Main breaker loading

[kenaslan]

We have an issue here at our office I am hoping can be answered here.

What is the max loading a Main Service Disconect may be loaded to, 80% or Full Load Amps? In this case a Main 600 Amp Service DIsconect with a 511 Amp total connected load and 475 Amps demand load. I say 80% or 480 Amps max, and another engineer here says OK to full load of 600 Amps.

 

[iwire]

A standard over current device is allowed to be loaded 100% non-continuous and 80% continuous.

 

[kenaslan]

Now the question becomes is the NEC calcuated load with demand factors applied...523 Amps...with the new loads installed okay? I say no. The other engineer says yes.

 

[iwire]

Your calculations already include 125% for continuous load.

If the new total calculated load is any amount under 600 amps your good to go.

 

[infinity]

Bob has given you the key factor. The continuous loads are already in the load calculation. You can use 100% of the calculated load to size the service.