Does AFCI breaker require the same neutral wire as the protected circuit?

[sgarson]

Have just upgraded an old Zinsco breaker panel. All the wires coming into the panel are individual and there is no way to know which neutral wire goes to which black hot wire, without extensive testing. Just a spagetti of black, white and ground wires come into the panel via a 2-inch conduit, versus NM cables, which are probably in the wall and hidden.

Can an AFCI breaker be used in a situation like this? Or does the AFCI require the neutral that is actually used for the circuit being protected. Obviously, all the neutrals are bonded together.

Thanks!

Steve

 

[Little Bill]

If this is a single pole AFCI breaker and it contains a form of GFP, then it won't set or work without the circuit neutral landing on it.

 

[sgarson]

If this is a single pole AFCI breaker and it contains a form of GFP, then it won't set or work without the circuit neutral landing on it.

Thanks. I thought that was the case. it feels like a crime to not use AFCIs for a panel update, but I'd have to disconnect every neutral and spend a day or two testing the circuits. Is it the same story if the AFCI has no GFP?

 

[don_resqcapt19]

Thanks. I thought that was the case. it feels like a crime to not use AFCIs for a panel update, but I'd have to disconnect every neutral and spend a day or two testing the circuits. Is it the same story if the AFCI has no GFP?

There are AFCIs from at least two companies that do not have GFP protection. GE, and one of the Eaton lines.

 

[winnie]

As Don notes, there are AFCIs that do not have GFP protection.

Assuming (really bad assumption for old wiring) that there are no 'bootleg' neutrals, you can pair hot and neutral by measuring from the panel.

Hot and neutral should carry the same current. When both a hot and its associated neutral are in the clamp then you should net zero current. For 'multi-wire' circuits, all conductors together should net to zero.

If you can put a 'flashing' load on a circuit, you can probably locate it and the corresponding neutral pretty quickly.

-Jon

 

[mopowr steve]

Siemens/ITE no longer have gfp in their breakers,
As a matter of fact if you use one of the newer plug on neutral panels the plug on neutral afci breakers don’t even have a neutral load screw on them. In which case would be great in your situation.
As long as you don’t need any Dual Function breakers in which case there is a load neutral terminal.

 

[sgarson]

If I put a load on one circuit and use a clamp-on ampmeter to measure the load, would the clamp-on meter record the same load if I clamped on the neutrals one-by-one, while they are still connected to the grounding bus?

 

[winnie]

If I put a load on one circuit and use a clamp-on ampmeter to measure the load, would the clamp-on meter record the same load if I clamped on the neutrals one-by-one, while they are still connected to the grounding bus?

In general yes. All current going on on a 'hot' must return somehow, and as long as there are no ground faults and no 'crossed' circuits that somehow must be the neutral associated with the circuit.

-Jon

 

[retirede]

If I put a load on one circuit and use a clamp-on ampmeter to measure the load, would the clamp-on meter record the same load if I clamped on the neutrals one-by-one, while they are still connected to the grounding bus?

Yes, again presuming there are no neutrals tied together someplace creating a parallel neutral path.