N3R Junction Box mounted in the snow?

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mpcarnahan

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An electrician I hired mounted a N3R junction box (8x8x6) at ground level on the exterior of a building. He was moutning an exterior disconnect and has two conduits penetrating the bldg beneath it. Why he just didnt put LB's on them and take them up to the disconnect, i dont know. BUt he has both conduits entering this N3R box then one conduit going to the disconnect.
Isn't there some NEC code that says the box must be 'suitable' for its environment? or specific to a N3R box cannot be mounted at grade??
 
The box needs to listed for wet locations and just above grade. The possibility of being buried in snow is not really relevant.
 
jim dungar said:
How about 312.2 and 314.15(A)?
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Nothing in 312 applies to this box.

I only have the 2008 in front of me and I don't see a 314.15(A) but I suspect this is the equivalent section

314.15 Damp or Wet Locations. In damp or wet loca-tions, boxes, conduit bodies, and fittings shall be placed or equipped so as to prevent moisture from entering or accumulating within the box, conduit body, or fitting. Boxes, conduit bodies, and fittings installed in wet locations shall be listed for use in wet locations.
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A 3R box is equipped to prevent the accumulation of moisture. It has drain holes.
 
iwire said:
A 3R box is equipped to prevent the accumulation of moisture. It has drain holes.
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The code specifically says entering as well as accumulating.

If water backups up and enters through one of the drainage holes, then the NEC does have something to say about it.
 
jim dungar said:
The code specifically says entering as well as accumulating.

If water backups up and enters through one of the drainage holes, then the NEC does have something to say about it.
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The box itself cannot prevent water from entering via connected raceways. I suspect that the 3R rating says something about the sources of water that the enclosure is supposed to resist, but I do not have a copy to refer to.
The NEC certainly says that you are responsible for the appropriate placement of the box too.
Maybe there should be a check valve in the drain hole, making it a self-bailing box. :)
 
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GoldDigger said:
The box itself cannot prevent water from entering via connected raceways. I suspect that the 3R rating says something about the sources of water that the enclosure is supposed to resist, ...
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Water is allowed to enter a Type 3R enclosure (it is weather resistant not weather tight) as long as it is below the energized parts and does not accumulate (flows in and then right out).

I just reviewed the installation of a 1200A breaker that 'got wet'. The enclosure and conduits had 4-5" of wet snow piled on them. From the pictures I saw, there were no sealing locknuts, or equivalent, even though the conduits entered at the top of the right hand side. My guess is the damming of the melting snow allowed it to flow, via the threads of the GRC, into the enclosure. It then followed along the conductors and into the top of the breaker.
 
Are we talking about a box or an enclosure containing live parts? I don't see how the requirements are the same.
 
infinity said:
Are we talking about a box or an enclosure containing live parts? I don't see how the requirements are the same.
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There are similar 'entering and accumulating' restrictions in both 312, which also includes a live part issue, and 314, which does not.
 
jim dungar said:
There are similar 'entering and accumulating' restrictions in both 312, which also includes a live part issue, and 314, which does not.
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OK, I thought the original question was about a box not an enclosure which has slightly different rules. For example an enclosure containing live parts, like a meter enclosure, can have standard squeeze connector below the live parts but a box cannot. Does a 3R box have drain holes?
 
mpcarnahan said:
An electrician I hired mounted a N3R junction box (8x8x6) at ground level on the exterior of a building. He was moutning an exterior disconnect and has two conduits penetrating the bldg beneath it. Why he just didnt put LB's on them and take them up to the disconnect, i dont know. BUt he has both conduits entering this N3R box then one conduit going to the disconnect.
Isn't there some NEC code that says the box must be 'suitable' for its environment? or specific to a N3R box cannot be mounted at grade??
Click to expand...
"Suitable for the environment" may possibly mean it needs some corrosion resistance if mounted so close to the ground. Same would go for the raceways entering it.

Also consider conductor sizes and whether or not those conductors would be acceptable for typical conduit bodies if they would have been used. (Think max conductor size the conduit body is designed for). You did not mention raceway sizes or conductor sizes so this is only speculation.
 
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