a bit of margin for returns and call outs for odd trips, so say £150.

Not sure what is typical for a home these days, but it is looking like £300-450 extra if you have 2-3 RFC and if not much else (couple of lights, couple of fixed kitchen appliances), then it is probably adding 50% to a CU change?

Some folk won't have issues with the cost but I bet the majority of customers do! More so when it is a hard sell as to what they really offer in terms of improved safety. We see general fire stats quoted from time to time but so far I have not seen an analysis of what AFDD would have likely stopped versus stuff they would not have detected.

Sure if the were down to £20 versus £15 for RCBO then nobody is going to have a big issue with them, but just now it is going to be a problem for many.

Some of the tight landlords won’t like paying 50 squid for an EICR and then 300/400 for a small update repair .

 

[pc1966]

So electrical-appliance ignition source caused 13% of fires and accounted for 4% of fatalities.
Electrical distribution ignition sources are in fact killing more people.

Thanks for looking up those stats.

However, they do not identify the details of it. If it were an arcing break then AFDD would have a good chance of reducing the fires and thus fatalities, however, most of the faulty appliance recalls I remember have been stuff like tumble dryers clogging with lint and catching fire, or fridge-freezers, etc, and they are not going to be helped by AFDD as by time it fails to the arcing point it is well underway as a blaze! A quick search pulled up these:

Which? names 250 fridges and freezers that pose fire risk

Consumer group tells retailers to stop selling models using ‘unsafe’ plastic backing material

www.theguardian.com

https://www.-----------------------.../08/reminder-beko-fridge-freezer-fire-recall/

Total Recalls: How to check if your tumble dryer is a safety risk

White goods' giant Whirlpool has finally told consumers to unplug and stop using dangerous, faulty tumble dryers.

www.london-fire.gov.uk

 

[pc1966]

Ha that’s a good one! Must be a manufacturers video

That image you show saying "cost should not be the major factor" is really condescending and misses the point completely. If we were talking something like £5 extra for AFDD then it might be reasonable, but if it is potentially the difference between £400 and £800 for a CU change (adjusted for your area's affluence) then it is going to make a lot of people thing twice and either not do it, or go to some Dodgy Dave character who offers it for 1/3 the price and makes a complete hash of it.

That is the reality, are you trying to make a few installations a fraction of a percent safer but at the cost of many other being left unsafe or even made more dangerous?

While folks on this forum debate the choices of CU brand and design aspects like dual RCD versus RCBO, the reality is any of you could install any cheap CU and make an old or damaged installation far safer than ignoring it or leaving it to some untrained incompetent.

At least for now for most homes AFDD are options so offering budget and best-case can cover a range of client's ability to pay.

 

[UNG]

That image you show saying "cost should not be the major factor" is really condescending and misses the point completely. If we were talking something like £5 extra for AFDD then it might be reasonable, but if it is potentially the difference between £400 and £800 for a CU change (adjusted for your area's affluence) then it is going to make a lot of people thing twice and either not do it, or go to some Dodgy Dave character who offers it for 1/3 the price and makes a complete hash of it.

Unfortunately it is easy to say "cost should not be a major factor" but for some who are watching the pennies "significant cost is the major factor" in their budgeting for improvements to their property

That is the reality, are you trying to make a few installations a fraction of a percent safer but at the cost of many other being left unsafe or even made more dangerous?

MCB's and RCD'S / RCBO's have over a number of years developed a track record for majorly improving safety. With RCD's / RCBO's it is difficult to quantify the improvement because no one reports or tracks why or when they trip. So moving onto AFDD's who has found, analysed and reported the faults where an AFDD "may" offer a significant safety improvement to an installation

While folks on this forum debate the choices of CU brand and design aspects like dual RCD versus RCBO, the reality is any of you could install any cheap CU and make an old or damaged installation far safer than ignoring it or leaving it to some untrained incompetent.

