Secondary protection required?

[Kohlhase]

When installing a panelboard on a secondary I have always put in a main breaker.
I have a customer ask me to add some circuits to a panel and noticed no main breaker feeding a 200A 42 circuit Main Lug panelboard 120/208 from a 75KVA 480x120/208 transformer and there is a 90A breaker on the primary side. I did a little investigating and it is ok if it is 6 circuits or less. With a 42 circuit panelboard though a Main breaker would be required. Am i right?

Exhibit 450.4 and Exhibit 450.5 are what I was using for reference.

 

[raider1]

Take a look at 408.36(B). This section requires that the overcurrent device protecting a panelboard must be located on the secondary side of a transformer.

Chris

 

[Pierre C Belarge]

Also, 240.21(C) is the feeder tap rules for the secondaries of a transformer. For the application you describe, overcurrent protection will be required, in the form of a single means.

 

[templdl]

Transformers with a 1ph3w or 3phw must had a secondary OCPD.
With 1ph2w and 3ph3w toy can privide the transformer with overload protecion on the primary only.
Since the former is usually the case it is of opinion it would depend upion where that secondary protection is located which often is the main breaker of a panel.