xguard
Senior Member
- Location
- Baton Rouge, LA
Is a miniature circuit breaker that is listed to UL 489 considered a Molded Case Circuit Breaker as the term is used in 430.109(A)?
MCCB UL 489 vs Miniature UL 489
- Thread starter xguard
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
It is my understanding that miniature circuit breakers are molded case circuit breakers.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
UL489 is the standard for Molded Case Circuit Breakers, so IF they are listed under UL489, then yes.
Might be kind of a moot point however because that code section is just defining a "disconnect" and further down on that list (#7) is "Manual Motor Controller". Most of the non-UL489 versions of those little IEC type MCBs are co-listed as UL1077 "Supplementary Protectors" and UL508 "Manual Motor Controllers" anyway.
Why do you ask? The reason I ask that is that the biggest issue with using those things in motor control circuits is that they have VERY low AIC ratings, often 10kA but I've never seen more than 18kA. In most industrial 480V panels that's way too low to be of any practical use and many many installing contractors get burned by having someone use them in a panel and expect the contractor to "deal with" the low SCCR on the panel, thinking it's something they can take care of. It isn't.
Might be kind of a moot point however because that code section is just defining a "disconnect" and further down on that list (#7) is "Manual Motor Controller". Most of the non-UL489 versions of those little IEC type MCBs are co-listed as UL1077 "Supplementary Protectors" and UL508 "Manual Motor Controllers" anyway.
Why do you ask? The reason I ask that is that the biggest issue with using those things in motor control circuits is that they have VERY low AIC ratings, often 10kA but I've never seen more than 18kA. In most industrial 480V panels that's way too low to be of any practical use and many many installing contractors get burned by having someone use them in a panel and expect the contractor to "deal with" the low SCCR on the panel, thinking it's something they can take care of. It isn't.
Last edited:
xguard
Senior Member
- Location
- Baton Rouge, LA
These are rated 22 kaic. It's an Eaton QBHW.
- Status