Not many problems bring frustration or concern as much as repeated tripping. If it happens just once, you can easily reset the breaker and the furnace should run as expected. A surge, a spike in power, or a problem with the electrical grid likely caused the tripping.
However, when the furnace breaker keeps tripping, various problems could cause it. Each issue has a specific solution, so keep reading to see what you can try next time the furnace trips the breaker.
Circuit breakers are devices that protect against furnace overload. Briefly put, the circuit breaker protects against risky amounts of electricity from flowing through the wires inside the house. The circuit breaker also protects the furnace’s internal parts against heating and catching on fire when something is wrong.
Circuit breakers have ratings for specific amounts of amps. For instance, a circuit breaker can have a 15amps rating. The circuit breaker will trip the furnace every time it consumes more than 15amps. One can ask how the circuit breaker knows that the furnace consumes more than 15 amps.
Well, the circuit breaker uses heat to detect amps, so the more amps flow through the circuit, the more heat will be produced. If the circuit breaker heats up, it will trip. It’s not difficult to know that the circuit breaker has tripped: the switch will be in the middle and not to the right or left. After you turn it back on, it won’t stay on and will feel somewhat loose. Resetting the circuit isn’t complicated; you only need to turn it off and back on afterward.
What can make the furnace trip the breaker? How can you fix it?
As mentioned, various issues can make the furnace trip the circuit breaker. Keep reading to find out the details.
Closed air vents will block the airflow circulation in the furnace. See that nothing blocks the air vents if the furnace trips the circuit breaker. It’s the same for the ductwork, as air blockage inside will make the furnace trip the circuit breaker. A kinked flex duct or a bent one won’t permit efficient flow.
When the ductwork collapses, the system will have high pressure and the airflow will decrease. Should the furnace operate for a bit and trip the circuit breaker shortly after, there’s probably airflow restriction in the system. It happens because the blower motor struggles to run and makes the furnace heat up. An overheating engine will need more power than usual, which trips the circuit breaker.
To solve airflow restrictions, you need to check out the air filter. If it’s filthy, replacing it is the best solution. Also, check the air ducts for kinks or blockage and see if all air vents are open.
The blower motor is bad
A defective blower motor will make the circuit breaker trip, which can go faulty by seizing up. A seized blower motor will typically cause the circuit breaker to trip. It’s not complicated to see if the blower motor has seized; turning it with your hand will let you know.
When the blower motor feels like grinding or is difficult to turn, it’s time to get a new one. We must mention that sometimes it’s not easy to detect that the blower motor is bad. It will spin by hand but trip the circuit breaker when you turn it on. If so, the windings or the stator core are damaged. When the blower motor has damaged windings or stator core, replacing it is the only solution.
Even the squirrel cage can make the blower motor trip. When the squirrel cage rubs up against the side of the fan housing, the blower motor might get stuck and cause the breaker to trip. You can try re-align the squirrel cage on the blower motor shaft. However, if the motor is fine and only the squirrel cage is damaged, you only have to replace the squirrel cage.
Blower motor capacitor
The circuit breaker might also trip if the blower motor capacitor is defective. You will know that the blower motor capacitor is faulty if the circuit breaker trips when the blower motor attempts to come on. The electric motor consumes a lot of power when it starts up.
In the first two seconds, when the motor starts, there’s an impressive power spike to make it start turning. The incredible rush of power can be enough to trip the circuit breaker under normal conditions. However, the furnace blower motor has a capacitor that acts like a battery. The capacitor will release all of its energy really quickly.
After it starts up, the blower motor will use the capacitor’s stored energy to start running. When the capacitor is defective, the blower motor will look to get its energy from the electrical circuit. The blower motor will trip the circuit breaker even if it only needs a few extra amps to start running.
Capacitors are cheap and easy to replace and you don’t need to call an HVAC technician for servicing.
A short circuit
The hot and neutral wires touching each other will cause short circuits, making the furnace trip the circuit breaker. Ground faults take a plane when the hot wire connects a grounded part (the metal housing of the furnace, for example) or a ground wire. Ground faults and short circuits resemble a lot, as they will both extract significant amounts of current, tripping the circuit breaker.
Defective wiring or bad parts can lead to short circuits and wires touching represent the most common reason for short circuits. Short circuits can also take place when components of the furnace malfunction.
It’s not easy to discover a short circuit in your furnace. Additionally, it’s dangerous because you will have to manage line voltage wiring. If you suspect your furnace has a short circuit, it’s better to call an HVAC technician.
Loose wire
This might surprise you, but loose wires can actually trip the circuit breaker quickly. When the cables are loose, the connection gets weak. Weak connections have high resistance and heat will be generated if that happens. So if the wires heat up, the circuit breaker will trip.
But there are other ways in which loose wires will trip the circuit breakers. It’s common for new houses to have breaker panels with AFCIs (Ard Fault Circuit Interrupters). The AFCIs can protect against arcing faults, which makes them superior to standard circuit breakers. The arc fault takes place when electricity circulates through an unplanned path. If the connection is loose, the electrical current will flow through the air. The electrical arc generates extreme temperatures, which can start fires.
AFCIs present circuitry that finds unintended arc faults. If they detect the arc faults, the circuit breaker will trip to protect against high temperatures, heat, and fires. Always turn off the circuit breaker if you think that loose wiring trip the circuit breaker.
Remember to examine the wiring and make sure that everything is secure. Also, see that all connections are secured by slightly tugging them. If you notice any loose wire, tighten the connection when it’s a screw terminal. Replacing the connector will probably be the best solution if it’s some other type of connection (a fork terminal).
Electrical panel problem
Sometimes, the electric panel could be the reason for the circuit breaker to trip and not the furnace. Damaged breakers will cause irregular performance. If your house is old, you should consider replacing the old electric panel with a new one. An electrician is required for the job.
Also, the furnace should be on an isolated circuit, but this might not be the case for old houses. Check out the labels on the electrical panel and see if the furnace shares the circuit with another appliance. A temporary solution is to unplug the secondary device and avoid using it when the furnace is running. However, in the long run, you should call an electrician and have him set up a dedicated circuit for the furnace.
The circuit breaker itself is defective
When none of the previous factors and fixes eliminate the tripping of the circuit breaker, the circuit breaker itself might be faulty. We want to warn you that the circuit breaker is the last to check out. Most of the time, it’s not a good idea to start by replacing the circuit breaker. More often than not, something else is wrong and makes the circuit breaker trip.
Having said that, you should replace the circuit breaker only after eliminating all other possible reasons. Replacing the circuit breaker is better left to the professionals, so call a certified HVAC technician for the job.
Why resetting the circuit breaker is a bad idea?
Some people think that simply resetting the circuit breaker after it has tripped is an easy fix to the problem. However, this is not wise, especially if the circuit breaker trips again. When the circuit breaker trips, something is wrong with the furnace and you need to detect the issue.
A circuit breaker that keeps on tripping is helpful as it warns you about problems with the furnace. The circuit breaker protects the house’s wires, so when the furnace uses too many amps, the house’s wires will overheat and possibly cause a fire. Luckily, the circuit breaker trips and stops fires from happening. Always look into it when the furnace keeps on tripping the circuit breaker.