I have picked you quite a few jobs recently because I will do exactly that, mainly for older people who want a safer installation but don't want the trauma of major renovation work, I'm sure there are a lot who will call me out but while it is not to the letter of the regs it gives the homeowner some piece of mind that they will get a better indication that they have a fault

At least for now for most homes AFDD are options so offering budget and best-case can cover a range of client's ability to pay.

The problem is the "must" and "mandatory" group who force the issue without any hard facts or fault analysis to back up the safety value they offer

How long before we see real world figures that show that SPD's are actually doing their job, offering protection from a lightning strike is a bit of an unknown when you look at the strike risk for an area which depends a lot on the figures you use for the calc. A hospital I used to do a lot of work 20 - 25 years ago at took a strike one Sunday morning causing £450K - £500K of damage one of the hospital engineers was subsequently tasked with doing a risk assessment on future risk of a a strike the outcome of which was they could have a lightning strike once every 42 days or once every 4 years or once every 40 years or once every 400 years depending what factors were applied in the calculation, the cost estimate for the necessary surge protection was £500K - £600K given the most of the buildings were part of a workhouse dating back some 300 - 400 years and there were no records of a strike in the previous 50 - 60 years the decision was to not bother putting the protection in. So were are the historical figures to compare to the theoretical figures to actually assess the risk of needing an SPD on an installation and IMO the same goes for the AFDD how many faults have any of us out on the ground seen where an AFDD "may" have detected the fault an earlier stage than the existing protection devices

 

[Selfmade]

That image you show saying "cost should not be the major factor" is really condescending and misses the point completely. If we were talking something like £5 extra for AFDD then it might be reasonable, but if it is potentially the difference between £400 and £800 for a CU change (adjusted for your area's affluence) then it is going to make a lot of people thing twice and either not do it, or go to some Dodgy Dave character who offers it for 1/3 the price and makes a complete hash of it.

That is the reality, are you trying to make a few installations a fraction of a percent safer but at the cost of many other being left unsafe or even made more dangerous?

While folks on this forum debate the choices of CU brand and design aspects like dual RCD versus RCBO, the reality is any of you could install any cheap CU and make an old or damaged installation far safer than ignoring it or leaving it to some untrained incompetent.

At least for now for most homes AFDD are options so offering budget and best-case can cover a range of client's ability to pay.

Some good points, but it's not just ability to pay, it's also individual choice and priorities. Concepts that are lost on too many in this age we live in.

 

[Selfmade]

How long before we see real world figures that show that SPD's are actually doing their job, offering protection from a lightning strike is a bit of an unknown when you look at the strike risk for an area which depends a lot on the figures you use for the calc. A hospital I used to do a lot of work 20 - 25 years ago at took a strike one Sunday morning causing £450K - £500K of damage one of the hospital engineers was subsequently tasked with doing a risk assessment on future risk of a a strike the outcome of which was they could have a lightning strike once every 42 days or once every 4 years or once every 40 years or once every 400 years depending what factors were applied in the calculation, the cost estimate for the necessary surge protection was £500K - £600K given the most of the buildings were part of a workhouse dating back some 300 - 400 years and there were no records of a strike in the previous 50 - 60 years the decision was to not bother putting the protection in. So were are the historical figures to compare to the theoretical figures to actually assess the risk of needing an SPD on an installation and IMO the same goes for the AFDD how many faults have any of us out on the ground seen where an AFDD "may" have detected the fault an earlier stage than the existing protection devices

So it's anyone's guess. In domestic where I work, people will weigh up all sorts of factors besides the economic - peace of mind vs. potential distress, sentimental value of the equipment that might be damaged, their own personal level of risk aversion etc. etc. And why shouldn't they?

 

[UNG]

So it's anyone's guess. In domestic where I work, people will weigh up all sorts of factors besides the economic - peace of mind vs. potential distress, sentimental value of the equipment that might be damaged, their own personal level of risk aversion etc. etc. And why shouldn't they?

i tink you have really missed the point I was making