ARC Fault C.B. and a funny smell

[Shavner]

I have a question about AF C.B. I have a customer (8 yr old >$1 mill house) that is smelling a buning odor in his bedroom and I belive it may be a low level arc either in a device or in a wire. I've suggested installing Arc Fault breakers on the circuits that feed that room to determine if there is a fault or if it is somthing else. Will this work and is there any other way to trouble shoot for faults in a home (without a megger)? and can I place these breakers on the lighting and switched circuits without giving a false trip on switch arcing? Any info would be appreciated. But I figure that with the new breakers at least if it is a fault then they would greatly increase the life safety of that room.... HELP.

 

[ScottyUK]

If the system can arc, there must be a conductive path to initiate the arc. This might be either ionised gas or a carbon tracking path on damaged insulation. The latter would almost certainly show up on a megger test. I doubt the ionised gas idea is likely in a domestic environment, and would discount it. Borrow or hire the megger and use it. If the owner can afford a $1M house, he can afford the hire charge!

Could it be dust buildup on a luminaire or heater element? Winter is here in the northern hemisphere, and heating systems are being used for the first time since spring (except here, where it is always cold and wet ). Some luminaires, especially some of the architectural halogen types, run at very high temperatures so anything remotely combustible will burn near them.



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If we learn from our mistakes,
I'm getting a great education!

 

[logbook]

Shavner,

I don’t suppose many people have experience with arc fault circuit breakers yet because they appear to be very new. I had not heard of them before you mentioned them; I thought you had confused the name.

Series arcs will not show up on any test equipment other than an AFCB. That is the whole point of Canada requiring them to be fitted under the new Code. Parallel arcs between the phase and neutral will likewise be undetectable, even with a Megger, unless you disconnect all equipment and do a full wiring inspection. An AFCB which trips on light switches is not a valid product and would be returned to the shop as "not fit for the purpose".

The customer is right to be concerned as this is a potentially hazardous situation. An additional approach might be to isolate the lighting circuit and see if the problem remains after a day. Likewise with the power socket circuit on a different day.

The customer should also be concerned that you apparently don’t have the appropriate test equipment. I understand that you may be "just trying to help out", but not having and using the appropriate equipment (Megger/earth fault loop impedance tester) is not helping anyone.

 

[stevenal]

Try an IR camera.