Main Panel or Subpanel?

When the service cable runs from the meter to an exterior disconnect, then through the wall to the indoor panel, does the short piece of service cable that runs through the wall have to include a ground (or can it just be 2 hots and a neutral)? And does the answer change if the exterior disconnect is a breaker rather than just a switch?

I’m asking because I sometimes see an exterior 150-200Amp breaker (or maybe it’s just a switch/disconnect) and then on the other side of the wall I see a 150-200Amp breaker in the panel.

It seems to me if the wire through the wall is 2 hots, a neutral, and a ground, then the indoor panel becomes a subpanel that must have separate neutrals and grounds. Whereas, if the wire through the wall is just 2 hots and a neutral, then the indoor panel does not need to have grounds and neutrals separated.

The “service” ends at the first OCPD (the exterior disconnect, if there is one). All panels after the “service” are remote distribution panels or sub-panels. When the first OCPD is on the exterior then the feeder running inside needs to be 4 wire. However, keep in mind, a metal conduit from the first OCPD to the panel inside can serve as the ground (EGC).


Yes, that is correct, Peter.

Or, like Simon said , a metal conduit can serve as the EGC.

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Is the exterior disconnect just a switch or does it provide overcurrent protection? That would change the service point.


Good point, Jim…

If they are separate, the OCPD has to be right next to the switch or in the same enclosure.

An exterior disconnect could satisfy the 2020 requirement for an emergency disconnect without being the service. The service could still be inside.

Hey guys, thanks for all the responses!

After reading the replies and doing more research, it seems if there is an external breaker (overcurrent device) there will either be a bonding conductor OR a metal conduit that bonds, the external panel to the indoor panel, and the indoor panel becomes a subpanel that must have separate neutrals and grounds. regardless of whether or not the inside panel contains a 150-200Amp breaker.

But if the external disconnect is just a switch and not a breaker (overcurrent device), the indoor panel is not a subpanel, so it does not need to have neutrals and grounds separated.

In this second scenario, I’m guessing there would just be 2 hots and a neutral going though the wall and metal conduit would be used to bond the external switch panel to the internal panel, right?

Edit: It seems from this picture that the GEC could go in 3 different locations, but there appears to be some debate online about whether or not an external switch/disconnect (not an overcurrent device) is considered a “service disconnect” according to the NEC.
Elec - GEC graphic

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In the first example you would have a feeder between the service disconnect and the panel that would make the conductor between the two an equipment grounding conductor (EGC).

In the second example the raceway is not used to bond the two together the neutral is bonded in both enclosures.

Thanks Robert! For some reason I had it in my head that “EGC” was just used to describe the conductor from the grounding bar in the panel to the ground rod, but I guess we also use that term for grounding feeders to subpanels.

A GEC would connect the grounding electrode to the panel, an EGC is run with a branch circuit or feeder. There are different EGC’s that are not a wire type, could be a metal raceway. I know that this alphabet soup is confusing. :slightly_smiling_face:


You also need to differentiate between the neutral to ground bond found at the service and simply using a metallic conduit as a ground means.

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