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electrifier
electrifier, Master Electrician
Category: Electrical
Satisfied Customers: 1633
Experience:  Electrical contractor and electrical inspector for over 24 years with phone and networking expertise
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208 VOLT PRIMARY FEEDING 112 KVA TRANSFORMER 480 VOLT SECONDARY

Customer Question

208 VOLT PRIMARY FEEDING 112 KVA TRANSFORMER 480 VOLT SECONDARY FEEDER SIZES ON BOTH SIDES?
Submitted: 5 years ago.
Category: Electrical
Expert:  electrifier replied 5 years ago.

electrifier :

Is this 3 phase?

Customer:

Yes

Customer:

Any help? Looking for over current sizing on both sides of transformer

electrifier :

112000 / 208X1.732 = 310.9 amps primary 112000 / 480X1.732=134.7 amps secondary

electrifier :

Will you be running THHN in conduit?

Customer:

Yes

electrifier :

350 kcmil will give you 310 amps capacity and 1/0 will give you 150 amps. These are copper conductors

electrifier :

#1 will give you 130 amps capacity

electrifier :

If you protect the transformer at 300 amps on the primary you will be fine on the secondary with protection afforded at 130 amps. There are not 130 amp breakers so a 150 amp breaker will be fine on the secondary. The primary will actually protect the whole installation.

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