hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
Can a motor circuit protector be fuse and can it be used in fused disconnects? If yes then link to manufacturer of fuse motor circuit protector?
I don't see any reason why you could not fuse a motor circuit protector. But I don't know what the point would be.Can a motor circuit protector be fuse and can it be used in fused disconnects? If yes then link to manufacturer of fuse motor circuit protector?
I don't see any reason why you could not fuse a motor circuit protector. But I don't know what the point would be.
I also don't see any way to install a motor circuit protector in a fused disconnect. A motor circuit protector is basically a molded case circuit breaker with only an IT element installed. It's not going to fit in a fuse holder.
While we typically call that type of breaker a motor circuit protector, the code only uses the term instantaneous trip breaker. 430.52(C)(3)I don't see any reason why you could not fuse a motor circuit protector. But I don't know what the point would be.
I also don't see any way to install a motor circuit protector in a fused disconnect. A motor circuit protector is basically a molded case circuit breaker with only an IT element installed. It's not going to fit in a fuse holder.
See 430.52(C)(7). The motor short-circuit protector (motor circuit protector) is a fuse device and it has the same restrictions as an instantaneous trip breaker...that is that it can only be used as part of a listed combination motor starter. They cannot be used in a stand alone fused disconnect.
However if you are asking about a standard type fuse in a motor circuit, they can be used to provide the required short circuit and ground fault protection and the required overload protection. This application does not require the fuses to be part of a listed combination type starter. It would only require the addition of some type of motor controller, which could be the fused disconnect.
If the fuses are sized to carry the locked rotor current, they are not sized to provide overload protection. Overload protective devices must be sized per 430.32. Just the type of protective device does not make it an overload device. It is only an overload device where sized to provide overload protection.Oh dear! I have drawings where ahead of fire pump controller they are using fused disconnect with fuse in them. The fused disconnect is a service disconnect. The fuses are sized based on locked rotor current.
Overload protection is not allowed for Fire Pump.
Let me understand what you are saying the drawings cannot you fused disconnect with fuses ahead of fire pump motor controller since fuses have overload and short circuit protection? It has to enclosed circuit breaker?
AND, since it is a Fire Pump, you CANNOT HAVE overload protection.If the fuses are sized to carry the locked rotor current, they are not sized to provide overload protection. Overload protective devices must be sized per 430.32. Just the type of protective device does not make it an overload device. It is only an overload device where sized to provide overload protection.