Enclosure Size

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peace

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Hello

I need you to help me to know if there is any paragraph in the NEC talking about the relation between enclosure size and number & size of conductors.

I have seen in the site & I found that one small enclosure (35 cm x 25 cm x 10 cm) has two cable (3 wires) size 120 mm2

So can I use any paragraph in the NEC to know the correct size?

Thanks
 
i have read table 314.16(A) but this table didn't talk about circuit breaker enclosure, i think it talk about metal boxes ( Junction boxes)

may be my quas
 
peace said:
i have read table 314.16(A) but this table didn't talk about circuit breaker enclosure, i think it talk about metal boxes ( Junction boxes)

may be my quas
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How about Articles 408 and 409?
What kind of installation do you have?
steve
 
If you are designing an enclosure to hold many different components, the NEC is not the best reference except for 312.6, 312.7, 312.8, 409.10, and 430.10 which primarily address wire bending space.

If you are building a circuit breaker panelboard or switchboard, then you also need to look at 408.56 for exposed (bare metal) parts only.


I suggest you also look at NFPA 79 the Electrical Standard for Industrial Machinery as well as several of the UL standards.
 
hillbilly said:
How about 314.16
They don't teach this in Electrical Engineering School?
steve
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I think it is a common misconception that electrical engineers learn stuff like this in school.

Most electrical engineering programs don't teach the NEC or anything remotely similar to what a engineer doing industrial, residential, or commercial wiring uses. That's right. 4 years of school, and not a single word about the NEC, wire types, conduit types, panelboards, disconnects, or anything remotely similar.

Everything they do teach is geared toward design or theory. Anything technical is out. The engineer is expected to learn that on the job.

And one reason is that most electrical engineering programs are very broad. The same program produce engineers that design cell phones, electronics, semiconductor chips, control systems, airplanes, and computers. Some may even become computer programmers, accountants, business managers or (cough) sales people.
 
breaker enclosure

breaker enclosure

Peace,
check out 312.8 in the 2002 nec. Sorry we here in california are so progressive that we rewrite (copy for the most part) the entire NEC add a few typos and some very minor changes, take a couple of years to adopt it, and call it the California Electrical Code. So October 1, 2005 we adopted the CEC 2004 which is a copy of the NEC 2002. Confused yet?
Anyway, the wireing space around the breakers shall not be filled greater than 40% of the cross sectional area. Or 75% where you have splices.
This section also answers the age old question "Can I splice in or use a panel (cabinet) for a raceway?"
And once you get that 40% fill, good luck finding any room for splices!!!!
 
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