champion
Member
- Location
- St. Louis Missouri, US
Ref--2002 NEC.
I have 400amp service for a small commercial building that will be cabled with two copper 300kcm cables per phase. 120/208v 3ph.
The GEC conductor per article 250.30 2a will be sized as a 1/0 copper conductor.
This 1/0 will be connected to the neutral bus of the service disconnect and run to a copper water pipe that will be used as the main electrode for this building. This water pipe is located no more than 5 feet.
The bonding jumper between the neutral and the service equipment enclosure at the disconnect (equipment ground bar) which is isolated from the neutral will be bonded with this same 1/0 copper conductor per 250.28D.
-----250.53 D2 indicates that this metal water pipe, which will be the main electrode system for this building, need be supplemented with an additional electrode which will be a 5/8 inch copper 8 foot rod.
250.53E indicates that this connection need not be larger than a no. 6 copper if I so choose.
IS IT ABSOLUTELY NECESSARY TO BOND THE METAL RACEWAY THAT IS USED TO PROTECT THIS NO. 6 WIRE TO THE SUPPLEMENTAL ELECTRODE?
IS SO---I CAN'T REALLY DETERMINE WHERE IN THE CODE BOOK THAT THIS BONDING IS REQUIRED.
I intended to bond this and got caught trying to find out what size by reading the NEC and
started going cross-eyed.
I understand the code to stipulate that the main GEC to the water pipe, if run in a metal raceway, need be bonded at both ends and sized per 250.66 the same as the electrode conductor, but I seem to be having a difficult time trying to interpret whether of not I need to bond the metal raceway for the supplemental electrode.
If so, what size?
Can you help?????
Thank you in advance, and as always, very much appreciated.
I have 400amp service for a small commercial building that will be cabled with two copper 300kcm cables per phase. 120/208v 3ph.
The GEC conductor per article 250.30 2a will be sized as a 1/0 copper conductor.
This 1/0 will be connected to the neutral bus of the service disconnect and run to a copper water pipe that will be used as the main electrode for this building. This water pipe is located no more than 5 feet.
The bonding jumper between the neutral and the service equipment enclosure at the disconnect (equipment ground bar) which is isolated from the neutral will be bonded with this same 1/0 copper conductor per 250.28D.
-----250.53 D2 indicates that this metal water pipe, which will be the main electrode system for this building, need be supplemented with an additional electrode which will be a 5/8 inch copper 8 foot rod.
250.53E indicates that this connection need not be larger than a no. 6 copper if I so choose.
IS IT ABSOLUTELY NECESSARY TO BOND THE METAL RACEWAY THAT IS USED TO PROTECT THIS NO. 6 WIRE TO THE SUPPLEMENTAL ELECTRODE?
IS SO---I CAN'T REALLY DETERMINE WHERE IN THE CODE BOOK THAT THIS BONDING IS REQUIRED.
I intended to bond this and got caught trying to find out what size by reading the NEC and
started going cross-eyed.
I understand the code to stipulate that the main GEC to the water pipe, if run in a metal raceway, need be bonded at both ends and sized per 250.66 the same as the electrode conductor, but I seem to be having a difficult time trying to interpret whether of not I need to bond the metal raceway for the supplemental electrode.
If so, what size?
Can you help?????
Thank you in advance, and as always, very much appreciated.
