I am installing (4) 200 amp meter pak with (4) Tenant breakers, 1 phase 120/240 volt on a commercial bldg. According to local regulations if the load center is more than 6 Ft. from service panel you shall install a (4) feeder conductors with seperate neutral and grounding bus bars. I have sized the conductors at 3/0 copper (90deg C) 225 amp. 2 (3/0) ungrounded conductors, 1 (3/0) grounded conductor. Where in the code does it state what size the grouding conductor can be reduced.
4 conductor feeder
- Thread starter gmartin
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- Massachusetts
Table 250.122 will tell you what size EGC.
3/0 is to small for a 225 amp feeder, your limited to the 75 C rating.
You will need 4/0 copper.
3/0 is to small for a 225 amp feeder, your limited to the 75 C rating.
You will need 4/0 copper.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I think that he's saying that at 90 degrees the #3/0 is good for 225 amps although he cannot use that rating. Since his meter packs are only good for 200 amps I would assume that his OCPD is more likely 200 amps rather than 225 amps therefore the #3/0 are OK.
- Location
- Illinois
- Occupation
- retired electrician
gmartin,
Don
No, that would be Table 250.66.
Don
- Location
- New Jersey
- Occupation
- Journeyman Electrician
gmartin said:
A ground rod doesn't require a conductor to be larger than #6 Cu.
250.66 is the table used for sizing a the ground at the point of entrance service and this is what you run to either the water service or building steel. you size this ground it based on table 250.66 which lists 3/0 ungrounded cu would take a #4 to the water service. that said, if you are wiring a panel that isn't point of entrance (meaning it is fed from a disconnect switch or from a distribution panel-then you use 250.122which sizes the ground per the size of the line side ocpd (this of coarse, would not go to the water service)
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