I'm sure this has been beaten to death on this forum and many other forums. It has been beaten to death at my place of employment as well but we're back on it again.
I'm at an edge case with wire size/fuse size. I have an HVAC unit that has an MCA of 58 amps and an MOCP of 70 amps that is supplied with #6 wire. #6 is good for 65 amps going by the 75°C column so we're definitely good there. I'm wondering about the fuse size. I know the unit MOCP is 70 amps but is my fuse selection at all limited by the wire size, or do I simply look at MCA for wire size and MOCP for fuse selection and be done with it?
I understand that when strictly motor protection is concerned, there are cases where the circuit can be "overfused" relative to the wire size to avoid nuisance tripping at startup. I'm wondering if my situation is one where this is also acceptable. This is in a laboratory environment and not in the field but I'm just curious how this situation would be handled in the field.
I'm at an edge case with wire size/fuse size. I have an HVAC unit that has an MCA of 58 amps and an MOCP of 70 amps that is supplied with #6 wire. #6 is good for 65 amps going by the 75°C column so we're definitely good there. I'm wondering about the fuse size. I know the unit MOCP is 70 amps but is my fuse selection at all limited by the wire size, or do I simply look at MCA for wire size and MOCP for fuse selection and be done with it?
I understand that when strictly motor protection is concerned, there are cases where the circuit can be "overfused" relative to the wire size to avoid nuisance tripping at startup. I'm wondering if my situation is one where this is also acceptable. This is in a laboratory environment and not in the field but I'm just curious how this situation would be handled in the field.
