NEC Regulations re: Relationship between Cabling and Enclosure Size?

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JusticeSmith

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Location
Metro Detroit Michigan
Having no luck finding information regulating the enclosure(think cabinet) sizes allowable/required for x amount of cable, either designated by current carrying capacity or cable length. I've seen Article 300+ on raceways and enclosures and the couple in 700+ about raceways but am not finding anything that denotes a minimum or maximum enclosure allowance based on the cabling in, coming into, or going out of the enclosure. Do you guys know of anything I might have looked over? Thanks.
 
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petersonra

Senior Member
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Northern illinois
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engineer
JusticeSmith said:
Having no luck finding information regulating the enclosure(think cabinet) sizes allowable/required for x amount of cable, either designated by current carrying capacity or cable length. I've seen Article 300+ on raceways and enclosures and the couple in 700+ about raceways but am not finding anything that denotes a minimum or maximum enclosure allowance based on the cabling in, coming into, or going out of the enclosure. Do you guys know of anything I might have looked over? Thanks.
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I don't believe there are any.

IIRC, there are some requirements about sizes of boxes based on the physical size of conductors, but not ampacity or length. There are also some rules about the incoming and outgoing raceway sizes.
 
Smart $

Smart $

Esteemed Member
Location
Ohio
Welcome. :thumbsup:

I'd like to know how you can view 314.16 and 314.28 as not requiring a minimum size enclosure for cabling?

FWIW, I agree the wording of 314.28 is lacking a bit in technical precision, but I believe the intent to mean both raceway and cable based on entry size.
 
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petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Smart $ said:
Welcome. :thumbsup:

I'd like to know how you can view 314.16 and 314.28 as not requiring a minimum size enclosure for cabling?

FWIW, I agree the wording of 314.28 is lacking a bit in technical precision, but I believe the intent to mean both raceway and cable based on entry size.
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presumably you are responding to my response that there are no requirements to size boxes according to either cable length or cable ampacity, which is what the OP specifically asked about.

I then mentioned that there are enclosure size requirements for both conductor size and raceway size.

Do you actually read what people write in their posts and responses to them? sometimes i wonder.
 
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JusticeSmith

Member
Location
Metro Detroit Michigan
Thanks for the quick responses as well as the welcome.

Unfortunately, I did see those tables but they only cover sizes between 6-18 AWG while the box I have in mind(that's housing a xfm), is running pretty much all bigger than 4 AWG lines. Still looking, but the majority of the confusion and subsequent response seems to be about junction and pull boxes instead of larger enclosures with bigger things. Closest thing I saw to a relevant regulation was 312.8 that limited the total of all conductors at any cross section to a percentage of the cross sectional area of that space based on what was included in the lines(conductors, splices, taps). But again, it was for switches or overcurrent devices.

Hope to not be too much of a nuisance, causing a lot of --->:slaphead:

Y'all have a great day.
 
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