For Mission Critical Circuit Breakers, what is the difference in the LAL-MC / LHL-MC versions, and the Powerpact J-W and L-W versions?
Mission Critical Circuit Breakers
The LAL-MC and LHL-MC Mission Critical thermal/magnetic circuit breakers are obsolete. Compared to standard LAL and LHL breakers, these MC versions had a very high instantaneous trip setting. Information on these obsolete Legacy LAL-MC/LHL-MC Mission Critical breakers is still available in our Technical Library at this link. LA/LH Mission Critical Circuit Breakers
Our current style Mission Critical breakers are in the family of Powerpact J and L electronic circuit breakers. These catalog numbers have a “W” appearing just after the breaker amp rating (example: LGL34400WU33X). The characteristic of these J-W and L-W breakers is different than the obsolete LAL-MC and LHL-MC breakers. For example, the Powerpact J-W and L-W Mission Critical breakers do not have a high instantaneous trip setting. They have the same trip curves as standard Powerpact J and L breakers. The difference is that the Powerpact J-W and L-W Mission Critical circuit breakers coordinate much better with downstream smaller breakers such as QO, ED, EG and EJ breakers. Information on the Powerpact J-W and L-W Mission Critical Circuit Breakers can be found in our Technical Library at these links: Powerpact J Mission Critical Circuit Breakers Powerpact L Mission Critical Circuit Breakers
Depending on the situation, there is sometimes still a need for a Mission Critical circuit breaker with a high instantaneous trip setting. It might be possible to achieve that by selecting a higher amp Powerpact L-W Mission Critical circuit breaker, and then field adjust the long-time and instantaneous dials to the desired level. Whether or not that can be done has to be determined on a case-by-case basis.