Interrupting Current

[comjos]

How do I calculate interrupting current for a circuit breaker? Can I use a 277V breaker for a 120V system?

 

[jim dungar]

Re: Interrupting Current

You, can not calculate interrupting current for a molded case circuit breaker (MCCB). You need to get this information from the manufacturer.

Yes you can apply a 277V MCCB at lower voltage.

 

[comjos]

Re: Interrupting Current

Thanks for the reply.

 

[tx2step]

Re: Interrupting Current

Are you trying to:

(a) determine the AIC rating of a particular circuit breaker, or

(b) determine the amount of fault current that is available so that you can select the appropriate CB AIC rating?

Determining the rating of a CB is easy -- if it's not on the CB then look it up in the manuf. literature or just ask them.

If you're trying to calculate the available fault current, it can get complicated. There are quite a few variables that you'll need to know. If that's what you're trying to do, then more info is needed.

Edited to add: see related thread at http://www.mikeholt.com/codeforum/ultimatebb.php?ubb=get_topic;f=3;t=001982

[ August 09, 2005, 06:58 PM: Message edited by: tx2step ]

 

[templdl]

Re: Interrupting Current

Also, look for a higher KAIC rating at lower voltages andlower KAIC rating at higher voltages on a given breaker which should be clearly labeled on the breaker nameplate.

 

[danilo]

Re: Interrupting Current

it depends on what breaker are you using,is it MCCB or LVPCB,KAIC requirements also depend on your electrical load.what breaker size are you referring at?