primary overcurrent protection

[#4electric]

a trans. has a rated pri. current of 90 amperes at 480v. what is the maximum rateing permitted for primary overcurrent protection if secondary overcurrent protection is ommitted

 

[George Stolz]

This looks like a homework question. We will not do your homework for you, but we will assist you in understanding the NEC.

Where have you looked? What are the key words in the question?

 

[#4electric]

from table 450.3(b) current over 9 amps. 90x125%=112.5. no such breaker size, so next higher one is 125amp.from 240.6.

 

[david luchini]

from table 450.3(b) current over 9 amps. 90x125%=112.5. no such breaker size, so next higher one is 125amp.from 240.6.

That is correct.