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Paul
Paul, Electrician
Category: Electrical
Satisfied Customers: 805
Experience:  23 yrs as an electrician, self employed contractor, municipal inspector
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what size wire for a 250 amp load, 480 volt 3 phase a/c

Resolved Question:

what size wire for a 250 amp load, 480 volt 3 phase a/c
Submitted: 7 years ago.
Category: Electrical
Expert:  Paul replied 7 years ago.

Hi

 

What size breaker are using on this circuit?

 

I assume you are using copper wire in metal conduit.

Customer: replied 7 years ago.
300 AMP BREAKER, FUSE AT 400 AMP DISC BY 250 FUSES
Expert:  Paul replied 7 years ago.

The load is 250A and you are using 250A fuses? Or is the actual load less. This makes a difference on the size wire you can use. It might save you some money.

Customer: replied 7 years ago.
TOTAL LOAD THEY TELL ME IS 250 MAX COULD BE LESS AT TIMES AS THERE ARE 3 MOTORS FOR PART CLEANEING IN THE UNITS THAT ARE STEAM FOR CLEANING
Expert:  Paul replied 7 years ago.

 

Ok then you have to size for the max amperage.

 

For this install you need to use 250mcm copper wire with THHN insulation. You will need to use a #4 copper ground wire.

 

If you need more help please ask here.

 

Paul

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