Furnace Keeps Tripping Electric Breaker: Reasons and Solutions

If your furnace frequently trips the circuit breaker, it could be a sign of underlying electrical issues.

Understanding the common causes and solutions can help you address this problem effectively and safely, ensuring your home remains warm and safe during the colder months.

Published: September 17, 2024.

Understanding Your Furnace's Electrical System

Furnaces are integral components of home heating systems, especially in regions experiencing harsh winters. While generally reliable, they can sometimes cause electrical breakers to trip, posing not only a nuisance but potentially signaling serious electrical issues that could affect the safety of your home.

This problem can stem from a variety of electrical malfunctions within the furnace or the household electrical system itself. Understanding the reasons behind these trips can help in diagnosing and resolving the issue promptly to ensure the continuous, safe operation of your heating system.

How Furnaces Use Electricity

Most modern furnaces use electricity for several functions: running the blower motor, powering the ignition system, operating controls, and, in the case of electric furnaces, heating elements. The amount of electricity used varies significantly based on the furnace type and its efficiency.

For instance, the blower motor in standard furnaces often consumes the most electrical power, particularly when it starts up, which is a common moment for circuit breakers to trip if there are underlying issues.

Key Components Related to Electrical Use

Understanding the key electrical components of your furnace can aid in troubleshooting and maintaining optimal performance:

• Blower Motor: Drives the air through the ductwork and is often the primary consumer of electricity in the system.
• Control Board: Serves as the brain of the furnace, managing and monitoring every cycle and operation, including safety checks and thermostat responses.
• Ignition System: Can be either a pilot light or an electronic ignition, which requires electricity to ignite the burner.
• Heating Elements: Found exclusively in electric furnaces, these convert electrical energy into heat and are major electrical consumers.

Each of these components must function within the design specifications to prevent excessive electrical draw that could lead to breaker trips.

Common Reasons Why Furnaces Trip Breakers

Overloaded Circuits: The Basics

An overloaded circuit is one of the most common reasons for a furnace tripping the breaker. This happens when the current flowing through the circuit exceeds its capacity, causing the circuit breaker to shut off to prevent overheating and potential fire hazards.

In homes with older electrical systems or where multiple high-energy appliances share a single circuit, this issue is particularly prevalent.

Furnaces require a considerable amount of power, especially upon startup, and if other appliances are drawing power from the same circuit simultaneously, it can easily become overloaded.

Short Circuits in Furnace Wiring

Short circuits occur when electrical flow takes an unintended path, often where insulation has broken down or wiring has come loose. This can result in a sudden spike in electrical current, which can trip the breaker.

In furnaces, short circuits typically happen due to aging wires, rodent damage, or poor connections. Identifying and correcting short circuits quickly is crucial as they pose significant safety risks.

Mechanical Failures Leading to Electrical Overload

Mechanical issues in the furnace, such as a failing blower motor, a stuck fan, a clogged air filter, leaking air ducts, blocked air vents, etc., can also cause the system to draw excessive power.

For example, if the blower motor bearings are worn out, the motor may require more electricity to overcome the resistance, leading to an overloaded circuit.

Similarly, a fan that is obstructed or jammed may cause the motor to work harder, increasing electrical draw to dangerous levels.

Faulty Installation and Its Impacts

Improper installation of a furnace can lead to numerous electrical problems, including frequent breaker trips. This might be due to incorrect sizing of the wiring or circuit breaker, or poor connections made during installation.

Ensuring that your furnace is installed by a certified professional and regularly inspected can help avoid these issues.

Diagnostic Steps to Identify the Problem

Initial Checks and Safety Precautions

Before attempting any diagnostics, ensure the safety of your environment. Turn off the main power supply to the furnace to prevent any electrical hazards.

Verify that the area around the furnace is clear of flammable materials and that the furnace itself is clean and free of debris. Always use insulated tools and wear appropriate protective gear when working on electrical components.

How to Test Your Furnace’s Electrical Components

To pinpoint the cause of the breaker trips, you can perform several tests on key components:

• Blower Motor: Use a multimeter to check the motor's resistance. Anomalously high or low resistance can indicate problems.
• Control Board: Inspect the control board for any signs of damage or burnt components, which can cause short circuits.
• Wiring: Check all visible wiring for signs of wear, damage, or looseness. Ensure all connections are tight and secure.
• Capacitors: Test the start and run capacitors if applicable, as faulty capacitors can prevent motors from starting, leading to high current draw.

These steps will help you understand whether the issue lies with the electrical system or a specific component of the furnace.

Professional vs. DIY Repairs

When to Call a Professional

While some minor troubleshooting and repairs can be handled by a diligent homeowner, there are several scenarios where it is safer and more effective to call in a professional.

If your furnace repeatedly trips the breaker despite basic troubleshooting, or if you identify complex issues such as internal wiring problems, damaged control boards, or failing motors, professional intervention is necessary.

HVAC technicians have the expertise and equipment to diagnose problems accurately, adhere to safety standards, and ensure that repairs are performed correctly, which is crucial for electrical and mechanical systems as intricate as modern furnaces.

Safe DIY Fixes You Can Attempt

For homeowners interested in handling minor fixes themselves, there are a few safe tasks you can perform:

• Cleaning and Replacing Filters: Regular cleaning of the furnace’s filter can prevent airflow restrictions that make the blower motor work harder, thus reducing the risk of tripping the breaker.
• Inspecting and Tightening Electrical Connections: Ensuring that all electrical connections are tight can prevent overheating and electrical arcs that might trip the breaker.
• Thermostat Testing: Sometimes, the issue might be with the thermostat settings or its wiring. Check if the thermostat is functioning properly and is correctly wired to the furnace.

