AFDD

I have no results to add I'm afraid, but I'd also be very interested in any information your investigation  turns up as well. AFDDs have been in use in the USA for a while  but even there, it seems there is very little published, and even if there was, their wiring practices are so different (110V, wire nuts, breakers at the socket rather than at the board, far less test and inspect) that it would be difficult to read across into the effect into our  230V land. 

As you might expect the makers literature tends to give the impression that we'll all be burnt to death without them but there is very little objective data, and to be fair they are not very common in the sort of installations that have the most fires, which tend to be domestic, and the few places they are mandated tend to already have some maintenance supervision anyway.

Mike

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.

Hi Mike! 

Thank you very much for your interesting response and comment!

I think the AFDD can be a very good device for safety protection but the demand has been quite small because of the relatively high price.

When I discussed with some manufacturers, they advised that the price of AFDD could be around 5 % of the current level if the demand was 

large enough. This is a chicken and egg situation. As an engineer, we always put consumer safety as our first priority and I would sincerely 

invite suggestions on how to convince the relevant parties to work together to encourage the use 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.

Albert Law said:

As an engineer, we always put consumer safety as our first priority and I would sincerely 

invite suggestions on how to convince the relevant parties to work together to encourage the use of AFDD. 

I agree on the importance of consumer safety and that requires safety improvement measures should be based on evidence, to allow an analysis of costs and benefits to determine which safety threats are the most significant and which measures / controls provide the most cost effective improvements in consumer safety.

For example, it could be that other causes/mechanisms of electrical faults/fires are a greater safety risk, that other engineering improvements / control measures could provide greater safety improvement, or at lower cost than AFDDs. 

Probably the single most effective safety measure for protecting consumers against electrical fires and fires in general, is having a working smoke alarm, preferably a hard-wired one to ensure it remains powered 24/7, but while these are encouraged they are not mandatory for existing, privately occupied homes. We cannot assume that encouraging AFDDs is the most effective measure to aid consumer safety, it might be that taking a stronger line on smoke alarms and bringing requirements for provision and testing of wired smoke alarms the scope of the Wiring regulations would provide greater overall benefits at lower cost.

I found this report looking at fire incidents in Merseyside,and what jumps out as I guess you might expect, electrical fire injuries are only a small proportion of total fire injuries, so as Electrical engineers we have to be careful not to operate and think in a silo, assuming our area is the most important, when it may be other safety threats require more attention.

researchonline.ljmu.ac.uk/.../Electrical Home Fire Injuries Analysis.pdf

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).