Maintaining NEMA 4X integrity

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BJBoehm

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I am the electrical inspector on a water treatment plant project. Job specs require NEMA 4X enclosures for outdoor equipment, i.e. dustproof and able to be hosed down. Conduit is GRC PVC coated. Contractor used pvc lock nuts inside and outside for entry to enclosure (which contract allows for NEMA 12 boxes). My point is that the integrity of the 4X enclosure is not being maintain by not using a threaded hub for entry but cannot find this in black and white in NEMA or NEC. I also realize that the issue of unprotected conduit threads is also at issue. Any specific hard references would be appreciated.
Thanks,
Bruce
 
Welcome to the Forum,
Depending on the entry position of the conduit,I think Art 314.15 will support your position requiring a "sealing" means.
If your use of 4X enclosures is for corrosion resistance, then Art 300.6 should support your thoughts that the exposed threads should be treated.
 
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Where it is within my power, i require some kind of screw type hub in all outdoor applications and indoor hose down applications.

I have just seen way too many leaks.

i also don't normally allow top entry in these situations.
 
NFPA79:2007:13.4.1 General Requirements. The means of introduction of cables or ducts with their individual glands, bushings, and so forth into an enclosure shall ensure that the degree of protection is not reduced.

The above is an industrial standard not a legal requirement. Apparently they agree with you that the NEC does not properly cover your requirement.

We also prohibit top entry at our sites.
 
Do the instructions for the enclosures specify how penetrations are to made and sealed? If so that may be some leverage. It's pointless to pay for a NEMA 4X enclosure and then attach conduit in the manner you described.
 
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