Why would a regular breaker work where a afci breaker won’t?

[Chickenfriedblake]

Why would a afci breaker trip with under 4 amps but a regular breaker works fine?

 

[littlespark]

A regular breaker is only looking for over current…. Whereas an afci will detect an arc…. Meaning a loose connection somewhere on the circuit.

 

[SparkyChick]

You might also want to check if your AFCIs include the same functionality as GFCIs. Certainly here in the UK it seems they do, if it's the same in the USA as @littlespark says, could be an arc on the circuit, or it could be a ground fault.

 

[Chickenfriedblake]

I ran the test and according to the breaker instructions there is a ground fault . I went through every box and connection couldn’t find it. Thanks little spark

 

[SparkyChick]

So... if I was investigating this fault for a client, I would be asking the following questions...

Have you had any work done on the property in the vicinity of the cables/accessories it supplies?
Have you hung any shelves or pictures immediately before the fault developed?
What's connected to the circuit? It's possible, if something is plugged in that it's responsible for the fault
Have you got any outside lights supplied by this? If so, have you checked that there isn't a bunch of water sitting in them?

It's important to realise that a ground fault could be between the hot and ground or the neutral (I don't know what it's called in the USA) and ground. Could be as simple as a tiny pinhole/nick in the cable insulation where it was pressed up against a metal back box.

If you get an electrician in, hopefully they'll have a tester capable of carrying out insulation resistance tests which should allow them to identify which conductors are involved in the fault.

Don't keep resetting the breaker... if it's a sizeable fault (hot to ground for example), it's possible that repeated energisation could blow the ground conductor away. The net result of that would be that the breaker may stay on but everything after the fault could have lost it's ground and thus become unsafe.

 

[Chickenfriedblake]

I did do resistance tests on the runs I thought might be culprit. Thanks.
That’s so cool they can meter and math current . It’s like a little electrician living in your panel

 

[davesparks]

It's important to realise that a ground fault could be between the hot and ground or the neutral (I don't know what it's called in the USA) and ground.

As far as I know the term neutral is commonly used in the USA but the correct term is grounded conductor.
So in their code (regulations) they have the grounding conductor (earth) and the grounded conductor (neutral)

Which is just as good as us with the line and neutral both being live.

 

[SparkyChick]

@davesparks ... nice to see you putting in an appearance again. Hope you're keeping well

 

[Chickenfriedblake]

Mistral and ground tie together at the breaker here. They didn’t add ground wires until the 60’s I think. You have to have two wires because of magnetism I think