Extension Cord Fire Hazard: What Not to Plug In and Why

The extension cord fire hazard that federal safety officials describe starts with heat and damage. The U.S. Consumer Product Safety Commission (CPSC) says, "Overheating is usually caused by overloading or connecting appliances that consume more watts the cord can handle." Federal agencies and safety groups name items that belong in a wall outlet instead, starting with space heaters and major appliances. ESFI calls an extension cord a temporary solution.

Picture a family in Pomona running a space heater off a thin cord behind the couch on a cold night. This guide explains what federal safety agencies say not to plug in, how to choose and check a cord, and what job sites must follow.

The Extension Cord Fire Hazard in Numbers (2019 Figures)

The Electrical Safety Foundation International (ESFI) article Reaching to Safety: Use Extension Cords Properly (2019) says: "Roughly 3,300 home fires originate in extension cords each year, killing 50 people and injuring 270 more." ESFI's extension cord safety page also says "an extension cord is a temporary solution and is not meant to be used as a long-term extension of your household's electrical system".

CPSC's guide, Household Extension Cords Can Cause Fires, explains the two main causes. Cords overheat when overloaded, and "Damaged extension cords can also cause fires."

What Not to Plug Into an Extension Cord

Space heaters

This is the clearest rule from federal safety officials. In a January 23, 2026 CPSC winter safety release, the agency says to "Plug electric space heaters directly into a wall outlet" and "never into an extension cord or power strip". The same release says CPSC estimates portable heaters "are involved in an average of 1,600 fires per year, resulting in an average of 70 deaths and 150 injuries annually from 2020 to 2022".

CPSC also advises keeping portable heaters "at least three feet away from drapes, furniture, bedding and other combustible materials" and turning heaters off when sleeping. The same ESFI article lists not using "an extension cord or power strip with heaters or fans".

Refrigerators, stoves, washers and dryers

The U.S. Fire Administration's appliance and electrical fire safety page says to "Always plug major appliances" such as "refrigerators, stoves, washers and dryers" directly into a wall outlet. It adds: "Never use an extension cord with a major appliance. The extension cord can overheat and start a fire."

Another extension cord or power strip

ESFI says not to "plug extension cords into one another". Its tips page also says: "Multiple plug outlets must be plugged directly into mounted electrical receptacles; they cannot be chained together." USFA adds, "Do not overload power strips."

More than one appliance at a time

ESFI's tips say: "Do not use an extension cord for more than one appliance." Each extra load adds heat to a cord that may not be rated for it.

How to Choose the Right Cord

CPSC's guide gives specific buying and use advice:

• "Extension cords should be at least 16 AWG, unless they are 18 AWG with fuse protection."
• Check the cord's rating on its tag or packaging before you use it.
• "Only use an extension cord outdoors if it is marked for outdoor use."
• Choose cords listed by a recognized national testing laboratory.
• Look for "safety closures, polarized blades and a large plug face that covers the outlet's slots".

ESFI adds that cords should be "properly rated for their intended use, indoor or outdoor, and meet or exceed the power needs" of what you plug in.

Warning Signs and Everyday Habits

CPSC says: "If any part of the extension cord is hot while in use, it is a warning sign that it may be overloaded." ESFI goes further: "Never use a cord that feels hot or is damaged in any way."

Placement matters as much as the cord. Follow these habits from CPSC, ESFI and USFA:

• "Do not run extension cords under carpets, through doorways or under furniture." (CPSC)
• Do not "Nail or staple extension cords to walls or baseboards". (ESFI)
• "Replace worn, old or damaged extension cords right away." (USFA)
• "Never alter a cord to change its length or perform inadequate repairs such as taping up damaged insulation." (CPSC)
• "Unplug an extension cord when it is not in use." (CPSC)
• "Never force a 3-prong cord into a 2-slot outlet." (USFA)

If you rely on cords every day, ESFI says "heavy reliance on extension cords is an indication that you have too few outlets" and recommends having more outlets installed. Homeowners in Los Angeles or San Bernardino can ask a licensed electrician about it.

Extension Cords on the Job Site

In California, job sites fall under Cal/OSHA, the state-run plan administered by the Department of Industrial Relations. Federal OSHA's flexible cords page explains the construction-standard rules. It notes that "A flexible cord may be damaged by door or window edges, by staples and fastenings, by abrasion from adjacent materials, or simply by aging." Under its construction standard, OSHA says:

• "Extension cords must be 3-wire type so they may be grounded, and to permit grounding of any tools or equipment connected to them."
• Cords must be rated for hard or extra-hard usage, with the type letters "indelibly marked approximately every foot along the length of the cord".
• Cords must connect to devices and fittings "in ways that prevent tension at joints and terminal screws".

OSHA also warns that "When a cord connector is wet, electric current can leak to the equipment grounding conductor." For more on the trade itself, see our post on whether electrical work is a good trade to get into.

Frequently Asked Questions

Can I plug a space heater into an extension cord?

No. CPSC says to plug electric space heaters directly into a wall outlet, never into an extension cord or power strip. CPSC also advises keeping heaters at least three feet from drapes, furniture and bedding, and turning them off when sleeping.

What gauge extension cord should I use?

CPSC says extension cords should be at least 16 AWG, unless they are 18 AWG with fuse protection. Check the rating on the cord's tag or packaging, and make sure it meets the power needs of what you plug in and is marked for outdoor use if used outside.

Is it normal for an extension cord to feel warm?

CPSC says a cord that is hot anywhere while in use is a warning sign that it may be overloaded. ESFI says never to use a cord that feels hot or is damaged. Unplug it, reduce the load, and replace the cord if it is worn.

Safer Wiring, Fewer Surprises

Good cord habits protect homes and job sites alike. For electricians and contractors, business coverage is also worth reviewing as your work and crew change. At Farmers Insurance - Young Douglas, our agents explain business coverage options in plain terms, and our advice library covers more trade topics. Coverage depends on your policy. Get a free quote and coverage review.

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Written by LaMonte Douglas, owner of Young Douglas Insurance, a Farmers Insurance agency serving California from Ontario. CA License #4091974.

Sources (accessed September 23, 2026): CPSC, Household Extension Cords Can Cause Fires; CPSC, Keep Warm and Safe This Winter (January 23, 2026); ESFI, Extension Cord Safety Tips; ESFI, Reaching to Safety: Use Extension Cords Properly (October 19, 2019); U.S. Fire Administration, Appliance and Electrical Fire Safety; OSHA, Electrical: Flexible Cords; OSHA, California State Plan.

Last updated: September 23, 2026.