Most of us who have been in the industry for 30 years or more will remember the long discussions on RCDs. In fact, in the 1st Edition of IET Guidance Note 3 Inspection and testing is the statement (2nd para, Section 15, page 81):

In order to test the effectiveness of such devices after installation a series of tests must be applied to check that they are within specification and operate satisfactorily. This test sequence will be in addition that proving that the test button, if fitted to the r.c.d., [sic] is operational.

I remember 'back in the day' there was so much concern about mandating RCDs, chiefly because of their cost (around £80 to £100 in the late 1980's), and the fact no-one trusted them to operate 'as sold'.

The reason we have continued to test RCDs (but not other protective devices) has been ongoing debate about their effectiveness, stemming back to this time. (I'm not, however, saying that all RCDs were always perfect, we all know they have occasionally failed to operate, but no-one seems to care about circuit-breakers which also may suffer from environmental influences on their mechanisms etc.)

I'm sure there will be those who will try and deviate from the following points, by trying to limit the parallels in the discussion on AFDDs. But I think these points are very important:

1. We should not miss the opportunity to introduce protective devices that can save lives and prevent damage to properties. I fully understand cost-benefit debate, but looking back I've heard this before with RCDs.
2. There is an agreed international (and British) standard for these products. That standard has gone through full rigour and public comment process.
3. Because of 1. and 2. above, pseudo-scientific approaches, inductive thinking, etc. used to answer the questions posed in the OP isn't really going to work.

Based on all of the above, I believe the question posed in this thread ought to be turned on its head, and ask the three questions posed on the OP in the following way:

• Is there any evidence that AFDD's would NOT stop these failures?
• What about internal appliance faults - would AFDDs NOT detect them?
• Wasn't Grenfell started in a fridge? If so, would AFDD NOT detect that fault?

Properly researched and supported answers on a post-card please ...

Graham, the parallels you draw with the introduction of RCDs is a red herring, as are your questions which ask the impossible, i.e. to prove a negative.

I have some questions of my own.

Where is the empirical evidence/data gathered by professional investigators which highlight that the lack of a AFDD was responsible for the outbreak of a fire? Or rather, how many fires over the last say, 10 years would have been directly prevented by a AFDD?

How many fires which have been fully investigated, can be directly attributed to an arc fault as being the root cause?

Where is the evidence?

Also, where is the evidence which proves that the decision to mandate the introduction of AFDDs was exclusively driven by sound scientific studies rather than hard lobbying from manufacturers?

Why do the test rigs purposely constructed by the manufacturers rely upon a pre-carbonised element in order to make their device look as if it is actually working properly? Something which is a rare event in the real world of electrical faults.

If the scientific studies were really carried out, then they should be available for public presentation and scrutiny.

Every time I have asked these questions before, I have been deafened by the silence which ensued. Care to make some noise?

Otherwise, all I get are aburpt denials - a bit like Boris denying he had a party at No 10, and we all know how that ended.

Perhaps we ought to start by asking how fires with electricity actually start.

I have provided comment in the past on this Forum, with testimony as a first-hand witness of at least parallel arc that could easily lead to fire, which is swiftly met with "well, we don't wire houses with that cable".

Lots of questions one way, but none the other ...

Which is why I think the parallels with RCDs are very valid.

whjohnson said:

How many fires which have been fully investigated, can be directly attributed to an arc fault as being the root cause?

Where is the evidence?

So,  again, how does electricity cause fires? Above is a post from another contributor, which says a lot about how electrical products and wiring can't cause fires or help them spread, BUT I don't think any of us would doubt that fires in electrical products and installations happen.

whjohnson said:

a red herring, as are your questions which ask the impossible, i.e. to prove a negative.

I'm not asking anyone to prove a negative, I'm asking for some balance in the discussion.

From my perspective, this debate is too much "What have the Romans ever done for us?" at the moment.

gkenyon said:

Based on all of the above, I believe the question posed in this thread ought to be turned on its head, and ask the three questions posed on the OP in the following way:

• Is there any evidence that AFDD's would NOT stop these failures?
• What about internal appliance faults - would AFDDs NOT detect them?
• Wasn't Grenfell started in a fridge? If so, would AFDD NOT detect that fault?

Properly researched and supported answers on a post-card please ...

No, I think that is not the correct approach - that is simply a statement of the null hypothesis.

A manufacturer may be perfectly happy to provide evidence of AFDDs working, but it seems likely that they would keep opposite findings secret. Then of course there is the difference between laboratory tests and the real world.

What we really want is a 2 x 2 contingency table and then apply some simple statistics. Are buildings with and without AFDDs more or less likely to suffer significant fires? So:

gkenyon said:

Based on all of the above, I believe the question posed in this thread ought to be turned on its head, and ask the three questions posed on the OP in the following way:

• Is there any evidence that AFDD's would NOT stop these failures?
• What about internal appliance faults - would AFDDs NOT detect them?
• Wasn't Grenfell started in a fridge? If so, would AFDD NOT detect that fault?

Properly researched and supported answers on a post-card please ...

No, I think that is not the correct approach - that is simply a statement of the null hypothesis.

A manufacturer may be perfectly happy to provide evidence of AFDDs working, but it seems likely that they would keep opposite findings secret. Then of course there is the difference between laboratory tests and the real world.

What we really want is a 2 x 2 contingency table and then apply some simple statistics. Are buildings with and without AFDDs more or less likely to suffer significant fires? So:

Chris Pearson said:

What we really want is a 2 x 2 contingency table and then apply some simple statistics. Are buildings with and without AFDDs more or less likely to suffer significant fires?

Another  consideration is that if the devices might save any lives, they ought to be used?

Although, I also understand the principles of 'ALARP' and 'SFARP' and when they are applied. I also understand when these terms might have been slightly 'confused' in the past - a few hundred £K to some companies might not even compare to a few hundred £ to another - but basing H&S breach fines on turn-over appears to have re-calibrated things a little.

Chris Pearson said:

A manufacturer may be perfectly happy to provide evidence of AFDDs working, but it seems likely that they would keep opposite findings secret. Then of course there is the difference between laboratory tests and the real world.

Again ... perhaps ... we can all speculate But what is, in effect, being said here is that a product standard may not be fit-for-purpose.

Yet, where is the evidence for that?

I'm all for saying how things are ... plain speaking and difficult conversations ... but, how are they actually?