Bronco9588
Member
- Location
- Kent Island, MD
- Occupation
- Engineer
Thanks in advance for your responses.
I have a heat pump with aux heater at 20 amps and a blower fan at 4.9 amps.
The MCA is 32 amps and the MOP is a 35 amp breaker.
Unfortunately, I read the wrong column (208v vice 240v) and installed a 10ga NM wire and a 30 amp breaker where 8ga wire and 35 amp breaker would have been more appropriate.
Of note, the breaker that came with the heater is a 30 amp breaker and the manual states only 30 and 60 amp breakers are supplied with the heaters. Therefore, the unit's breaker appears to be correct. It is my understanding that unit breakers can be larger than the MOP, but in my scenario, the supplied heater's breaker is less than the MCA specified by the unit,, (yet was a listed heater for the heat pump). Would it be inappropriate to use a 30 amp breaker with 10 gauge wire at the main panel if the unit's disconnect is also 30? My school of thought is upgrading the wire and breaker don't remove the possibility of nuisance trips at the unit's breaker.
Also, the blower motor is an ECM motor and therefore does not have a capacitor. The ECM ramps up to speed instead of having a large starting current surge. The heater starts with a delay after the blower fan starts. Therefore, I do not think the unit would ever see starting current surges above 25 amps plus control wiring.
Do I rewire?
I have a heat pump with aux heater at 20 amps and a blower fan at 4.9 amps.
The MCA is 32 amps and the MOP is a 35 amp breaker.
Unfortunately, I read the wrong column (208v vice 240v) and installed a 10ga NM wire and a 30 amp breaker where 8ga wire and 35 amp breaker would have been more appropriate.
Of note, the breaker that came with the heater is a 30 amp breaker and the manual states only 30 and 60 amp breakers are supplied with the heaters. Therefore, the unit's breaker appears to be correct. It is my understanding that unit breakers can be larger than the MOP, but in my scenario, the supplied heater's breaker is less than the MCA specified by the unit,, (yet was a listed heater for the heat pump). Would it be inappropriate to use a 30 amp breaker with 10 gauge wire at the main panel if the unit's disconnect is also 30? My school of thought is upgrading the wire and breaker don't remove the possibility of nuisance trips at the unit's breaker.
Also, the blower motor is an ECM motor and therefore does not have a capacitor. The ECM ramps up to speed instead of having a large starting current surge. The heater starts with a delay after the blower fan starts. Therefore, I do not think the unit would ever see starting current surges above 25 amps plus control wiring.
Do I rewire?
