AFI Problem (Very interesting)

Hikyuuri

Hello. I am having a very interesting problem with arc fault breakers. We have arc fault breakers in our panels according to code, and everything is up to par (so the builder claims). However, we are having a very interesting problem.

First, a little background.

We have a 200A main panel and 2 100A sub-panels. Both sub panels go directly back to the main panel via 2-2-2-4 aluminum wire, and I know both sub panels are wired correctly as I wired them myself.

The main panel was completely wired by our builder's electrician, and did everything but the 2 sub panels. He installed arc fault breakers everywhere they were needed, and everything looks correct.

Now, for the problem. If one of the circuits in the sub-panel in our basement has an arcing problem (bad light switch in the circuit), instead of the arc fault that the switch is wired through tripping, arc fault breakers in the main panel trip instead. These breakers have nothing to do with the circuit that was actually arcing except for the fact they come from the same electrical main.

What concerns me is, like I said, the switch is on an arc-fault breaker that tests just fine with its built in test button. Why is that breaker not tripping? Why is it causing other breakers in the house to trip instead? Did our builder's electrician really mess something up in the main panel?

Also, as a side note, one of the breakers in the main panel that trips when the switch on a different circuit arcs has tripped a lit ever since the house was built. For a while, it was almost 2 times a week we would be resetting that breaker. It has not had a problem though for almost 3 months, which we thought was caused by us getting a high-end surge suppressor for our AV equipment. However, it makes me wonder if the real problem is that something is not wired correctly, and the AFCI's are either not tripping when they should be, or are tripping because something else is arcing.

Does anyone have any ideas for me asto why this could be?

I can provide any pictures that people require to see how things are wired!

Thanks!

kbsparky

Have you tried replacing the errant breaker?

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frenchelectrican

I was thinking some case some AFCI breakers are not set up correct and just wondering what brandname breakers you have them in there ?

Merci,
Marc

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The answer will be based on NEC ( National Electrical code ) or CEC ( Cananda Electrical code ) or ECF ( Electrique Code France )

deverson

I had an arc fault breaker that kept tripping in a dorm room. the breaker indicated it was a neutral to ground fault.I opened the panel and found the neutral buss loose and had overheated. Not sure why a breaker downstream tripped but it did. Panel interior had to be replaced as there was some arcing. Lucky that's all that failed!

Hikyuuri

Thats the problem. The breaker that should be tripping is not tripping. Instead, other breakers that have nothing to do with the arcing circuit are tripping instead.

I thought about replacing the breaker on the arcing circuit to see if it trips instead, but that still leaves the question of why are breakers that have nothing to do with the arcing circuit tripping instead.

Sorry, I guess I did forget that bit of information. We are using Siemens load centers with Siemens AFCIs. In fact, all of the breakers are Siemens.

eastcoastsparky

[QUOTE="Hikyuuri"]Hello.

We have a 200A main panel and 2 100A sub-panels. Both sub panels go directly back to the main panel via 2-2-2-4 aluminum wire, and I know both sub panels are wired correctly as I wired them myself.



Thanks![/QUOTE

you sound pretty confident of the sub panel you installed, but just a thought are you sure theres no mistake on your end, a loose nuetral from sub panel feeders

Hikyuuri

Yeah, I double checked the torque on all connections, both in the sub panel and the main panel. Everything is torqued to where it should be.

Just a thought, in the sub panel I installed, it originally only came with one neutral/grounding bar, so the neutrals would share with the grounds. I decided to go and buy a 2nd bar so the grounds are isolated from the neutrals, so both have their own bar, and their own wire back to the main panel.

Now, in the main panel, the builder's electrician did not appear to be as concerned with keeping the grounds and neutrals separated, and wired everything up to wherever the closest bar was. When I installed the sub panel, I put the neutral wire right next to the ground wire in the main panel. Could that be part of the problem, that the neutrals and grounds are not separated in the main panel for all the circuits?

curiousB

Did you remove the bonding screw in the sub panels so that the neutral buss is floating from chassis ground?

Not sure that would do anything in afci situation you have but just double checking

eastcoastsparky

they are find to be both connected in the main to the nuetral bar, but it is important to have them separate in sub, so its a good thing you went out and bought a ground bar

Hikyuuri

Yeah, I made sure to remove that screw so the neutral is isolated from the ground.