This new thread expands on this one:

Rescue Work Near Miss

After disconnecting the faulty circuit the other day, and re-doing the bond yesterday, I went ahead and installed AFCIs today, which took some work because I had used a multiwire to feed the two circuits in a junction box. So I added a cable to the junction, split up the neutrals and hots and nutted off the red wire in the 12-3-G.

First I measured again for resistance to ground from hot to ground on the faulty circuit. 14 Ohms. Wow, that translates to roughly 8.5 Amps, not enough to open a normal OCPD.

I connnect the normal Breaker in and turn it on. No tripping, no noise, nothing. Measure amperage, Hmmmph. Nothing!

Replace with the AFCI and it holds. Then I turn on a light and it trips. OK, the second part was expected but I'm still confused.

Measurements of the fault were 114V from door threshold to cover screw on panel. This was before the bond repair, which dropped it to 0V.

I really expected to see some current (say 8.5A) when the circuit was energized and I expected subsequently, that the AFCI would trip instantly do to the ground fault.

What in the world is going on here, and does it help me in any way to locate the fault?

I gotta start tearing out walls and siding the next clear, sunny day.

[Linked Image]

Anyway, so far, this application makes me glad that AFCIs are available, I just wish they'd do more...


-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI