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Mike G.
Mike G., Master Electrician
Category: Electrical
Satisfied Customers: 7088
Experience:  Proven Professional 46 years Experience
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I have a 208/480 75kva step up transformer. I will be

Customer Question

Hi I have a 208/480 75kva step up transformer. I will be feeding a 100 amp 3-phase panel I need to know what size wire do I need for the primary feed cam u help thanks
Submitted: 11 months ago.
Category: Electrical
Expert:  Mike G. replied 11 months ago.

Hi, I'm Mike G and I'll be assisting you. You need a 1/0 copper conductor on the 480V and #2 copper on the 208V

Customer: replied 11 months ago.
Why do I need a # ***** on the 208 side the machine I will be running is only 55 volts
Customer: replied 11 months ago.
what size breaker for the primary side thanks
Expert:  Mike G. replied 11 months ago.

You said step up, not step down.

Expert:  Mike G. replied 11 months ago.

55A needs a #4 copper.

Expert:  Mike G. replied 11 months ago.

The primary breaker is 125A.

Customer: replied 11 months ago.
Ok so a single phase 125 a breaker to power the transformer
Customer: replied 11 months ago.
Thank you for all the help
Expert:  Mike G. replied 11 months ago.

You're welcome.

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