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Monday, October 24, 2016
Question:
In the course of my inspections I often run into installations where a galvanized rigid steel coupling has been used to transition from an EMT connector to a LFMC (sealtite) connector. I have also observed a galvanized rigid steel coupling being threaded into an offset nipple. I believe that this is a violation and I reference 110.3(B). Although it is a stretch I also mention 344.42(B) as the threads on many fittings, such as offset nipples, include no taper, thus making the threads "running". I am curious about your thoughts on this. Please include code references,
Frederick Mertz
A
Answer:
Hey Frederick thanks for your question. I agree with you and wish I had a dollar for every installation that violates this concept.
The following is part of the guide information for CONDUIT FITTINGS (DWTT) at:
http://productspec.ul.com/document.php?id=DWTT.GuideInfo
All male threaded fittings and nipples have only been investigated for use with locknuts.
Fittings with internal female threads (e.g., hubs, conduit bodies, couplings) have only been investigated for use with threaded rigid conduit.
The 110.3(B) reference you suggested is correct. Consider submitting a Public Input for the 2020 NEC to add wording to make this a clear rule
.