Trough in an electric room

[quogueelectric]

Many people use trough as a cure all for piping out equipment in an electric room. There used to be some sort of 30 conductor rule for any xsectional area . How does deration factor into trough as far as cccs and % deration apply when lines and loads are all crossed back and forth in the trough which will hide all evils.

 

[sparkyboys]

i have had more than thirty pipes for ccc in an electrical room, but the troughs were separated per panel destination, 120/208 panel and 277/480. I think there 40-60 conduits per section. passed inspection

 

[sparkyboys]

here is a ref: 376.22 A & B and 310.15 B2

 

[infinity]

310.15(A)(2)Ex. IMO provides some relief from the derating requirements after you exceed 30 CCC's in a cross section of a wireway.

 

[chris kennedy]

310.15(A)(2)Ex. IMO provides some relief from the derating requirements after you exceed 30 CCC's in a cross section of a wireway.

Which exception?

 

[Pierre C Belarge]

I find that the size of troughs and the number of ccc in troughs is an issue at least 50% of the time at inspections.


You mention "lines and loads". Do you mean service conductors and other conductors? or Do you mean line and load, such as feeders and branch circuits?

 

[infinity]

Which exception?

310.15 Ampacities for Conductors Rated 0–2000 Volts.
(A) General.
(1) Tables or Engineering Supervision. Ampacities for conductors shall be permitted to be determined by tables as provided in 310.15(B) or under engineering supervision, as provided in 310.15(C).
FPN No. 1: Ampacities provided by this section do not take voltage drop into consideration. See 210.19(A), FPN No. 4, for branch circuits and 215.2(A), FPN No. 2, for feeders.
FPN No. 2: For the allowable ampacities of Type MTW wire, see Table 13.5.1 in NFPA 79-2007, Electrical Standard for Industrial Machinery.
(2) Selection of Ampacity. Where more than one calculated or tabulated ampacity could apply for a given circuit length, the lowest value shall be used.
Exception: Where two different ampacities apply to adjacent portions of a circuit, the higher ampacity shall be permitted to be used beyond the point of transition, a distance equal to 3.0 m (10 ft) or 10 percent of the circuit length figured at the higher ampacity, whichever is less.

___________

 

[quogueelectric]

I find that the size of troughs and the number of ccc in troughs is an issue at least 50% of the time at inspections.


You mention "lines and loads". Do you mean service conductors and other conductors? or Do you mean line and load, such as feeders and branch circuits?

The foreman on the job has designed a trough system of a 12x12 trough which runs around the room in a big circle with two bridging sections crossing at 1/3 and 2/3rds across the middle.
We have an 800a feeder feeding two 400 a 3 ph discos to two 140 ckt dimmer pannels for 2 theatres.
The feeders in and out of the discos to the dimmer panels and then all of the loads all 2 wire cccs 280 X 2 =560 cccs plus feeders popping in and out.
HELLO!
I am now thinking maybe 2-12"troughs are in order stacked.
I am stil not sure but it is not my job I am just trying to think of the next step without pissing everyone off. Diplomacy is the word of the day.

 

[chris kennedy]

I am stil not sure but it is not my job I am just trying to think of the next step without pissing everyone off. Diplomacy is the word of the day.

When did this start to concern you?:-?:grin:

Just bustin chops, an interesting thread that has had me thinking.

 

[quogueelectric]

When did this start to concern you?:-?:grin:

Just bustin chops, an interesting thread that has had me thinking.

I am a state employee now. Pissing people off is not a good career move yet I need to be helpfull without being overwhelming which is what I have a natural tendancy to do. They tell me I could piss off the pope and believe me I am not even trying. I truthfully am only looking to help however. I lack some people skills.

 

[hurk27]

I have seen many troughs installed like this, and for the most part, most of the CCC's are spread out so there are not as many passing each other in one given area, I could not imagine 560 CCC's in one section of a 12x12 trough passing each other.

 

[Pierre C Belarge]

. I lack some people skills.

Hence the cow. :grin:

 

[quogueelectric]

Hence the cow. :grin:

Et tu Brute! Et tu!!