I noticed that when i looked at the stander main in a panel board OCPD that it was a 225amp. So i us the 225 amp for my sec. Conductor. Thanks. Also, for my info, I do not need to multply the sec. amps by125% right?
I noticed that when i looked at the stander main in a panel board OCPD that it was a 225amp. So i us the 225 amp for my sec. Conductor. Thanks. Also, for my info, I do not need to multply the sec. amps by125% right?
The code says the secondary cannot be greater than 125%, but it does not have to be.
For what it is worth: in this area the most common arrangement has been a 90A primary breaker feeding the 75kVA transformer with a 200A secondary breaker/panel. 30 years ago is was expensive to buy a 480V panel with a branch breaker larger than 100A (of course that does not explain using a 90A one) and the normal residential main was 200A so I think that is what they thought of for 120V circuits. I have noticed some designers using 125A primary and 225A secondary breakers now that they are less expensive especially with the newer EE transformers.