Heat Pump Breaker Trips - Richard, my breaker keeps tripping for my heat pump. It seems to be a nuisance trip on occasion, and it usually happens at the most inopportune time. I am wondering what you think could be the problem to prevent these nuisance trips. I want it fixed so my heat pump is reliable. Thanks!!

This is a question sent in by one of the site visitors and is in a series of articles for heat pump troubleshooting and repair.

Heat Pump Breaker Trips

The Heat Pump Condenser Circuit

Based on electrical code, these breakers, as with each breaker in your panel, should be labeled for the appropriate circuit location/appliance. That is not always the case. That is, the panels are not always labeled, and when they are labeled, they are not always labeled properly. It may be necessary for your HVAC technician to troubleshoot this issue to figure which circuit is tripping, the air handler, or the heat pump condenser.

Heat Pump Breaker Trips

A breaker trip for any appliance including a heat pump is usually caused by a dead short in the wiring or a motor. I usually say because there are some cases where the breaker was found to be bad or defective and would give nuisance trips. Once the breaker was replaced, everything worked fine according to normal specifications. A bad breaker can easily be replaced. However, this should be done by a trained professional, and a basic check of other components needs to be done to make sure these components did not cause the breaker to go bad.
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Heat Pump Breaker Trips - NEC

The panel in the photo is an open electrical panel with breakers. The breakers installed must be sized properly for the amp load and wires size. Consult the NEC tables for proper wire sizing based on ampacity. Every electrical component in your electrical system is designed for a specific load or a specific number of amps.

A common residential heat pump condenser will have a number 10 wire which terminates in the main electrical panel to a breaker specifically sized for the ampacity of the condenser. This ampacity calculation is generally on the heat pump condenser on a label provided by the manufacturer.

Components from the termination at the condenser to the termination in the main electrical panel need to be sized according to the listed ampacity rating. The ampacity rating is usually list by the manufacturer. That includes wire size, breaker size, and fuse sizes with the fuses being special-purpose slow-blow fuses to take into account locked rotor amps (LRA) or starting amps for the compressor.

Reasons Why the Breaker Trips for a Heat Pump

Here are the basic reasons that will cause your heat pump breaker to trip along with basic explanations:

• Bad breaker - this is described above. Can also be classified as a loose breaker (described below).
• A dead short - this is when two wires touch and this could be a bad motor or a bad compressor. The windings in the compressor could go bad and when they do they cause a dead short in the windings. A heat pump condenser contains the compressor. If the condenser is fused, it can blow before it trips the breaker. However, it can also trip the breaker depending on the sizing of the fuses and the breaker. A dead short can occur in the air handler or the heat pump condenser.
• Power supply. That can be caused by brown-outs in the summer or by a severe storm with lots of lightning. If some appliances in your home are working properly, then you need to call the power company to have them solve this issue for you.
• Poor maintenance. A dirty clogged air filter or clogged condenser coils will cause the motors and compressor to operate at higher than normal amp draws. That creates a lot of heat from the extra electrical energy used. This not causes a higher power bill but can also lead to heat pump breaker trips. Make sure you properly maintain your heat pump not only to prevent nuisance breaker trips but also to save energy. HVAC preventive maintenance goes a long way in comfort and energy savings.

Heat Pump Breaker Trips

• Mechanical lockup of a motor or compressor. A bad bearing or a rusted bearing can cause the motor or compressor not to start and run properly. That creates a lot of friction, keeping the motor or compressor from moving freely. That will cause the motor to work harder and create a higher amp draw and more heat.
• A bad capacitor including start and run capacitors - Capacitors are essential to single-phase motors. Start capacitors and run capacitors are designed to help the motor run more efficiently and in the case of a start capacitor designed to help the compressor start. A bad capacitor can cause heat pump breaker trips.
• Loose electrical connections - this can include connections to the heat pump itself or even a loose breaker. Loose connections cause a higher than normal power draw. That increases the heat and can lead to other problems that will eventually fail the heat pump.
• Short cycling - Short cycling of a compressor can cause heat pump breaker trips.

Additional questions from our readers:

Conclusion

Remember, safety is very important, and doing any of these things on your own is dangerous. It is best to call a professional to this work and troubleshooting the problem for you. Some people reset the breaker only to have it trip again when the issue recurs. Resetting a tripped breaker over and over again will not solve the root of the problem. Consequently, this needs the attention of a professional.

Heat Pump Breaker Trips

Resource: The Home Comfort Book: The ultimate guide to creating a comfortable, healthy, long lasting, and efficient home