Jbox and grounding

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  #1  
Old 08-13-04, 02:10 PM
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Jbox and grounding

Hi,

I'm looking for advice on how to wire a few new circuits. I have a combination "panel-meter" that is outside the house. I want to run several new circuits from the panel, new outlets in the basement, a dedicated circuit for the washer, etc. I plan to add 4-6 new circuits now, more later.

As I said the panel is outside. I plan on running PVC conduit from the panel, into the crawl space, about 4 feet. I have a big 12x12x4 Cantex Jbox mounted to the floor joists. I think this is OK; good advise I got from this forum a few months back. Now I need to run Romex from the Jbox to the recpts. I have a few questions:

1) I don't want to splice every wire in this box. Actually, I don't see why I need to splice any wire in this Jbox... Can I just strip back the Romex plastic, and fish the individual THHN into the PVC and to the panel? What about the bare grounds? Can they be run in PVC? They would be outside the house in the PVC, and bare. Is this to code? I can't find anyone that carries Romex with a green insulated ground. Did they stop making this? I'd feel better if the Romex had fully insulted ground wire.

2) I'm a little worried about the type of clamp to use where the Romex enters this Jbox. Can I use a metal clamp here? Does it need to be bonded to the grounds?

Thanks for any advise. I want to make this simple, but safe.

S.

PS. You used to be able to search on a single forum here, but it looks like that is not possible anymore on this site. Makes it hard to see if anyone might have asked similar questions in the past. It would be good if they got that search option back... my 2 cents.
 
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  #2  
Old 08-13-04, 02:24 PM
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Do not strip the NM (until you get inside the panel). Assuming the conduit is large enough, just feed the NM through the conduit. This means the junction box isn't even necessary.
 
  #3  
Old 08-13-04, 04:25 PM
diydon
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No junction box

Remove the box as the previous post implys.. that way this PVC is a "chase" not a conduit run. This means you can simply slide the romex through the PVC chase into the panel.

If you leave the box.. technically this is a "raceway" and NM (romex) is not allowed to be run in it. You would need to splice and use THHN (single conductor stranded).

-don
 
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Old 08-13-04, 05:15 PM
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Thank you both for the very fast reply. Removing the box makes my life easier. But now I have a 40$ plastic oil pan

How many 12/2, 20A circuits can I run in 1.5" or 2" PVC? If it is a chase, not conduit, how are the fill restrictions/calculations done?

Sorry for the endless questions, but how would I secure the Romex at the panel? If it just runs into the open end of the PVC and out at the panel, there is no clamp...


Thanks again,

S.
 
  #5  
Old 08-13-04, 07:00 PM
diydon
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cable ties

I typically wrap a cable tie or two at the entry point of the chase (where the j box was.) Then use another cable tie to attach this to the floor joist or what have you.

This will keep the romexs from sliding either direction.

Nothing additional is required at the panel... simply leave 1/2" or so of sheathing out of the PVC.


-don
 
  #6  
Old 08-14-04, 10:04 AM
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I would not put more than four NM cables in any one conduit. This is not for fill reasons, but for ampacity derating issues. If you have more than four, use multiple conduits with nor more than four in each.
 
  #7  
Old 08-15-04, 11:07 AM
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Hi,

Right now I'm running 4, laundry, washer, frig, and basement. What size conduit can carry 4? The panel only has 1 knock out big enough for 2"... There are 3 or 4 knockouts that look like 1 1/2".

We plan on a kitchen remodel this fall, that could add 4 circuits. Also the house hase no grounds (knob and tube) so I see the need to pull more in the future. (The previous owner put insulation over the KT which I know is not good.)

So, if I need 16-20 circuits in the next year or so, what options do I have other than five conduits?

Thanks again for all the help. I want to plan this right so I don't end up ripping out something I just installed, or looking like a fool when the inspector shows up.

Steve
 
  #8  
Old 08-15-04, 02:09 PM
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1 1/2" would hold 4 NM cables easily...and if your only foreseeing pulling grounds in the future, dont worry about making it any bigger for derating. Derating rules only apply to current carrying conductors, not grounds.

If you mean 16-20 completely new circuits, while you (or whoever) is drilling thru the concrete or whatever, go ahead and drill in enough 1 1/2" to fill all the knockouts you have, and may as well fill the 2" as well, if you even THINK you may EVER need it I would put 'em in now.
 
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