Quick question: Do I use a Non-Fusible or fusible disconnect outside next to my heat pump? Or does it matter.

Thanks,
Dano

 

Unless your instructions for the unit call for fuse protection you can use a non-fused pullout disconnect.

 

There is a definite application for a fused disconnect, but it doesn't occur that often in residential work. Assuming you have a 50 amp circuit, if you have reently replaced your old unit with a new higher efficiency unit, the manufacturer may call for a MOCP of 35 amps or 45 amps. In these cases, you would use the fusible disconnect and fuse it to match the MOCP rating. Most residential heat pumps and A-C condensing units operate with between a 20 and 40 amp circuit. Many times the circuit breaker size can just be reduced to match the MOCP rating on the new unit.

Some units don't use the MOCP terminology, but will list a "Maximum Fuse Size". I have seen some inspectors who see this different terminology and then require fuse protection at the disconnect rather than allowing the circuit breaker to provide the protection.

 

If the unit says fuse protection you cannot have just the breaker to protect the circuit.