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Old 06-11-2012, 02:29 PM   #1
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Maximum wires in a 2 1/2" nipple


My main service panel is mounted on an exterior wall. I have a 2 1/2" x 10" nipple connected to the back of the panel going through to the interior of a sheetrock wall. I am doing some rewire and adding new circuits. Is there a maximum number of wires allowed in the nipple?

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Old 06-11-2012, 02:56 PM   #2
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Maximum wires in a 2 1/2" nipple


What is on the other side of the nipple?

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Old 06-11-2012, 03:07 PM   #3
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Maximum wires in a 2 1/2" nipple


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What is on the other side of the nipple?
The nipple extends through the exterior brick wall into a sheetrock wall. The wall is open from the inside and wires are being pulled from various points in the house through a ceiling chase.
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Old 06-11-2012, 03:30 PM   #4
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Maximum wires in a 2 1/2" nipple


I am seeing 60% fill and no derating here. No?

Chapter 9, T1, Note(4) Where conduit or tubing nipples having a maximum
length not to exceed 600 mm (24 in.) are installed between
boxes, cabinets, and similar enclosures, the
nipples shall be permitted to be filled to 60 percent of
their total cross-sectional area, and 310.15(B)(3)(a) adjustment
factors need not apply to this condition.

Last edited by Code05; 06-11-2012 at 03:34 PM.
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Old 06-11-2012, 03:44 PM   #5
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Maximum wires in a 2 1/2" nipple


I was concerned about branch circuits being mixed with unfused service conductors.

I agree on the 60%, no derate.
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Old 06-11-2012, 03:48 PM   #6
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Maximum wires in a 2 1/2" nipple


Quote:
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I was concerned about branch circuits being mixed with unfused service conductors.

I agree on the 60%, no derate.
If service conductors are involved, I agree, we have a no go.
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Old 06-11-2012, 03:53 PM   #7
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Maximum wires in a 2 1/2" nipple


Quote:
Originally Posted by Jim Port View Post
I was concerned about branch circuits being mixed with unfused service conductors.

I agree on the 60%, no derate.
How do I know when I am at 60%? I could just measure but is there some thing else to consider?What is the reason for this limitation?
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Old 06-11-2012, 03:56 PM   #8
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Maximum wires in a 2 1/2" nipple


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If service conductors are involved, I agree, we have a no go.
What are service conductors? Conductor supplying main service such as from the power company?

Last edited by elmaur; 06-11-2012 at 04:06 PM.
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Old 06-11-2012, 04:19 PM   #9
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Maximum wires in a 2 1/2" nipple


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What are service conductors? Conductor supplying main service such as from the power company?
Yes. They are unfused, except at the pole/tranformer.
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Old 06-11-2012, 04:22 PM   #10
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Maximum wires in a 2 1/2" nipple


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How do I know when I am at 60%? I could just measure but is there some thing else to consider?What is the reason for this limitation?
Heat and insulation breakdown. Do you need us to explain pipe fill and how to calculate it, it is not hard.
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Old 06-11-2012, 04:23 PM   #11
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Maximum wires in a 2 1/2" nipple


To figure the 60% you would need to compute the area of the conductors to be installed vs 60% of the cross sectional area of the 2" nipple.

These values are computed for you in the Chapter 9 Tables of the NEC.
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Old 06-11-2012, 05:30 PM   #12
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Maximum wires in a 2 1/2" nipple


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Heat and insulation breakdown. Do you need us to explain pipe fill and how to calculate it, it is not hard.
I may not need to calculate. I think I'll use another knockout on the back of the panel and divide the wire pulls between the 2 entry points and probably should be good.
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Old 06-11-2012, 06:24 PM   #13
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Maximum wires in a 2 1/2" nipple


Quote:
Originally Posted by elmaur View Post
I may not need to calculate. I think I'll use another knockout on the back of the panel and divide the wire pulls between the 2 entry points and probably should be good.
You could easily install 264 #12 THHN, THWN conductors in a 2 1/2" nipple, I doubt you'll go over... lol... This was using EMT as your nipple, but regardless... I seriously doubt you will have any issues.

Last edited by stickboy1375; 06-11-2012 at 06:26 PM.
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Old 06-11-2012, 06:29 PM   #14
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Maximum wires in a 2 1/2" nipple


Quote:
Originally Posted by elmaur View Post
My main service panel is mounted on an exterior wall. I have a 2 1/2" x 10" nipple connected to the back of the panel going through to the interior of a sheetrock wall. I am doing some rewire and adding new circuits. Is there a maximum number of wires allowed in the nipple?
By the way, is there a junction box or were you sleeving cables through this nipple?
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Old 06-11-2012, 09:18 PM   #15
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Maximum wires in a 2 1/2" nipple


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By the way, is there a junction box or were you sleeving cables through this nipple?
No junction box. My wire pulls are coming from various areas in the house and through the nipple into the main service panel.

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