Electrician Talk banner
1 - 5 of 5 Posts

·
Registered
Joined
·
50 Posts
Discussion Starter · #1 ·
Is anyone familiar with a code article stating that you can have no more than 30 current carrying conductors running horizontal in a trough? I cannot find it. We have a 6x6x36" trough above a panel with 3/4" emt's coming in the top, 4-2 1/2" out of the bottom to the two electrical panels. Not crowded, inspector says can't do it. Anyone?
 

·
Registered
Joined
·
326 Posts
There is not a 30 conductor limit.
There is a requirement for derating after 30 conductors.

376.22 Number of Conductors and Ampacity

The number of conductors and their ampacity shall comply with 376.22(A) and (B).

(A) Cross-Sectional Areas of Wireway. The sum of the cross-sectional areas of all contained conductors at any cross section of a wireway shall not exceed 20 percent of the inte-rior cross-sectional area of the wireway.

(B) Adjustment Factors. The adjustment factors in 310.15(B)(3)(a) shall be applied only where the number of current-carrying conductors, including neutral conductors classified as current-carrying under the provisions of 310.15(B)(5), exceeds 30. Conductors for signaling circuits or controller conductors between a motor and its starter and used only for starting duty shall not be considered as current-carrying conductors.
 

·
Registered
Joined
·
3,450 Posts
I use gutter quite a bit, but the trick is trying to stay under 30 ccc's in any one cross section. I try to bring conduits into the gutter over the panels they'll go into if possible, that helps cut down on the wires running back and forth through the gutter.

If all else fails, you may be able to use 310.15(A)2 Exception if you meet the requirements.

I have heard of stacking two gutters on top of each other with chase nipples in between if you know your going to have a lot of ccc's but that's a pretty extreme install. Maybe your inspector would let you get away with a divider to break the wire bundle up?
 

·
Registered
Joined
·
50 Posts
Discussion Starter · #4 ·
Yea, we have to watch derating in conduits here but we've never been called on the troughs above the panel. Going to be a tricky and expensive fix. I do appreciate the input guys! Thank you
 

·
Registered
Joined
·
2,960 Posts
I have heard of stacking two gutters on top of each other with chase nipples in between if you know your going to have a lot of ccc's but that's a pretty extreme install. Maybe your inspector would let you get away with a divider to break the wire bundle up?
We did that on a job once, because there was 4 lighting panels and a large contactor panel and there was a structural steel beam in the middle.. What a PITA!!! Cables came in the back one and panels were nippled to the wireway.. Then any spares, wires that had to go across the beam and wires that we couldn't get into the back on went into the front one.. Hind sight 20/20, I would have rethunk that layout, but I was an apprenti then..
 
1 - 5 of 5 Posts
Top