MAIN Panel Question


Old 02-19-05, 03:14 PM
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MAIN Panel with 2 neutral/Ground bars

I'm adding a subpanel in my home and I've got everything done except connecting the wires to the Main Panel...

I have 4 wires of #6 thickness(Red, Black, White, and Bare) ran between the main and subpanel (3 feet away from each other). (The subpanel's neutral and ground are isolated, IE no strap connects the two.)

When I opened up the main panel I see from the service: the normal Black and Red coming in. But I see 2 more wires coming in. One is all white that connects to a bar and the wire to it has the same thickness as the black and red. The other is a black wire marked with white tape that connects to another bar and the wire to it has the same thickness as the red and black. Both bars have both white and bare wires running to it. And in fact white and bare wires are run to the same hole in the bar.

1. Does it matter which neutral/ground bar I connect to? (Remember 1 has a large feeder to in and the other has a small feeder to it)
2. Do I need to connect the white and bare together in one bar's hole or should I use two holes? (Not sure if they both will fit into 1 hole.)
3. Is the neutral/ground bars live even if the Main breaker is turned off? (Dumb question but I don't want to die. )

Thanks for any answers or suggestions.

Last edited by chrishallowell; 02-19-05 at 07:36 PM.
Old 02-19-05, 06:44 PM
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You should not have white nautrals and bare ground wires in the same hole, as that violates code. If the panel allows, it is okay to have two ground wires in the same hole, but never more than one neutral wire per hole.
Old 02-19-05, 08:43 PM
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The main panel has a grounded conductor (white) that lands on the neutral bus bar. From there you can land both grounded (white/netural) and ground wires to this buss. And yes some panels are labeled to land more than one of each type into a single hole (terminal). It sounds as if your POCO should be contacted as you will almost never see entrance cables that are black and red, they would just be black. The other issue is the two grounded conductors, this also does not sound right, your set up sounds like your main is a sub panel from other building. Is your incoming lines coming from a pole mounted transformer? In running a sub panel you would only run the supply lines (black) the grounded conductor (white) and a ground wire bare or insulated (green). In the sub panel the grounded conductor must land on an insulated bus bar seperate from the ground and panel. The ground wire lands on a non-insulated bus bar bonded to the panel and a grounding system will need to be installed and bonded. This can be one or more ground rods and if the local jurisidiction requires the ground will be bonded to the water pipe (iron) or rebar imbedded in the slab.
Old 02-20-05, 06:21 AM
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I misspoke

I mis-spoke when I said a red and black coming into the main panel. I rechecked that and they are both black coming in.
Does it matter which neutral/ground I add a new breaker to?

Also I have read elsewhere that the ground in the subpanel should connect back to the main panel; thus only 1 central ground because both panels are in the same building. Is this true?

I look forward to your comments/suggestions.
Old 02-20-05, 08:36 PM
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If the new sub-panel is installed to provide power to the same building (house) in say an addition then yes. Be sure that both the panels are bonded together and that the appropriate neutral and ground wire is ran also to the sub-panel. Are you using a main lug or main breaker type sub-panel? One other question is, have you done a load calulation for the main and sub panels? Is your current service large enough to support the addition load (circuits)?

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