AFDD

Albert Law said:

Is it proven on enhancing electrical safety and is it worthwhile on the additional cost involved ?

To the best of my knowledge, the UK does not record fire safety statistics for electrical installations to an appropriately granular level to assess this properly.

Hi Gkenyon!  

Thank you so much for your kind response.

In Hong Kong, we are preparing to use AFDD on a wider scale but we find it difficult to justify the very high cost involved.

I would suggest that some universities in the UK or other countries will carry out research on the justification of application of AFDD in collaboration with the major manufacturers of AFDD.

Albert Law said:

I would suggest that some universities in the UK or other countries will carry out research on the justification of application of AFDD in collaboration with the major manufacturers of AFDD.

If there is a driver to do so? I have not come across any, but I guess an internet search would reveal any prior or in progress research if you are looking for that?

USA was first to implement, so if there is any data, it would be there.

Its not what you want to read I suspect but a few years ago now a chap from CIBSE did some independent experiments and analysis It seems that his paper has now escaped onto the internet, so I link to it here  Arc Fault Devices Are they worth it?

His conclusion was as above that there  is not really a lot of evidence. Actually the conclusions are more than equivocal about the claimed 'advantages', and sort of suggests that at best they only detect a very limited range of dangerous situations, (".. verification tests are quite artificial, and there appears a disconnect between  BS EN 62606’s verification procedure and real faults..") and comments that in terms of fire safety we'd probably do better replacing PVC with XPLE cable... Apart from that it is a pretty ringing endorsement. Ha !

Mike.

Ideally, a randomised controlled trial is required. So take a new development and randomly assign 50% of dwellings to get AFDD and 50% not.

Then observe. Given the rarity of electrical fires, even with a whole new town, it might take a long time.

If anything less than a randomised controlled trial is performed, it is going to be difficult to exclude obviously biassing factors. So, installations with AFDDs will be newer than those without, the owners/occupants may be more risk averse and use other means to reduce the risk, and so on.

mapj1 said:

Its not what you want to read I suspect but a few years ago now a chap from CIBSE did some independent experiments and analysis It seems that his paper has now escaped onto the internet, so I link to it here  Arc Fault Devices Are they worth it?

Given the current thread debating the merits of the ring final circuit, makes an interesting point about the ring removing the voltage difference across a conductor break, so preventing series arcing faults.

mapj1 said:

Its not what you want to read I suspect but a few years ago now a chap from CIBSE did some independent experiments and analysis

I've definitely read this? (Although mapj1  I understand if this wasn't aimed at me, just the post said 'in reply to gkenyon ')

I'm also not sure it's correctly attributed to CIBSE affiliation ?

Happy to let everyone draw their own conclusions ... but at the end of the day, I'm firmly of the opinion that any comments about the performance, operation, relevance or need for the device ought to be aimed at BS EN 62606 and IEC 62606 ... BS 7671 is not, after all, a product standard (and nor is IEC 60364 series).

gkenyon said:

Happy to let everyone draw their own conclusions ... but at the end of the day, I'm firmly of the opinion that any comments about the performance, operation, relevance or need for the device ought to be aimed at BS EN 62606 and IEC 62606 ... BS 7671 is not, after all, a product standard (and nor is IEC 60364 series).

BS 7671 is stipulating that AFDDs "shall" be used in some situations and generally "recommended" in other situations (421.1.7).

This is a moderately serious regulatory intervention, directly changing wiring practices with direct financial costs being imposed on the end-consumer.

To state the obvious, there must be some evidence base, a safety incident analysis, a cost-benefit calculation to justify the imposition of this requirement. 

Presumably the committee responsible for deciding to add that requirement into the BS 7671 must have that evidence and analysis, does anyone know where that is recorded? 

gkenyon said:

Happy to let everyone draw their own conclusions ... but at the end of the day, I'm firmly of the opinion that any comments about the performance, operation, relevance or need for the device ought to be aimed at BS EN 62606 and IEC 62606 ... BS 7671 is not, after all, a product standard (and nor is IEC 60364 series).

