312.5 c

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jap

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Why can't the Raceways entering the top of a Surface Mount Enclosure be less than 18" ? Where did this measurement come from and what diffference would it make if it were Less?
Also, Why is this only allowed on Surface Mount Enclosures and not Recessed?
 
Going to take a wild guess...to get to a safe 8' height for physical wire protection...and with main breaker height the NEC uses, 18-24" would be just about right to keep the wires out of harms way while not building up heat in a long pipe. 2ndly, The conduit in the wall would keep heat in and possible damage insulation/wires. Did I get any cigars?
 
jap said:
Why can't the Raceways entering the top of a Surface Mount Enclosure be less than 18" ? Where did this measurement come from and what diffference would it make if it were Less?
Also, Why is this only allowed on Surface Mount Enclosures and not Recessed?
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Great question I have often wondered this myself. I believe the 18" is to keep any sparks etc from exiting the conduit if a short should occur inside the panel. Just a guess. I assume surface because they want the conduit visible for inspection.-- Another guess. I guess crap can also fall into the pipe easily if it is less than 18". Needless to say, I have seen it way to often where a 2"pvc conn is installed in the top of a panel ( both recessed and exposed) with many nm cables installed thru it.
 
I have seen a lot of Panels (Mostly Residential) that have a Spare Stub up to the attic for ease of access in the future that were not sealed off (violation).
Most of the time there are so many romexes crammed in a stubup that there is no good way to seal it off (violation). Also there are so many romexes in the stub that they fail to staple within 12" of the stubup (violation).
There are very few times where I have seen all of the Items of 312.5 c that were met. IMHO They should make it a violation to Stub NM all together and be done with it.
 
chris kennedy said:
Help me out here, I don't see that.
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Look here:

312.5 Cabinets, Cutout Boxes, and Meter Socket Enclosures.
Conductors entering enclosures within the scope of this article shall be protected from abrasion and shall comply with 312.5(A) through (C).
(A) Openings to Be Closed. Openings through which conductors enter shall be adequately closed.
(B) Metal Cabinets, Cutout Boxes, and Meter Socket Enclosures. Where metal enclosures within the scope of this article are installed with messenger-supported wiring, open wiring on insulators, or concealed knob-and-tube wiring, conductors shall enter through insulating bushings or, in dry locations, through flexible tubing extending from the last insulating support and firmly secured to the enclosure.
(C) Cables. Where cable is used, each cable shall be secured to the cabinet, cutout box, or meter socket enclosure.
Exception: Cables with entirely nonmetallic sheaths shall be permitted to enter the top of a surface-mounted enclosure through one or more nonflexible raceways not less than 450 mm (18 in.) and not more than 3.0 m (10 ft) in length, provided all of the following conditions are met:
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chris kennedy said:
Help me out here, I don't see that.
Click to expand...
Does this help old man.
(C) Cables. Where cable is used, each cable shall be secured to the cabinet, cutout box, or meter socket enclosure.
Exception: Cables with entirely nonmetallic sheaths shall be permitted to enter the top of a surface-mounted enclosure through one or more nonflexible raceways not less than 450 mm (18 in.) and not more than 3.0 m (10 ft) in length, provided all of the following conditions are met:
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I see it....

Exception: Cables with entirely nonmetallic sheaths shall be permitted to enter the top of a surface-mounted enclosure through one or more nonflexible raceways not less than 450 mm (18 in.) and not more than 3.0 m (10 ft) in length, provided all of the following conditions are met:
Click to expand...
 
jap said:
Also, Why is this only allowed on Surface Mount Enclosures and not Recessed?
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There is no need to do this in a recessed installation, at least that I can tell.

For a surface installation, it would help esthetically, as well as giving some protection to the romex.
 
jap said:
Also, Why is this only allowed on Surface Mount Enclosures and not Recessed?
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Thats how the proposal was made and accepted. We'd have to go back and find the ROP and ROC for more history.

Why don't you make a proposal for the 14 NEC?
 
I have seen this on several houses where the stub came into the bottom of a recessed panel and wondered how it passed inspection.

Why is out the top any better or safer than one out of the bottom?
 
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