Long-Term Solutions to Prevent Future Issues

Upgrading Electrical Components

To ensure reliable operation and to minimize the risk of tripping breakers, consider upgrading the electrical components of your furnace system. This can include installing higher capacity wires, more robust circuit breakers, and better quality connectors and controls.

These upgrades can accommodate the high power demands of modern furnaces and enhance overall electrical safety.

Regular Maintenance Schedules

Establishing and adhering to a regular maintenance schedule is vital for the longevity and efficiency of your furnace. Professional inspections should be conducted annually, preferably before the start of the heating season.

These check-ups can identify and rectify potential problems like worn-out parts, lubrication issues, or impending electrical failures before they cause your furnace to trip a breaker.

Installing a Dedicated Circuit

One of the most effective ways to prevent electrical overloads is to have a dedicated circuit for your furnace. This ensures that the furnace does not have to compete for power with other appliances, significantly reducing the risk of tripping the breaker.

An electrician can install a dedicated circuit tailored to the power requirements of your furnace, providing a direct and isolated power supply from your home’s electrical panel.

Implementing these solutions can dramatically increase the safety and efficiency of your furnace system, ensuring it provides reliable warmth without electrical interruptions.

Frequently Asked Questions (FAQ)

Here are some of the most common Frequently Asked Questions (FAQ) about furnaces tripping their electric breakers:

How can I tell if my furnace wiring has a short circuit?

To determine if your furnace wiring has a short circuit, start by inspecting all visible wires for signs of damage, such as frayed insulation or exposed wires.

Also, check for burn marks or a burnt smell around the furnace components and wiring, which can indicate a short.

Using a multimeter, test the continuity of the wires; a reading that shows little to no resistance could point to a short circuit. If you suspect a short circuit, it’s advisable to contact a professional technician to safely handle the repairs and avoid potential hazards.

Can gas or oil furnaces trip the electric breaker?

Yes, gas and oil furnaces can trip an electric breaker. Even though these types of furnaces primarily use gas or oil as their fuel source, they still rely on electricity for several components, such as the blower motor, ignition systems, and control boards.

If there are issues with these electrical components, such as short circuits, overloads, or mechanical failures, they can cause the circuit breaker to trip.

This safety mechanism helps prevent further damage or potential hazards.

How do I test my furnace’s blower motor with a multimeter?

Testing your furnace's blower motor with a multimeter involves a few steps to check both the resistance of the motor windings and the condition of the capacitor. Here’s how to do it safely:

• Turn Off Power: Before you start, make sure to turn off the power to the furnace at the breaker panel to avoid any electrical hazards.
• Access the Blower Motor: Remove the furnace cover to access the blower motor. Refer to your furnace’s manual for specific instructions on how to access it.
• Disconnect the Motor: Disconnect the motor wires from the furnace’s wiring harness to isolate the motor for testing.
• Set the Multimeter: Set your multimeter to the resistance (Ohms) setting to test the motor windings.
• Test for Continuity: Attach the multimeter probes to the motor’s wire terminals. A good motor should show a continuous circuit (a numerical reading on the multimeter). If the multimeter shows no continuity (reads infinity or OL), there might be a break in the windings.
• Check for Ground Faults: Move one probe to a metal body part of the motor and the other to each terminal in turn. The multimeter should not show any continuity here. If it does, the motor windings may be grounded (shorted to the motor case), which is a fault.
• Test the Capacitor: If your motor uses a start or run capacitor, unhook it and check it with your multimeter set to the capacitance setting. Compare the reading to the specifications on the capacitor. If it’s outside the specification range, replace the capacitor.
• Reassemble: Once testing is complete and any necessary repairs are made, reconnect the motor, reassemble the furnace cover, and turn the power back on.

If any readings are out of the norm or you are unsure about any steps, it's advisable to contact a professional technician to handle the diagnostics and repair safely.

How often should I replace or clean my furnace filter?

The frequency at which you should replace or clean your furnace filter depends on several factors, including the type of filter, your usage patterns, and the air quality in your home.

Generally, it's recommended to check your filter every month, especially during high-use seasons like winter and summer.

Basic fiberglass filters should typically be replaced every 30 days, while more advanced pleated filters can last up to 90 days.

If you have pets, allergies, or live in a dusty area, you might need to replace or clean your filters more frequently to maintain optimal air quality and furnace efficiency.

For the best offers and prices, feel free to check the Furnace Air Filters Amazon link (the link opens in the new window).

Few Final Words

Furnace breaker trips can be more than just a temporary inconvenience; they often signal underlying issues that require immediate attention to ensure safe and efficient operation of your heating system.

We've discussed several causes, including overloaded circuits, short circuits in wiring, mechanical failures, and the consequences of faulty installation. Proper diagnostics are crucial, involving both visual inspections and electrical testing, to identify the root cause of the problem.

For homeowners comfortable with minor tasks, certain DIY fixes such as cleaning filters, tightening connections, and testing thermostats can be safely performed. However, more complex issues, especially those involving internal components or wiring, should be addressed by professionals.

Regular maintenance and upgrades, such as installing a dedicated circuit, are long-term solutions that can help prevent future issues and ensure that your furnace operates reliably and safely.