One feeder - multiple equipment

[bman03]

I have three pieces of high temp resistive heating equipment, the vendor of this equipment calls for a 1200A (208V 3 phase) connected load, and specs a ~250A steady state load once temperature has been reached.

I was thinking it should be possible to feed all three pieces with a single 1800 AMP feeder. Each piece of equipment has it's own 1200 AMP breaker, and the feeder would have an 1800AMP breaker, with appropriate ampacity wiring for 1800AMPS. In this case, all wiring and equipment is protected in accordance with NEC rules (I believe).

In our case we will never start all three pieces simultaneously, and the 1800 would cover the case of starting one piece while the others are at steady state. The reason for doing so would be purely a cost issue, making 3 separate 1200 AMP runs (~120') will cost more.

Any suggestions on what rules this does or does not violate?

 

[BryanMD]

I have three pieces of high temp resistive heating equipment, the vendor of this equipment calls for a 1200A (208V 3 phase) connected load, and specs a ~250A steady state load once temperature has been reached.

Any suggestions on what rules this does or does not violate?

One (larger) feed and a sub panel with proper OCPD?

 

[mdshunk]

I don't think there's any such thing as a guaranteed "steady state" with heating equipment, and the NEC certainly contains no provisions to reduce the branch circuit or feeder ampacity with this reduced demand in mind for heating loads. The full data plate load is what you need to use.

 

[bob]

I have three pieces of high temp resistive heating equipment, the vendor of this equipment calls for a 1200A (208V 3 phase) connected load, and specs a ~250A steady state load once temperature has been reached.

What are the "starting amps" for each unit? Seems to me the load would be
250 amps x 3 x 1.25 = 938 amps.