flightline
Senior Member
Just as there are numerous different "protections" that the different NEMA ratings for encosures afford wiring, and as we must choose the right NEMA rating for a piece of equipment we install, where is the code section that dictates, (specifically if possible), how we maintain that rating? That's kinda' cryptic so let me offer a "for instance"
Lets say we have a 200 amp overhead meter socket for installation on the exterior of a building. The meter socket is rated, among other things, NEMA 3R. ( This could also be a disconnect switch, or pullbox for most of this discussion) For top entrance, the manufacturer provides a raised lip/opening and we bolt on the threaded hub. The combination of the raised lip and the threaded conduit connection that the hub affords maintains the NEMA rating. (when properly installed)
But let's say that you must enter the side of the enlosure, whatever it is. If you are using rigid conduit, regular locknuts & bushing, [I believe], won't maintain the NEMA 3R rating. You could use sealing locknuts or conduit hubs. If you use a no-thread connector, or compression thinwall connector, are you required to provide "supplemental" gasketing to maintain the NEMA 3R rating? You buy fittings for liquidtight flexible metallic conduit, and manufacturers sometimes provide a plastic sealing ring between the conduit body and the locknut. You install "Bell" or FS type boxes, and they employ threaded hubs for connection.
What brings me to this question? Well, I had an electrician install some real nice, (and $$$) Square D Heavy Duty 3R disconnects for some A/C condensing units and piped into the side. He hole sawed the conduit entrances with a bit that was off center enough to provide a hole out of round enough that I could see light through, with the "set-screw" no thread connector installed. When I cited the electrician for not maintaining the NEMA rating, and installing an "improper fitting" requiring one that is suitable for use in the environment to which it is exposed, he came back with an attitude telling me to show him "where in the code" this was. I was at a disadvantage and could only cite the workmamlike, closing openings, and other such "generic" code sections.
I wrote to NEMA and UL asking for some direction or an answer, but have never received a response. I didn't want to bother the forum without trying to do my homework first. I hope you can help, and I thank you in advance for your time.
Lets say we have a 200 amp overhead meter socket for installation on the exterior of a building. The meter socket is rated, among other things, NEMA 3R. ( This could also be a disconnect switch, or pullbox for most of this discussion) For top entrance, the manufacturer provides a raised lip/opening and we bolt on the threaded hub. The combination of the raised lip and the threaded conduit connection that the hub affords maintains the NEMA rating. (when properly installed)
But let's say that you must enter the side of the enlosure, whatever it is. If you are using rigid conduit, regular locknuts & bushing, [I believe], won't maintain the NEMA 3R rating. You could use sealing locknuts or conduit hubs. If you use a no-thread connector, or compression thinwall connector, are you required to provide "supplemental" gasketing to maintain the NEMA 3R rating? You buy fittings for liquidtight flexible metallic conduit, and manufacturers sometimes provide a plastic sealing ring between the conduit body and the locknut. You install "Bell" or FS type boxes, and they employ threaded hubs for connection.
What brings me to this question? Well, I had an electrician install some real nice, (and $$$) Square D Heavy Duty 3R disconnects for some A/C condensing units and piped into the side. He hole sawed the conduit entrances with a bit that was off center enough to provide a hole out of round enough that I could see light through, with the "set-screw" no thread connector installed. When I cited the electrician for not maintaining the NEMA rating, and installing an "improper fitting" requiring one that is suitable for use in the environment to which it is exposed, he came back with an attitude telling me to show him "where in the code" this was. I was at a disadvantage and could only cite the workmamlike, closing openings, and other such "generic" code sections.
I wrote to NEMA and UL asking for some direction or an answer, but have never received a response. I didn't want to bother the forum without trying to do my homework first. I hope you can help, and I thank you in advance for your time.
