?
Friday, February 3, 2017
Question:
Charlie, Concerning a 480/277 volt service that has no Neutral Load and according to code the Grounded Conductor needs to be brought to the service equipment per 250.24 (C) , can you address that the Grounded Conductor could be just the Metal Conduit Raceway from the Pad-Mount Service Transformer to the first Service Disconnect and DOSE NOT have to be a wire conductor ? In the definition they define a Grounded Conductor as "A System or Circuit Conductor” Would “A System” be the “Metal Conduit Raceway” bonded at the transformer equipment and X0 and bonded also at the first disconnect and Neutral bar which is bonded to the disconnect frame. I could not find any reference in the code on “A System” or what would be a listed system as defined in the definition. I believe you address this in another older post but I couldn’t find the post and the reference to “a system” was not definable in the code. Referencing 250.24 (C) "Grounded Conductor Brought to Service Equipment" and the definition in Article 100 "Grounded Conductor".
Joe Merecede
A
Answer:
Hi Joe thanks for your question. Various metal raceways are allowed to be used as equipment grounding conductors as stated in 250.118. But metal raceways are not allowed to be used as grounded conductors. Service grounded neutral conductors that are not used for carrying normal load current must still be sized using Table 250.102(C)1) as stated in 250.24(C)(1).