120/240 4 wire?

[Frank P. Newman]

I ran into this panel during a recent inspection, but did not expect to find 2 hot conductors, one gray neutral and one bare ground. There was no apparent connection between the neutral and ground. This is not a subpanel, although the main 200A disconnect was outside next to the meter. How common is this arrangement?

[Greg Fretwell]

If the service disconnect is outside this is a sub panel.

[Jeffrey R. Pope]

Originally Posted by fnewman

the main 200A disconnect was outside next to the meter.

That makes it a "sub" panel. The service disconnect is located in the "service" panel. All other panels require a 4 wire feed, with isolated neutrals and bonded grounds (some exceptions apply).

[Frank P. Newman]

Well, I suspected that would be the answer, although I don't always see that arrangement in homes around here. So, here's another question - as you may be able to see from the picture, there are a LOT of neutrals - so many that each could not possibly be landed on an individual terminal. What would be the proper solution for the installer? I would think that a second terminal strip should have been installed.

[Greg Fretwell]

If there are more neutrals than neutral lugs I would be looking closer at the number of breakers installed vs what the panel max is.
You can't mix grounds up with neutrals on the busses in a sub either. There is a ground bus system and a neutral bus system, not connected.
Some panels do have expansion kits for the neutral bus and ground bus expansions are available for virtually any panel.

[Marc D. Shunk]

Originally Posted by fnewman

What would be the proper solution for the installer?

They would install an accessory neutral bar. It is basically another ground bar with insulated standoffs.

[Frank P. Newman]

That is essentially what I told the homeowner (who was present for the inspection). However, I found it interesting that the electrician who did the work carefully terminated the neutrals and ground conductors on their correct bus locations, but bunched the neutrals - I assume out of ignorance because there were a few screws left unused. Given that this is a 40 circuit panel with relatively few 2 pole circuits, the need for an auxiliary neutral bus would seem to be quite a frequent occurrence.

[Marc D. Shunk]

Originally Posted by fnewman

Given that this is a 40 circuit panel with relatively few 2 pole circuits, the need for an auxiliary neutral bus would seem to be quite a frequent occurrence.

Depends on the brand and model of the panel. I can count on one hand the number of times when I've had to add an accessory neutral bar to a panel that I've added circuits to or installed. I've seen a great number of panels, however, that should have had them put in to correct existing nonconformities.