Clamp wires in Panel Box?

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Old 11-08-05, 04:29 PM
Cyberben3D
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Clamp wires in Panel Box?

Hi all - I had an unlicensed electrician run a new circuit for my hot tub last year... now I'm building a home theater and have been doing my own wiring (I installed my first circuit today!). But I noticed the wire he installed comes into the box with no clamp. It seems like if someone gave it a good yank from the attic nothing would stop it from moving around in there.

I intend on pulling it out and installing a clamp, but I have a couple questions out of curiousity. (it's a square D QO box by the way)

1) Is it up to code to have wires coming into the main panel that are not clamped in any way? The original wiring for the house all comes in through a pipe at the top and it looks so crowded I don't think I could even get one out of there never mind put one in. So the new circuits (including the hot tub) are coming through knock-outs.

2) Is it okay to put nuetral and ground wires under the same screw on the nuetral bus bar (he did that too)?

Also, I seem to be running out of screws on the nuetral bus bar although there are plenty of slots for addl. circuit breakers. Is it up to code to double up nuetral wires under the same screw? (I see that the original wiring has doubled up grounds under the same screw)
 
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Old 11-08-05, 04:50 PM
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Technically, it should be 'clamped', as you call it. But I won't tell. You really think people are going to be yanking on wires?

A lot of times I come across things in my line of work where I have to jury-rig improvise. I have seen old houses with metal boxes up in ceilings with no 'clamps'. If I see tension on a wire at the metal edge, I will tug on it away from the metal edge and try to slip some electrical tape in there to be as a cushion, so the insulation on the wire don't get cut by the metal.

You can double up on wires thru cut outs if you have to. I can't see why not.

You can double up neutral and ground wires IF your panel box does not have buss bars separate for neutral and ground. Regardless, though, I have never heard of problems associated with this. In theory, a home is to be grounded outside with a long metal copper rod hamered deep into the ground. This is what your ground wire buss bar goes to. The neutral buss bar follows the ground neutral wire back to the pole and goes elsewhere.
 
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Old 11-08-05, 04:54 PM
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A cable should be clamped where it enters, unless it is entering through a conduit nipple (in that case, it should be stapled where it exits the conduit.

Neutral wires all should be under their own screws. SOME panels allow for ground wires to be doubled up, but ONLY if they are the same guage (two #12s is ok under one screw, but a #12 & #14 is not OK). You should verify that your panel specs allow this.

If you're neutral bar is getting full, you should be able to buy an additional bar. On that fits your SquareD panel should be easy to find.

I'm assuming since you have neutrals and ground wires on the same bar that this is the main panel. In sub panels, they must have separate bars, with the neutral isolated from the box.
 
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Old 11-08-05, 04:57 PM
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Originally Posted by Bonehead
You can double up neutral and ground wires IF your panel box does not have buss bars separate for neutral and ground.

This is incorrect. They can attach to the same bar because it is the main panel. They cannot, however, be terminated under the same screw.
 
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Old 11-08-05, 05:13 PM
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chirkware---Why not?

It was good thinking you stated about two different size guage wires under the same screw. Many people dont realise that due to the size of the hole that the wire slips into... that the tendency is for the wire to, instead of stacking one over the other, to rather squirt off to the side. And since the one wire will be thicker, the screw will only tighten securely to the thickest guage wire.
 
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Old 11-08-05, 05:31 PM
Cyberben3D
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>Bonehead: Technically, it should be 'clamped', as you call it. But I won't tell. You really think people are going to be yanking on wires?

Hmmm did you install my hot tub circuit?! heheh

I'm installing a dozen recessed lights, pulling a lot of new cable... I spend a lot of time in the attic and I've yanked and / or tripped over a few cables myself. It looks like this guy was just lazy... cheap though!

>chirkware: They can attach to the same bar because it is the main panel. They cannot, however, be terminated under the same screw.

Now I'm curious about terminating wires under the same screw... because that is definitely done in the original wiring. Sometimes several grounds are twisted together and terminated as a bundle under a screw, sometimes it's just a pair.

Thanks for the advice on getting an addl nuetral bus bar for the box.

The one thing that's amazed me the most since starting this project is that the NEC is not available in hypertext online. The only thing I found was a java based page flip version that you can't even search...!?
 
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Old 11-08-05, 05:39 PM
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It is specifically prohibited in the National Electric Code (NEC) for two grounded conductors (ie, neutrals) to share a screw.

