(2) 4" conduits through class 1 div 1 area

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MidwestJest141

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Electrical Engineer - Power and Controls
Hello I am trying to size a pull box. I have 2 4" inch ARC conduits running through a class 1 div 1 area one of the conduits is spare and one of them has 3 500kcmil feeder wires with #2 ground. I need to size pull/junction boxes for this run through the classified area. With straight pulls considered I think I need a minimum of 32" width pull box. i am struggling with what height the pull box need be for the 2 4" conduits? what kind of spacing is required between conduits in a pull box? Thanks!
 
don_resqcapt19 said:
You are going to need a very expensive pull box.

I would look very hard for a way to eliminate any pull box in a Class I, Division 1 location.
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Yes i would however the client wants to go with the pull-box route. this is a long run. we offered armored cable as an option through the area to avoid need for conduit/fittings etc... they went the conduit and fitting route.

i think i have the details needed for sizing the pull-box properly now. Thanks all.

Next Question. seal offs are required on the boundary of class 1 div 1 area. do these pull boxes require seal offs as well? when i read 501.15(A) (1) - (4) i gather that this pull box does not require seal offs because it does not contain arc producing devices nor does it contain splices taps. if i understand correctly then i am just needing seal offs on the boundary's of the classified area for these two 4" arc conduits.
 
petersonra said:
I don't recall off hand but isn't there a requirement to seal conduits st boxes when the conduit gets above a certain size?
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501.15(A)(1) (2)
"The entry is metric designator 53 (trade size 2) or larger, and the enclosure contains terminals, splices, or taps."

This enclosure does not contain terms, splices, or taps. this is where I exclude my conduits in/out of pull box needing sealing.
I apologize in advance for any possible un-intelligent NEC understandings here. I am pretty new to NEC and design so please bear with me as i am struggling through this :D.
 
MidwestJest141 said:
Yes i would however the client wants to go with the pull-box route. this is a long run. we offered armored cable as an option through the area to avoid need for conduit/fittings etc... they went the conduit and fitting route.

i think i have the details needed for sizing the pull-box properly now. Thanks all.

Next Question. seal offs are required on the boundary of class 1 div 1 area. do these pull boxes require seal offs as well? when i read 501.15(A) (1) - (4) i gather that this pull box does not require seal offs because it does not contain arc producing devices nor does it contain splices taps. if i understand correctly then i am just needing seal offs on the boundary's of the classified area for these two 4" arc conduits.
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Seals are required at the Class I, Division 1 boundaries. The will be required at the enclosure if there are terminations or splices. Even though the enclosure may not require seals, it still has to be an explosionproof enclosure.

Note that standard seals have a fill of 25% and not 40% like the conduit, so you may need oversized seals.

501.15(A)(1) for the enclosure and 501.15(A)(4) for the boundary.
 
MidwestJest141 said:
I apologize in advance for any possible un-intelligent NEC understandings here. I am pretty new to NEC and design so please bear with me as i am struggling through this :D.
Click to expand...
Many of us struggle with hazardous locations. We have some very knowledgeable persons here, ask away
 
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