Definition: Bus rating and AIC rating

[zam]

Consider an electrical panel that has a 150 amps Main Circuit Breaker, 225 amps Bus Service Size and 10K Ampere Interrupting Capacity. In layman's terms, what is the definition of Bus size and AIC rating? Thank you for your time.

 

[wbdvt]

Basically the bus rating is the amount of amperage that the bus is designed to safely carry

The AIC rating is applied to breakers and gives the amount of short circuit current that the breaker can safely interrupt.

There is another rating, SCCR, which is applied to panels and relates to the short circuit rating of the panel

 

[kwired]

Basically the bus rating is the amount of amperage that the bus is designed to safely carry

The AIC rating is applied to breakers and gives the amount of short circuit current that the breaker can safely interrupt.

There is another rating, SCCR, which is applied to panels and relates to the short circuit rating of the panel

That is about as short and simple as the answer can get.

The bus doesn't interrupt current, if it does it melted until it opened:happyyes:

SCCR isn't necessarily how much SCC the bus itself can carry, but rather how much magnetic force between separate buses during the fault incident can be tolerated before whatever they are secured to may become compromised.

 

[zam]

Consider an electrical panel that has a 150 amps Main Circuit Breaker, 225 amps Bus Service Size and 10K Ampere Interrupting Capacity. In layman's terms, what is the definition of Bus size and AIC rating? Thank you for your time.

Please correct me if I am wrong. In my above example, is it correct if I say: A 225 amps bus is a metallic strip or bar in the electrical panel that allows maximum 225 amps current to be safely carried through the electrical panel. Thank you.

 

[kwired]

Please correct me if I am wrong. In my above example, is it correct if I say: A 225 amps bus is a metallic strip or bar in the electrical panel that allows maximum 225 amps current to be safely carried through the electrical panel. Thank you.

Yes, think of them as a feeder conductor that has an ampacity of 225 amps.

If they have a 10 kA SCCR, then that means the mounting/bracing of those bars were designed/tested to take the magnetic forces imposed on the bar when 10kA of fault current is flowing, and they should not become "unfixed" during that fault.