Can a Space Heater Be Used with an Extension Cord?

The use of a space heater with an extension cord is generally not recommended due to the significant risks and potential hazards associated with this practice. Space heaters require a substantial amount of electrical power to operate, which can cause the extension cord to overheat and potentially catch fire. This is because the cord may not be rated to handle the high current draw of the space heater, and the increased resistance in the cord can lead to it heating up and failing.

Understanding the Risks

According to the Electrical Safety Foundation International (ESFI), extension cords should not be used as a long-term solution and are not intended to be used as a permanent extension of your electrical system. Overloading an extension cord or using it for more than one appliance can significantly increase the risk of fire.

The primary reason why space heaters and extension cords should not be used together is the potential for the extension cord to become overloaded. Space heaters typically draw a large amount of current, often in the range of 10-15 amps or more. This high current draw can cause the extension cord to overheat, leading to the insulation breaking down and potentially igniting nearby combustible materials.

Technical Specifications

can a space heater be used with an extension cord

To understand the risks better, let’s dive into the technical specifications:

  1. Extension Cord Ratings: Extension cords are designed to handle a specific amount of current, measured in amps. The cord’s rating must match or exceed the power requirements of the space heater. Using an extension cord that is not rated for the load can lead to overheating and fire hazards.

  2. Cord Size and Length: Larger-gauge extension cords (e.g., 12-gauge or 14-gauge) can handle higher current loads than smaller-gauge cords (e.g., 16-gauge or 18-gauge). Additionally, longer extension cords have more resistance, which can also contribute to overheating.

  3. Cord Condition: Extension cords should be in good condition, with no visible damage or wear. Damaged cords can create additional resistance and heat buildup, further increasing the fire risk.

  4. Cord Placement: Extension cords should never be coiled or buried under carpets, furniture, or other items, as this can prevent proper heat dissipation and lead to overheating.

DIY Tips

If you must use an extension cord with a space heater, consider the following tips:

  1. Cord Rating: Always check the rating of the extension cord before using it with a space heater. Ensure that the cord is rated for the high current draw of the space heater.

  2. Cord Type: Use a heavy-duty, high-gauge extension cord (e.g., 12-gauge or 14-gauge) specifically designed for high-power appliances like space heaters.

  3. Cord Placement: Avoid coiling the extension cord or placing it under carpets, furniture, or other items. Keep the cord in an open, well-ventilated area to allow for proper heat dissipation.

  4. Cord Load: Never overload the extension cord by plugging in multiple high-power appliances. Use the extension cord for the space heater only.

  5. Cord Monitoring: Regularly check the extension cord for signs of overheating, such as discoloration or a burning smell. If the cord feels hot to the touch, unplug the space heater immediately and discontinue use.


In summary, while it may be possible to use a space heater with an extension cord in certain circumstances, it is generally not recommended due to the significant risks and potential hazards associated with this practice. The safest and most reliable option is to plug the space heater directly into a wall outlet that is rated for the high current draw of the appliance. Always follow the manufacturer’s instructions and safety guidelines to ensure the safe operation of your space heater.


  1. Extension Cord and Space Heater Safety – Harper College (
  2. What is the reason for electric heaters saying to never use an extension cord? – DIY Stack Exchange (
  3. Can you use an Extension Cord with a Space Heater? (Risk & Fire Hazards) – Heater Tips (
  4. Verify | Do space heaters catch fire if you plug it into a power strip? – ABC News (