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Code question here. I do a lot of electrical and like to follow code exactly. I have done pretty much everything but hook up lines to main box. Taking a stab at it this time.

First I see that I have circuit breakers in middle with hot going into them and then on each side the neutrals and grounds are connected to a row of screws (on each side). Does it matter what screws I put my ground and neutral in? It looks random right now almost. Also if I flip the main power breaker does that mean I can't get shocked when attaching new breaker?

And then last question - I only have one entry hole left for the breaker box on top. Well I need to put a few more lines in. It is in a basement so everything is coming from the top. What is the code for going around the bottom to enter in a hole there? Not sure I can run the wire behind the box - so can I just wrap the wire around box? Really want this done right. What do you suggest?

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Not sure why gregmac changed the question. The panel has had the neutrals/grounds mixed on each side before I bought my house 15 years ago. Fine if you want to answer the neutral/ground question but I would like the questions in my post answered. –  Tom Apr 17 '13 at 2:58
    
This answer might be helpful. –  Tester101 Apr 17 '13 at 12:31
    
@Tom, on this site we like the title to be int he form of a question. If you have questions about it bring it up in chat or on meta. –  auujay Apr 17 '13 at 18:49
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2 Answers 2

up vote 2 down vote accepted

In the main panel, ground and neutral are connected, so you're free to attach to whichever bar is most convenient. There are two bars because if it was used as a subpanel ground and neutral would have to be kept separated.

The main breaker will cut power to the bus bars and breakers, but the lugs and feeder cables near the top of the panel will still be hot. Shouldn't be too hard to avoid those since the top slots are most likely full anyway and you'll be coming up from the bottom, just pay attention.

I'm not sure what code requires for routing, but it's probably best to drop the wire down in the neighboring cavity and cross through the stud at least 6-12" below the panel before coming back up to keep things nice and tidy. Or for a surface-mounted panel just route the cable neatly and anchor with cable staples:

surface-mounted panel

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OK. I will add on a bit. I have a bar on the left with screws securing both the neutrals and grounds for all breakers on the left. The bar on the right is servicing both grounds and neutrals for the right breakers. And under the box there is no studwork. It is attached to concrete wall. Do I have to frame around it now? –  Tom Apr 17 '13 at 2:13
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@Tom No, you don't have to frame as far as I know; I was just assuming it already was framed. The cables will have to be secured somehow, so you'll probably want to add some plywood (like in the photo) if there isn't some up already. A photo of your panel and the surrounding wall would help people offer more detailed suggestions. –  Brad Mace Apr 17 '13 at 6:04
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Important Code Sections: Assuming NM cable is being used, 334.30 says the cable must be supported and secured within 300 mm (12 in.) of the box and every 1.4 m (4 1/2 ft.). 110.12 Mechanical Execution of Work. Electrical equipment shall be installed in a neat and workmanlike manner. –  Tester101 Apr 17 '13 at 11:30
    
My main panel is on a bare concrete wall - window to the right of it and it is actually against a wall to the left. However there is no framing or plywood behind it. What do you think is the best/easiest way to add something to secure the wires that will wrap under? Everything will be coming from the top originally. –  Tom Apr 17 '13 at 16:02
    
The inspector for the work I did was a stickler for having the cables secured like @Tester101 says. Both at the breaker box and every other box. –  Craig Apr 18 '13 at 13:57
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Let's take this one question at a time.

Does it matter what screws I put my ground and neutral in?

This answer, and this answer provide quite a bit of information, so I'll simply summarize for your specific situation.

As long as this is a Main service entrance, you can connect grounding (ground) and grounded (neutral) conductors to either bus bar. As long as:

  • The grounded (neutral) bus bar is properly bonded.
  • Only one grounded (neutral) conductor can be under a screw terminal.
  • Multiple grounding (ground) conductors can be under a screw terminal, if the terminal is rated for multiple conductors (check manufacturer documentation).

If I flip the main power breaker does that mean I can't get shocked when attaching new breaker?

Flipping the main breaker deenergizes both ungrounded (hot) bus bars, but does not deenergize the main lugs or the ungrounded (hot) feeders. Even with the main breaker off, there is still a risk of shock. If you're not comfortable with this, please seek the assistance of a local licensed Electrician.

I only have one entry hole left for the breaker box on top. Well I need to put a few more lines in. It is in a basement so everything is coming from the top. What is the code for going around the bottom to enter in a hole there? Not sure I can run the wire behind the box - so can I just wrap the wire around box? Really want this done right. What do you suggest?

There are way too many applicable rules to cover them all here, so I'll focus on the one that I think might be most useful to you.

National Electrical Code 2008

ARTICLE 110 Requirements for Electrical Installations

110.3 Examination, Identification, Installation, and Use of Equipment.
(B) Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.

What this means, is that if you can figure out who made the cable clamps at the top of the panel, and can locate the datasheet on these clamps. You may discover that the clamps are actually approved to accept multiple cables. If this is the case, you can simply use the existing clamps to secure both the new and existing cables. If you can't find the data, you could always purchase new clamps that are known to accept multiple cables. Replace the old clamps with the new clamps, and use them to secure both the new and existing cables. If you're working with nonmetallic sheathed cable, you should be able to locate clamps that accept 2 cables. So rather than running extra cable all over the place, I'd explore this avenue first.

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