BS 7671 is stipulating that AFDDs "shall" be used in some situations and generally "recommended" in other situations (421.1.7).

This is a moderately serious regulatory intervention, directly changing wiring practices with direct financial costs being imposed on the end-consumer.

To state the obvious, there must be some evidence base, a safety incident analysis, a cost-benefit calculation to justify the imposition of this requirement. 

Presumably the committee responsible for deciding to add that requirement into the BS 7671 must have that evidence and analysis, does anyone know where that is recorded? 

TurboGen said:

This is a moderately serious regulatory intervention, directly changing wiring practices with direct financial costs being imposed on the end-consumer.

It's definitely not a 'regulatory intervention' ... that would require legislation!

TurboGen said:

To state the obvious, there must be some evidence base, a safety incident analysis, a cost-benefit calculation to justify the imposition of this requirement. 

Presumably the committee responsible for deciding to add that requirement into the BS 7671 must have that evidence and analysis, does anyone know where that is recorded? 

All I can say to that, is that it's been through public consultation (multiple times) and rigorous debate ... I've added something to a subsequent reply that might be of interest, that is in the public domain.

TurboGen said:

To state the obvious, there must be some evidence base, a safety incident analysis, a cost-benefit calculation

I tend to disagree with the "MUST" aspect.

We shouldn't need to kill people first, so as to gather evidence to allow our selves to be safer. We do have to match that tendency to being scared of our own shadow, to decide about ALARP (as low as reasonably possible), or other 'value of a life' etc. financial measures of safety.

It is a 'gamble'. We are happy to pump prime commercial industries for gain (the early funding for wind power, solar power, etc), where that investment creates rapid learning with scale benefits, so we should be able to do the same with safety systems.

Philip Oakley said:

I tend to disagree with the "MUST" aspect.

We shouldn't need to kill people first, so as to gather evidence to allow our selves to be safer. We do have to match that tendency to being scared of our own shadow, to decide about ALARP (as low as reasonably possible), or other 'value of a life' etc. financial measures of safety.

To make something safer, requires that there must be some level of unsafety, some risk, some hazard or danger to begin with, and further it requires that whatever action we propose to take will somehow reduce that risk or danger. 

Evidence does not require us to wait until people are killed or injured, the Accident Triangle principle of identifying near-hits, low level events that point to the risk of more severe events occurring in future, is still good evidence toward justifying action.

If we're then going to make some intervention, then to know it actually improves safety requires some evidence that it is effective, that it does indeed reduce the danger or risk, otherwise we could pursue ineffective and ultimately pointless activities, when our efforts and expenditure would have been better spent on other more effective measures. Again, that does not require us to wait for severe events, deaths injuries, the evidence could come from testing, trials, sampling or other methods.

But to go back to your key point "to allow our selves to be safer" well if we have no evidence of there being a hazard, a risk and we have no evidence that what we propose to do will effectively reduce that hazard or risk, then have we really made anything safer? Arguably we may have been better searching out and focusing on other safety hazards.

Philip Oakley said:

It is a 'gamble'. We are happy to pump prime commercial industries for gain (the early funding for wind power, solar power, etc), where that investment creates rapid learning with scale benefits, so we should be able to do the same with safety systems.

Today, we already have a number of highly effective safety measures which are not universally used, for example smoke alarms, probably one of the most powerful and effective measures to prevent deaths by fires. A quick check, shows Government statistics indicate 20% of all electrical fires occur in houses without a working smoke alarm, greatly increasing the risk of injury and death.

So if our goal is to improve public safety, wouldn't you start by amending the Wiring Regulations to stipulate that in every domestic property at least one hard-wired smoke alarm shall be installed, connected into the fixed wiring, either a lighting circuit, or a dedicated smoke alarm circuit where available to provide protection against electrical fires, and all fires in general.

That is likely to be a far more effective safety measure, and provide a far better cost-benefit outcome than AFDDs.