CQD: 12/12/2016

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Monday, December 12, 2016

Question:

I am installing 230 volt - 1 phase equipment in a research lab. The equipment comes from the manufacturer with a cord with a NEMA 14-30P plug (4-wire). However, the neutral is not required, per a note on the equipment drawing that says neutral not connected. The 230 volt distribution in the research lab is supplied from a delta secondary transformer, so there is not a neutral available. My question is, can I install NEMA 14-30R receptacles without any connection to the neutral lug on the receptacle without violating the NEC? This receptacle is dedicated to this equipment, i.e. it is not a general purpose receptacle, and could be labeled as "no neutral connected" or something like that. My other option may be to cut the NEMA 14-30P plugs off the equipment and install NEMA 6-30P plugs (3-wire) and NEMA 6-30R receptacles (3-wire). Thanks for your help.

Greg Long

Answer:

Hey Greg thanks for your question. I am not aware of a NEC rule that requires all "poles" of a receptacle to be connected to a conductor or source of power. Marking the receptacle as you suggest is a good idea, maybe even state that it is supplied from a 3 wire delta secondary transformer, no neutral conductor available.

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