Commons Clamped together

[EricS]

Saw a sub panel back fed by a 100amp breaker in the main. The common from the sub and common from the main where clamped togther in the main panel. Is this okay? I ask because we came across serveral outlets powerd by the sub that were not reading a ground. Could the two commons being together cause a false read?

Thanks

Eric

[hausdok]

When you refer to "commons" are you referring to the equipment-grounding conductors ("grounds" - bare or green wires) or to the grounded conductors ("neutrals" - white wires)?

ONE TEAM - ONE FIGHT!!!

Mike

[EricS]

The neutral white wires

[hausdok]

OK,

Now I think I'm forming a picture; the grounded (neutral) conductor from the sub-panel is secured under the same lug in the main panel as the grounded conductor from the service entrance.

As far as I know, it's not OK to do that. First, a lug has to be rated for two conductors and second there is rule that grounded conductors will each have their own little seat on the bus. There should have been another lug somewhere on the neutral bus in that main panel to which the grounded conductor from the sub-panel feeder can be attached.

ONE TEAM - ONE FIGHT!!!

Mike

[EricS]

Thanks Mike

[John Kogel]

The grounding or lack of it should not be related to the doubled neutrals except for one thing - both are signs of amateur attempts at wiring. I'd call for a qualified electrician to inspect the whole setup.