Main Circuit Breaker Ampacity

[SMB]

This is an easy one that I can't seem to remember. What formula do you use to determine the MCB ampacity of a panelboard? Is it 100% of non-continuous loads + 1.25% of continuous?

Thanks

 

[jbt260]

This is an easy one that I can't seem to remember. What formula do you use to determine the MCB ampacity of a panelboard? Is it 100% of non-continuous loads + 1.25% of continuous?

You are correct, except it's 125% of continuous. Don't forget to consider non-simultaneous loads and demand factors.

 

[raider1]

Is the overcurrent protection device providing protection for just the panelboard?

Take a look at 408.36 for overcurrent protection requirements for panelboards.

Also take a look at 215.3 for overcurrent protection for feeders.

Chris

 

[bob]

This is an easy one that I can't seem to remember. What formula do you use to determine the MCB ampacity of a panelboard? Is it 100% of non-continuous loads + 1.25% of continuous?

Thanks

The max MCB is the rating of the panel board.