LVPCB Ratings???

[Mike01]

When looking at LVPCB and kA ratings for each[ANSI], manufacturers liste multiple voltage classes and kA ratings for each. For example I was looking at some product literature for Schneider Electric but find this in the other manufacturers as well. Each list three voltage classes 245Vac, 508Vac & 635Vac. So when applying these breakers at what voltage class do you base the kA ratings on ? For example on a 480Y/277V system would one use the 508 or 635Vac kA ratings??? If you assume +/-10% this exceeds the 508Vac?

 

[jim dungar]

For 480V nominal service, you would use ANSI style equipment rated for 508V.

You do not need to consider +/- tolerances, when dealing with the NEC nominal voltage ratings.

 

[templdl]

When looking at LVPCB and kA ratings for each[ANSI], manufacturers liste multiple voltage classes and kA ratings for each. For example I was looking at some product literature for Schneider Electric but find this in the other manufacturers as well. Each list three voltage classes 245Vac, 508Vac & 635Vac. So when applying these breakers at what voltage class do you base the kA ratings on ? For example on a 480Y/277V system would one use the 508 or 635Vac kA ratings??? If you assume +/-10% this exceeds the 508Vac?

Think of interrupting power. That breaker must clear a fault in a very small space and live to tell about it. And what is power? Voltage x current. As voltage increases the ka interupting capacity must go down. Make sense?