408.41 (2005 NEC):

Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for another conductor.


Note: The NEC refers to neutrals as grounded conductors, and ground wires as grounding conductors.
 
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Old 11-08-05, 06:05 PM
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Originally Posted by Cyberben3D
Now I'm curious about terminating wires under the same screw... because that is definitely done in the original wiring. Sometimes several grounds are twisted together and terminated as a bundle under a screw, sometimes it's just a pair.

That doesn't sound right. A pair or perhaps three is probably OK, more than that is probably not. Perhaps one of the code guru's can shed more light. I don't find anything specific in the NEC regarding this (but may have missed it), so I imagine what is allowed is determined by the restrictions of the panelboard specs themselves.

I just looked at my Siemens sub panel I recently added. It specifies that 2or 3 #14 wires can share a screw on the ground bar, and that 2 #12 or 2 #10 can share a screw. Your Square D panel should have something similar (look at the table for torque settings perhaps).


Originally Posted by Cyberben3D
The one thing that's amazed me the most since starting this project is that the NEC is not available in hypertext online. The only thing I found was a java based page flip version that you can't even search...!?

It is frustrating. I finally purchased a NEC2005 Pocket Guide to Residential Electrical Installations. It is a much less expensive alternative to the full NEC book, and under $30.
 
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Old 11-08-05, 06:06 PM
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Bonehead, after reading this first reply of yours I really feel you should refrain from giving advice in the electrical forum.



Cyberben3D - Was this installation inspected?
The thought of an unlicensed, unqualified person doing a spa wiring install scares me a bit. If he cut such a simple corner as omitting the cable clamp what else did he omit???
Did he know the code at all? Was he versed in the codes involved in wiring a spa?
 
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Old 11-09-05, 03:05 AM
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Rule No. 2:

If you are hiring an electrician, hire one with a license.

 
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Old 11-09-05, 05:21 AM
Cyberben3D
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And Rule No. 1 is?

Thanks chirk for the tip on that book.

Speedy Petey - I'm going to double check the entire spa run now that you mention it. I have a pretty good book from Creative Homeowners called Home Wiring and it has a chapter on Spa's.
 
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Old 11-09-05, 07:59 AM
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I have to agree about the spa, this is not a good place for experimenting and wondering if it is done right. I dont think a licence is the ultimate answer but no clamps should make this whole install suspect. I have seen where all is fine for a while but over the years somehow that wire has a way of finding sharp edges. I see the handyman installs more than once with wires doubled, ground and whites under the same screw. I was in Home Depot a while back and the HD guy and a customer are trying to figure out what he needs for a hot tub or spa install,, its only a matter of time before we have a big lawsuit, I usually dont say much but pointed out that maybe this wasnt such a good place for a first try at DIY wiring,,, considering that you are sitting in a tub of water with electric connected to it and all,,, they look at me like I just fell out of a tree. HD has some good people, you have to sort thru them to find some qualified advice though, I seen another mis quoting code the other day, he says, they dont really want us quoting code, I said, with good reason. He says, maybe they change this code or that, no, its never been that way and they didnt change it. I see a kid trying to sell speaker wire for smokes, he just cant see why it wouldnt work as the wires on the smokes are tiny anyway. I hand the guy a roll of 14/3 and a 15 A breaker, at least he left the store with the right stuff. Normally I dont try to be too helpfull and MYOB although I did help a nice woman with a dryer install by suggesting that I might be better suited to putting in a new outlet and she may be better suited to cooking a steak dinner, who would figure it could take all weekend to install a new wire and an outlet and change the cord out. hahahahahaha
 
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Old 11-09-05, 11:31 AM
Cyberben3D
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> sberry: I have seen where all is fine for a while but over the years somehow that wire has a way of finding sharp edges

That's the icing on the cake - the way it's coming out of the knockout there is a 2x4 covering half the hole, so the cable is pinched into the corner of the half circle that is left - between wood and sharp sheet metal.

You're right, it's not really about having a license... I don't have one and I don't know the NEC but I know dumb when I see it!

Time to get more ground / nuetral bus bars for my main panel... thanks for the help guys!
 
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Old 11-09-05, 11:57 AM
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Originally Posted by Cyberben3D
Time to get more ground / nuetral bus bars for my main panel... thanks for the help guys!

Use EXTREME care when adding these bars. Turn off the main before getting in there. Even then, stay away from the feeders that bring power into the main. Remember, even with the main off, there's still power present that can kill.
 
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