View Full Version : expand electrical box

October 22nd, 2002, 10:38 PM

I am starting work on finishing my basement and I have wired in some outlets and switches downstairs. However, I want to make them their own circuit. I have room in my electrical box to expand and add another circuit breaker, but there are these steal bars, I believe they are called "Neutral Bus Bar", that the white and copper wires join to. Anyway, those are all full and I need to expand on that. Also, I was reading that if two bars exist one is often used for the white wires and other one used for the copper, but my two mix and match. I was wondering if it is necessary to expand the "Neutral Bus Bar", or can I simply use an existing hole even though there already are wires in it. If I must expand, what is the best way to do that. I am trying to explain the situation the best I can, please bear with me.

Thanks for your help!

October 23rd, 2002, 07:00 PM
You were clear and precise in your question, I could have not asked your question for you any better than you did. Congrats you did fine.

The neutal bar and grounding bar in your panel is wired in different manners depending on whether you have a main service rated panel or a sub panel [slave from a main panel]

A sub panel must have the white neutral wires on the neutral bar and that nuetral bar must be isolated from the metal case of that subpanel and that neutral bar must be isolated from that grounding bar. Teh whites must go on that isolated on plastic neutral bar in a sub panel. The bares and green wires would be connected only to the equipment grounding bar that also must be bonded ot the metal case of that sub panel that gets its power from another disconnect or panel.

A main service rated panel is the panel that has the main braeker in it that is directly connected to the meter base of the utility company.

This main service rated panel must have both the neutral bar and the grounding bar married together as one entity. The whites, bares and green wires may be intermixed on either bar because they are made as one bar by a jumper joining both the neutral bar and grounding bar. Then the metal case of that main service rated panel must then be bonded to either the neutral bar or grounding bar.

If your white neutral and bare or green grounding conductors are mixed on the same bars then you should be working on a main service rated panel coming directly from the utility company's meter base where you meter is.

Now as for not having any holes left on your neutral or grounding bar, you may place as many bare or green grounding conductors in one hole on the neutral or grounding bar as you can stuff into those holes on that bar. YOU MUST install only one white wire per hole on the neutral bar. Sounds like you should move a few of your bare wires into the same hole sharing two or three bare or green wires in the same hole on the bar. Then you will have a few holes to install the white wires individually in each hole as required by the NEC.

Hope this helps


October 24th, 2002, 10:28 AM
That answered my question perfectly. I am bookmarking this site because it is so helpfull.

Thanks Again!!!

October 24th, 2002, 04:58 PM
Good Luck with your project.