A fellow inspector just asked me a question for which I had no answer.
Our SOP has been to use the manufacturer nameplate and confirm that a package heat-pump unit has the correct wiring and overcurrent protection based on nameplate data.
I've done this for years without questioning until he presented this interesting viewpoint.
A typical unit in our area may list a compressor with no heat installed as
requiring min ckt amps of 12 and a MaxOCP of 40. In that case that is our requirement.
An identical unit may have 9.6 kw of heat added and a nameplate that allows for "single point" connection. The MCA increases to 57 and the OCP to 60.
Again we accept it.
I understand that the compressor has OL protection, but why is it in 1 case the compressor must have a MOCP of 40, yet the same compressor, with the heat strips installed can have a MCOP of 60?
(There is no supplemental protection shown on the wiring for the units)
Our SOP has been to use the manufacturer nameplate and confirm that a package heat-pump unit has the correct wiring and overcurrent protection based on nameplate data.
I've done this for years without questioning until he presented this interesting viewpoint.
A typical unit in our area may list a compressor with no heat installed as
requiring min ckt amps of 12 and a MaxOCP of 40. In that case that is our requirement.
An identical unit may have 9.6 kw of heat added and a nameplate that allows for "single point" connection. The MCA increases to 57 and the OCP to 60.
Again we accept it.
I understand that the compressor has OL protection, but why is it in 1 case the compressor must have a MOCP of 40, yet the same compressor, with the heat strips installed can have a MCOP of 60?
(There is no supplemental protection shown on the wiring for the units)