paper romex on an afci

[Ravenvalor]

Hi Folks,

Would you recommend putting the old style romex with the paper jacket and the reduced size equipment grounding conductor on an AFCI circuit breaker?

Thanks,

Jim

 

[480sparky]

Nothing wrong with it.

You may want to megger it first.

 

[Ravenvalor]

afci

afci

Nothing wrong with it.

You may want to megger it first.

Thank you Sparky. The customer will love this good news.

 

[LarryFine]

Jim, just to clarify, what might the concern be?

 

[Ravenvalor]

Concern

Concern

Jim, just to clarify, what might the concern be?

Larry,

An inspector once told me that an AFCI would not work on old BX cable and Knob and Tube wiring. I did not ask him about the 50's and 60's style paper Romex so I just wanted to get other peoples' opinion before making the recommendation to the customer.

Thanks,
Jim

 

[LarryFine]

Unfounded, in my opinion. The wiring type has no bearing on AFCI operation.

 

[Jraef]

Unfounded, in my opinion. The wiring type has no bearing on AFCI operation.

Other than indirectly, given that knob-and-tube or the older BX cable will mean it is pretty old and the insulation may not be good enough to allow an AFCI to hold in...

 

[LarryFine]

Other than indirectly, given that knob-and-tube or the older BX cable will mean it is pretty old and the insulation may not be good enough to allow an AFCI to hold in...

I don't see how poor insulation would affect an AFCI, unless there's severe arcing to ground (sheath, plumbing, etc.)

 

[Jraef]

I don't see how poor insulation would affect an AFCI, unless there's severe arcing to ground (sheath, plumbing, etc.)

Eh... it was a stretch...

 

[flatlander]

I wonder if the lack of a ground with knob and tube will affect the performance of a AFCI?

 

[glene77is]

Larry,
An inspector once told me that an AFCI would not work on old BX cable and Knob and Tube wiring. I did not ask him about the 50's and 60's style paper Romex so I just wanted to get other peoples' opinion before making the recommendation to the customer.
Jim

Maybe not with 40's Romex with the carbon black insulation,
wrapped in paper cord.

I have found enough leakage and induced voltage on 30's K&T so that my Ticker will show 'hot' on the joists, the Neutral, and the Hot.

I have not checked to see if an AFCI would trip over these oldies.

I have very little trouble with 60's Romex with TW insulation.

You will need to set up some sort of test.
And, yes, I need to setup some sort of test, too,
so I'll know for certain what parameters I might be dealing with.

 

[glene77is]

Unfounded, in my opinion. The wiring type has no bearing on AFCI operation.

Unless there is bad insulation and it is leaking, as in small arcing.

I need to setup a test next time I work on one, just to see.
I think my O'scope will show any leaking (arcing) signal.
I don't think the electrical manufacturers have published any standard 'arcing' signal for us to look for. Maybe the whole thing would a possibly complex signal, but I suspect that it will be a hash signal, higher than 1 KHz. But, if it is intermittent, then I may never find it.
I wonder what the digital VOM will show as resistance between conductors. And, the Megger test might be good.

I don't think I got very far with that thought experiment.

 

[LarryFine]

Unless there is bad insulation and it is leaking, as in small arcing.

Well, that's due to a wire defect, not a wire type, and in such a case, the device is doing its job.

 

[don_resqcapt19]

I wonder if the lack of a ground with knob and tube will affect the performance of a AFCI?

It sure will. Most of the trips of an AFCI device are from the ground fault protection part of the circuit and not the fancy arc signature detection part.

 

[Ravenvalor]

fancy arc signature

fancy arc signature

It sure will. Most of the trips of an AFCI device are from the ground fault protection part of the circuit and not the fancy arc signature detection part.

intersting