Some questions around AFDDs

[InTheHighlands]

I'm not an electrician, but take an interest in what's happening to the electrics in my house. My electrician who is a personal friend has alerted me to AFDDs - of particular interest because I live in a remote area in a wooden panelled house with plenty of evidence of hungry mice. My CU is a Crabtree Starbreaker with a full set of miniature RCBOs. I've tried to speak to Crabtree re questions 2&3, but with no success yet. So can I ask 3 questions here:

1) Why do the latest regs suggest the use of AFDDs only for circuits with sockets? As, presumably, lighting, cooker etc circuits are perfectly capable of arcing. Is this pragmatism - cost vs likelihood?

2) When the AFDD trips, a handy sticker will show it flashing - 1x arc detected, 2x over-voltage, 3x residual current. But no indication of tripping on overload - does one assume that no flashes = overload? I'd prefer something more positive!

3) When the AFDD trips, does it hold the trip cause until reset, regardless of time? And any intervening power cuts?

Depending on answers to above, if I come home from a long holiday to find one circuit tripped, but no indication when resetting, what next?!

Thanks for any thoughts!

 

[newfutile]

You can fit Arc Fault Detection Device where you want not just sockets,some loads may not be enought to trip them,different makes show different patterns of lights,Hagar connects to an app to tell you the fault,though some have said bad things about the Hagar.

 

[buzzlightyear]

• Regulations:
  While not mandatory in all domestic situations, recent amendments to electrical wiring regulations (like the 18th Edition in the UK) recommend or require AFDDs in specific high-risk residential buildings.

 

[Avo Mk8]

1) Why do the latest regs suggest the use of AFDDs only for circuits with sockets? As, presumably, lighting, cooker etc circuits are perfectly capable of arcing. Is this pragmatism - cost vs likelihood?

AFDD's apparently only respond to arc faults over 2.5A, (because that's when sufficient energy becomes available in the arc to damage/set alight cable - apparently!) and will ignore faults below that current. Hence no point in using on many lighting circuits (apparently!).

2) When the AFDD trips, a handy sticker will show it flashing - 1x arc detected, 2x over-voltage, 3x residual current. But no indication of tripping on overload - does one assume that no flashes = overload? I'd prefer something more positive!

The indication you have is that it's tripped - if the indicators are not showing a cause, you are back with "it's tripped", just the same situation as with your MCB or RCBO. They don't tell you what's wrong either!

3) When the AFDD trips, does it hold the trip cause until reset, regardless of time? And any intervening power cuts?

Supposed to, but any indicators provided are up to the manufacturer to determine - I gather they are not in the product standard for AFDD's, and there is no common agreement between manufacturers as I understand it.

Depending on answers to above, if I come home from a long holiday to find one circuit tripped, but no indication when resetting, what next?!

I think there may be whizzy 'smart' AFDD's that can be set up with a hub to message you with what's wrong etc, so if you "invested" in those, you might know even - while you were on holiday.
Is that progress ?

This answers some questions, but maybe not the one's you are interested in
https://www.electriciansforums.net/...ult-detection-afdd-faq-fact-sheet-pdf.119810/

PS just to say I remain to be convinced about the value of AFDD's in a well maintained property., though I can envisage old installations where they could add value. With relatively modern properties, as long as the electrical installation is regularly inspected, screw terminals kept (correctly) tight, advice followed, domestic appliances and cables looked after etc. I wouldn't loose sleep over not having AFDD's.
️️

 

[InTheHighlands]

Thanks, especially Avo Mk8. That all seems to reinforce what I'd gleaned from reading various threads.

2.5A is interesting, with all circuits protected at higher thresholds.

The Crabtree Starbreaker versions are not able to talk to you.......

Meanwhile, spotted another nibbled cable, and our ancient cat shows no interest in earning her keep.

I imagine prices will drop with wider adoption - and that may lead to "tightening" standards.

I'll ask my electrician to keep an eye out - and, if he's happy to fit them, I'll see what Ebay etc has to offer for brand new items for our socket circuits first.

 

[Avo Mk8]

Meanwhile, spotted another nibbled cable, and our ancient cat shows no interest in earning her keep.

We had a squirrel family set up home in the roof of our Edwardian house, and one of them found a way under the upstairs floor to make a home. Long story short, a small fire ensued to which the fire service quickly responded, so fortunately no major damage. I was amazed at how much insulation had been stripped from the cables - all three conductors in multiple T&E's bare for more than a foot in places.
That property had a Wylex fused 'wooden edge' CU, quickly replaced by a dual rcd type after that experience, there being no AFDD's back then.
In your situation, I would encourage you to have at least an all RCBO board, or indeed AFDD's, and a blitz on rodents!

I noticed my previous link didn't work! Here it is, though it's getting a bit out of date maybe.

https://www.electriciansforums.net/attachments/beama-guide-to-arc-fault-detection-devices-afdd-pdf.45459/