I had a building department comment on this and the code does not address it in black & white. A 1200A main disconnect feeds a wireway with a #3/0 equipment ground. The wireway has 3 400A tenant meters and disconnects on it. What is the size of the equipment ground from the wireway tap to the line side of the 400A disconnect. NEC 250-122 does not address this other than to say it shall not be required to be larger than the line conductor. Clearly a #3/0 equipment ground is oversized from the wireway tap to the disconnect's line side, but how can I prove it? Thanks, Milton
Equipment Ground Size From Wireway Tap to Line Side of D
- Thread starter milton
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Re: Equipment Ground Size From Wireway Tap to Line Side of D
The EGC from the wireway to the line side of the 400 amp disconnect has to be capable of operating the 1200 OCPD, Table 250.122 shows 3/0 for a 1200 amp OCPD.
Look at the words in Table 250.122
[ August 21, 2003, 10:25 AM: Message edited by: iwire ]
The EGC from the wireway to the line side of the 400 amp disconnect has to be capable of operating the 1200 OCPD, Table 250.122 shows 3/0 for a 1200 amp OCPD.
Look at the words in Table 250.122
Once you get past the 400 amp fuses you can base your EGC on 400 amps.
[ August 21, 2003, 10:25 AM: Message edited by: iwire ]
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