I have encountered a 1200A MCCB in a facility with the instantaneous trip elements removed. The breaker is a Westinghouse NB style. My question: is this an NEC violation?
Thank you in advance!
Was this a factory mo dr I fixation? Probably not as the trip unit would have to be removed and the factory sealed remove in order to access and defeat the instantaneous elements. Also, the MB breaker never had a short time delay. A model was available as a molded case switch with a dummy trip unit until the mid '80s or do the it was not allowed as the device could be destroyed should it's withstand be exceeded. As such high mag only trip units were required after that which included the modification suffix 'K". There is no option to remove the instantaneous trip.
But it is interesting the the OP omitted and part or style numbers to varify his assertions with. A simple call to Eaton with reference to those numbers requesting a description of the device would remove all of the intregue.
The MB breaker is a molded case breaker as opposed to an insulated case , power breaker, for air ciruiit breaker.