Art. 517, bonding of all metal

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Ohms law

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I was recently helping a fellow co-worker in a remodel of a operating room. There was a #4 stranded bonded to every can light, four square box and random steel studs. There was also two isolated power panels that did not have the #4 bonded to the egc terminal buss.

My question is, where is this bonding method mention in the NEC? Is this a engineering design specifically for operating rooms? All lighting and receptacle outlets are piped with EMT and all circuits are on the two different isolated panels with the ground directly bonded to receptacle ground terminal. Hopefully this makes since but I am exhausted trying to understand this article.
 

roger

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I was recently helping a fellow co-worker in a remodel of a operating room. There was a #4 stranded bonded to every can light, four square box and random steel studs. There was also two isolated power panels that did not have the #4 bonded to the egc terminal buss.
Sounds like the OR's are pretty old. The "equipotential" bonding of "all" metallic items in a room was from the days of flammable anesthesia. Today equipotential bonding is still important but not for the same reason and it is not for everything in the room. Today it is for receptacles and fixed equipment that might be in contact with a patient and the IN after 517.11 explains it.

My question is, where is this bonding method mention in the NEC? Is this a engineering design specifically for operating rooms? All lighting and receptacle outlets are piped with EMT and all circuits are on the two different isolated panels with the ground directly bonded to receptacle ground terminal. Hopefully this makes since but I am exhausted trying to understand this article.
See the aforementioned 517.11 IN, 517.13(A)&(B), 517.14, and 517.160(B)


Roger
 

roger

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Thank you for the response. Is there a reason for a #4 copper bonding conductor? Would you size the wire to?
The #4 was probably just the designers spec. When I worked in rooms where we bonded everything we used #10.

Roger
 
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