I´m looking for a three pole 120/240 rated m.c.c.b ( plug-in or cable-in/cable-out type) UL-489 certified in order to be used in a three phase 208Y/120 volts power system as main protection or feeder.

I´ve seen some products manufactured by Westinghouse/cutler-hammer but rated 240 (called "quick-lag").

Would you please inform me if you know any reference and manufacturer?

JCM,
We use these(Quick-Lag) breakers in some types of Gael switchboards over here in NZ.
Just can't remember who makes them off-hand,
but I can find out for you at work tommorrow!.
These are rated 400/230 and I don't think that they are UL listed either.
BTW, welcome to ECN!!.

Hello Juan, and welcome to ECN.

As I'm in the United Kingdom, I'm not sure of the following, but these are my thoughts:

As the 120/240V system is a 3-wire single-phase service, does anyone actually manufacture a 3-pole breaker so rated?

I'm not sure what rating breakers would be used normally on an American 120/208 service, but I don't see any reason why a 3-pole unit rated for a plain 240V shouldn't be employed.

Could one of our NEC/rating experts in the States please comment?

I know you know this Paul, but... If you have three transformers in delta configuration and ground at the center tap of one of them you get a 120/(208)/240V three phase system...

Thank you for your comments. However let me bring you additional information:The three-phase, four-wire power system I´m speaking is neither the " center-tap grounded delta" nor the " center-tap grounded open delta" but the " grounded Wye" as showed in the following address: http://home.att.net/~benmiller/elecsys.htm

As you realize the phase to ground voltage is 120 volts, not 208 volts.

Would you please bring me your additional concept after having clarified this point?

JCM,
In this particular case, I don't think that voltage comes into it.
As long as the voltage of the unit is above the voltage of the system in use.
3 pole breakers are generally supposed to trip if one of the poles break.
It shouldn't really matter what sort of system that this is done under!.

For a normal type of thermal/magnetic circuit breaker, the voltage rating is the maximum voltage that may be applied, either between phases or from phase to ground.

A 3-pole breaker rated at a straight 240V should therefore be suitable for use on a 208Y/120V system.

A GFI or AFCI would be a different matter, as the electronics rely on the supply being a certain level to operate properly.

I'm surprised none of our friends from the States have responded.

The description of UL 489

This seems like an ordinary molded case circuit breaker. All of the manufacturs must carry them. Square D, Cutler Hammer, Siemens and others.