Can a Space Heater Blow a Fuse?

Space heaters are a popular way to provide supplemental heating in homes and offices, but they can also be a potential source of electrical issues if not used properly. One common concern is whether a space heater can blow a fuse or trip a circuit breaker. In this comprehensive guide, we’ll dive deep into the technical details and provide you with a hands-on understanding of this phenomenon.

Understanding the Power Demands of Space Heaters

Space heaters typically draw between 1,200 and 1,500 watts of power, which can be a significant load on a home’s electrical system. To put this into perspective, a standard 15-amp circuit can handle a maximum continuous load of 1,800 watts (15 amps x 120 volts = 1,800 watts), while a 20-amp circuit can handle up to 2,400 watts (20 amps x 120 volts = 2,400 watts).

When a space heater is used on its highest setting, it can draw up to 15 amps of current, which is close to the maximum capacity of a 15-amp circuit. If there are other appliances or devices running on the same circuit, the total load can easily exceed the circuit’s rating, causing the breaker to trip or the fuse to blow as a safety measure.

The Role of Circuit Breakers and Fuses

can a space heater blow a fuse

Circuit breakers and fuses are designed to protect electrical systems from overloads and short circuits. They act as safety devices, interrupting the flow of electricity when the current exceeds the safe limit for the circuit.

The National Electrical Code (NEC) requires that each circuit be rated for a maximum of 80% of its ampere rating. This means that a 15-amp circuit should not be loaded with more than 12 amps of continuous current. Exceeding this limit can cause the circuit breaker to trip or the fuse to blow, preventing potential fire hazards and other electrical issues.

Factors That Can Contribute to Blowing a Fuse

There are several factors that can increase the likelihood of a space heater blowing a fuse:

  1. High Power Setting: When a space heater is used on its highest power setting, it can draw up to 15 amps of current, which can easily overload a circuit.

  2. Multiple Appliances on the Same Circuit: If the space heater is plugged into a circuit that is already powering other appliances or devices, the total load can exceed the circuit’s capacity, causing the breaker to trip or the fuse to blow.

  3. Aging or Weak Circuit Breakers: Over time, circuit breakers can become less sensitive and less effective at detecting overloads. This can make them more prone to tripping or failing to trip when a space heater is added to the circuit.

  4. Faulty Wiring or Electrical Issues: In some cases, underlying electrical problems, such as loose connections or damaged wiring, can contribute to the space heater overloading the circuit and causing the fuse to blow.

Preventing Fuse Blowouts with Space Heaters

To prevent your space heater from blowing a fuse, consider the following strategies:

  1. Use a Lower Power Setting: If your space heater has multiple power settings, try using a lower setting that draws less current, reducing the load on the circuit.

  2. Unplug Other Appliances: Before using your space heater, unplug any other high-power appliances or devices that are connected to the same circuit to avoid overloading the system.

  3. Plug into a Dedicated Circuit: If possible, plug your space heater into a dedicated circuit that is not shared with other appliances or devices. This will ensure that the circuit has enough capacity to handle the space heater’s power demands.

  4. Monitor Circuit Breaker Condition: Regularly inspect your circuit breakers and replace any that appear to be old, worn, or not functioning properly. This can help ensure that the breakers are able to properly detect and respond to overloads.

  5. Consult an Electrician: If you continue to experience issues with your space heater blowing fuses or tripping breakers, it’s best to consult a licensed electrician. They can assess your home’s electrical system, identify any underlying issues, and recommend the appropriate solutions to ensure safe and reliable operation of your space heater.


In summary, a space heater can indeed blow a fuse or trip a circuit breaker if it draws too much current and overloads the electrical system. By understanding the power demands of space heaters, the role of circuit breakers and fuses, and the factors that can contribute to blowing a fuse, you can take proactive steps to prevent these issues and ensure the safe and efficient use of your space heater.

Remember, electrical safety should always be a top priority, and if you have any concerns or doubts, it’s best to consult a professional electrician to address the root of the problem and avoid the risk of an electrical fire or other hazards.