Tap Rules

[loren]

This is a designed installation. I have a 1200 amp feeder breaker to feed a 1200 amp MCC which has a main breaker in it. The drawings have a jumper on the line side of the MCC Main breaker feeding a 600 amp Mcc right next to it with no main breaker only lugs.

Do the Tap rules apply to feeding an MCC as a device?

Article 430 VIII implies that all MCC's need to have main breakers. I am I understanding this correctly?

I have always designed MCC's to be fed from a breaker or to a breaker.

 

[infinity]

What size conductors are feeding the 600 amp MCC?

 

[iwire]

What size conductors are feeding the 600 amp MCC?

I am not sure that matters.

One of the tap rule requirements must be met.

If it is less than 10' the conductors must be

Not less than the rating of the device supplied by the tap conductors or not less than the rating of the overcurrent-protective device at the termination of the tap conductors.

IMO An MCC is not a device it is equipment that contains multiple devices.

If it is more than 25'

The tap conductors terminate in a single circuit breaker or a single set of fuses that will limit the load to the ampacity of the tap conductors.

 

[hardworkingstiff]

I'm curious as to how the jumpers will be installed. Are there unused lugs on the line side of the 1200-amp MCC main breaker that you will be using for the jumpers? What sized conductors are you using?

How many motors on the 600-amp MCC?

 

[cpal]

loren


I believe 430.94 is in effect as you describe this installation. a main is required unless you can find an applicable exception.


charlie