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View Full Version : Connecting a sub panel and main panel


cmhomeinspect
Dec 19, 2007, 09:27 AM
When adding a sub panel to the main electrical panel, does the neutral bus at the bottom of the main panel have to be removed? If not, are there any specific examples you can offer? Or, should the neutral bus bar be removed at all times?

Thanks & happy holidays,

Mike

hvac1000
Dec 19, 2007, 12:22 PM
When you add a sub panel all the neutrals need to be insulated from the cabinet/panel (insulated neutral bar) and all the grounds need to be placed on a ground bar attached to the metal cabinet/panel. You will have to run 4 wires. Two to carry the two legs of 120 that equal 240 when used together a separate insulated neutral wire and a ground wire.
Nothing attaches these two separate items to each other. The green grounding screw is not used on the neutral bar. It is left out unless used on the ground bar.

Some panels will have a jumper bar between the neutral and the side you will use for the ground side. This has to be removed to comply with the above conditions.

labman
Dec 19, 2007, 12:40 PM
You leave the neutral and ground bars in the main panel alone except for running separate wires from each to separate bars in the subpanel. They should be connected only in the main panel and also to the box with machine screws. Usually you have to buy and add a ground bar to the subpanel. Unlike the neutral, it needs to be connected to it if a metal housing. Buy the kit listed for your panel and install it like the directions say.