How do you size a service that will have 2 - 800a and 1 - 400a breaker

[Tx elextrician]

We are swapping out 3 Ats and i wanted to set up a temporary panel that can handle the load of all three . There are 2 - 800a and 1 - 100 a Ats. Do i just add them up and size my feeders from the total amperage? Any help would be appreciated. Thanks

 

[publicgood]

You could do that. Sounds expensive. If these are mix of NEC 700/701/702 you can’t. Worse if this is healthcare.

 

[electrofelon]

Generally adding breaker/feeder sizes will result in a much larger than necessary system. Not sure if these loads you are talking about constitute the whole service, but if they do, how about getting demand data from the utility?

 

[kwired]

Just because you have an 800 amp breaker doesn't mean it sees 800 amp of load. On top of that you indicate this is for temporary purposes, I'd be looking even harder at what the actual load will be during the use of this temporary setup.

As mentioned if legally required standby or healthcare those can complicate things easily.

 

[publicgood]

Remember NEC 527 applies for temp installa

 

[electrofelon]

Remember NEC 527 applies for temp installa

Not if its done on a weekend :lol:

 

[publicgood]

Not if its done on a weekend :lol:

You gambler, you