3200 amp service

[zatzot]

What is the smallest size grounded conductor I can run for a 3200 amp 480 volt 3 phase service?
I will be running 500 mcm phase conductors.

 

[iwire]

Re: 3200 amp service

Need more info if you are talking about the grounded conductor.

But if you are talking about the grounding electrode conductor you must be well over 1100kcmil total service conductor size so 3/0 copper 250 aluminum will be the minumum size grounding electrode conductor.

 

[bennie]

Re: 3200 amp service

"Ing" and "ed" no confusion?

 

[charlie b]

Re: 3200 amp service

Zatzot: The ?-ed? word is commonly called the ?neutral.? But a 480V system does not use a neutral. So are you asking about the neutral and are you dealing with a 480/277V service?

p.s. I deleted the duplicate posting from ?Electrical Calculations/Engineering.?

 

[kevin]

Re: 3200 amp service

See 250.24(B)(1): "This (grounded) conductor (brought to service equipment) shall not be smaller than the required grounding electrode conductor specified in Table 250.66...". For 3200 amps, one would need to install over 1100 kcmil per phase, so the minimum size grounded conductor would be 3/0 AWG.

 

[david]

Re: 3200 amp service

Kevin

I read 250.24(B)(1) A little differently

, the grounded conductor shall not be smaller than 12? percent of the area of the largest service-entrance phase conductor.

The grounded service entrance conductor of a 3-phase, 3-wire delta service shall have an ampacity not less than the ungrounded conductors.

[ May 16, 2003, 11:47 AM: Message edited by: david ]

 

[kevin]

Re: 3200 amp service

David,
OOPS!
You are absolutely correct. I learned long ago that blindness is a disease begins in the eyes.
Mea culpa.