Help with AIC ratings for this MechE..

[Joethemechanic]

I would imagine using a breaker below it's rated voltage would increase the AIC. Such as a 480 volt breaker on a 208 circuit. Is there any way this increase in AIC can be applicable?

 

[jim dungar]

I would imagine using a breaker below it's rated voltage would increase the AIC. Such as a 480 volt breaker on a 208 circuit. Is there any way this increase in AIC can be applicable?

It is done every day by manufacturers. Take a look at the labels on any industrial breaker (they are usually large enough to read) or look in their catalogs.

 

[petersonra]

Yes, and the old line AB breakers were brand labeled Westinghouse, then by virtue of the buyout, Eaton. It was Eaton that I had the argument with on AIC ratings when I was with an OEM. AB not longer brand labels the Eaton breakers though.

I think they are now made by ABB.

I don't know if UL allows this anymore but it used to be that if you wanted a breaker that could be reverse fed it had to have non-interchangeable trip elements. I never understood why, there seems to be no obvious reason for this, but some MCCB manufacturers would install regular interchangeable trip elements and then put a seal over it and then UL would allow them to market it as a MCCB that could be reverse fed.

I also have been told that some IEC contactors that are labeled with lower ratings for some models in the same frame size are internally identical.

 

[jim dungar]

I don't know if UL allows this anymore but it used to be that if you wanted a breaker that could be reverse fed it had to have non-interchangeable trip elements. I never understood why, there seems to be no obvious reason for this, but some MCCB manufacturers would install regular interchangeable trip elements and then put a seal over it and then UL would allow them to market it as a MCCB that could be reverse fed.

They don't want you exposing live parts when you pull out the trip unit.