Sizing main breaker for Control Panel

[ecuinc]

I have a question on sizing of a main breaker for a control panel. Here is what I have in the panel. Voltage is 480vac, 3phase.

Heater load 549amp
250 HP motor 308amps
7 small motor 67amps
transformer 6.1amps

So I took the largest motor (308amps x 1.25) and got 385 amp plus the sum of the rest of the loads and got 1007.1amps. So I think I need to use a 1200amp breaker. I'm being told I can use a 1000amp. My heating load is non continuous.

Any input would be greatly appreciated.

 

[Nom Deplume]

Does the motor start while the heaters are on?

 

[ecuinc]

The motor will come on first and continue to run, then the heaters will go on/off using zero fire SCR's.

 

[petersonra]

I think you can use a 100% 1000A breaker.

Personally, I would use a 1200A breaker.

 

[JoeStillman]

I think a 1000A and 1200A breaker are the same frame size, aren't they? They are certainly the same $price$ in the Digest.