Why You Shouldn’t Use Extension Cords for Space Heaters

Growing up in a cold climate, I’ve often resorted to space heaters to warm my office or keep cast members happy on film sets. They are convenient, yet not the safest of appliances.

“Using space heaters requires a little bit of understanding of electricity so you don’t overload the outlet,” says Todd Tripp, a licensed general contractor and home improvement expert with JustAnswer. “When you have a small space heater, it’s really easy to think that it’s like a lamp or cell phone charger, but a space heater uses all of the current at an outlet, so nothing else should be plugged in.”

That means space heaters can also easily overwhelm a power strip or extension cord. Plus, many older models lack safety features like automatic shut-offs and tilt sensors.

If you’re pulling your old space heater out of storage for the winter or thinking about buying a new one, here’s how to keep your home safe while running it.

Risks Involved With Space Heaters

Space heaters are generally safe, especially modern ones with multiple built-in fire-prevention features. Still, according to the National Fire Protection Association, they cause nearly half of all home heating-related fires. Besides overheating and electrical malfunctions, some models can also cause carbon monoxide poisoning and deplete oxygen levels, especially in unventilated spaces.

“Less obvious risk lies in their impact on indoor air quality,” says Jon Gilbertson, President and CEO at Chris Heating & Cooling, noting that models with exposed heating elements can burn dust and other particles in the air, releasing irritants that may trigger allergies or respiratory issues. Also, prolonged use can dry out the air, increasing risk of skin irritation, nosebleeds and damage to household items like art, musical instruments and hardwood floors.

To stay safe, always plug space heaters directly into a wall outlet that’s rated for their higher power draw, and don’t plug other high-draw items into that same outlet. Power strips and cheap extension cords are not equipped to handle this extra-current flow and can consequently cause a potential fire.

Why You Shouldn’t Use Space Heaters with Power Strips

Space heaters draw a lot of power, which most power strips can’t handle, says Joel Worthington, President of Mr. Electric. “This can overload the power strip, causing melting, overheating and sparking, which can lead to a fire,” he says.

That might not happen all at once, so the danger might not be immediately apparent, says Gilbertson. “Their internal wiring often uses thinner gauge material than wall outlets, which degrades faster under high heat,” he says. “Over time, this can lead to micro-damages, creating hidden fire hazards even when the strip seems to work fine.”

The dangers are escalated when multiple devices are plugged into one strip since that increases the electric load on the power strip. Since power strips are often on the floor, they’re more exposed to dust or carpet fibers— which can ignite under these overheated conditions, says Gilbertson.

(It never hurts to take extra measures to learn how to prevent home fires.)

Why You Shouldn’t Use Space Heaters With Extension Cords

CHARISE WILSON PHOTOGRAPHY/GETTY IMAGES

Similarly, as with power strips, many extension cords are not made to handle the electric load of space heaters, which means they are apt to overheat, melt or spark.

“Additionally, the resistance in the cord can cause a voltage drop, reducing the heater’s efficiency and potentially damaging its components,” says Gilbertson. “And using extension cords with space heaters potentially can cause micro-arcing.”

Micro-arcing is small electric arcs that can happen when an extension cord’s plug is slightly loose or the prongs don’t fit snugly into the heater’s plug. Over time, this degrades both the cord and the heater’s plug, creating hidden damage that can lead to overheating or even electrical fires, says Gilbertson. “This risk is heightened because these arcs are often undetectable without specific tools, making the danger invisible until it’s too late,” he says.

What to Do When I Run Out of Plugs

Worthington says the safest thing to do is unplug non-essential electrical items or those not in use so you have a dedicated outlet for your space heater. Prioritize electrical items by using a power strip only for those with a low electrical draw.

Alternatively, you can buy a heavy-duty power strip, which is designed for high-wattage appliances and includes a surge protector and an automatic shut-off feature to prevent overloading. “But still, be very careful with that!” says Gilbertson. “Or you can use rechargeable battery-operated heaters instead. They don’t need outlets and are ideal for short-term, portable heating.”

Extension cords are available in heavy gauges that can handle high-draw appliances like space heaters. Be sure to buy one with a higher amperage and wattage rating than your heater, and check it periodically to make sure it’s not warm, as that’s a sign of danger.

Tips for Using a Space Heater Safely

To keep yourself safe and warm while using a space heater:

• Plug space heaters directly into wall outlets;
• Don’t plug anything else into an outlet while the space heater is plugged in;
• Maintain at least three feet of space around the space heater from all items, especially clothing, drapes and books;
• Locate them away from high-traffic areas where they could be a tripping hazard;
• Only use space heaters on flat surfaces;
• Place space heaters on ceramic tile or on top of a metal sheet if you’re using them on a carpeted floor;
• Face them toward open space, with the front and sides clear of anything that can heat up and cause a fire, including walls;
• Buy models with safety features, including automatic shut-off, tipping shut-off and overheating protection. “It’s also very important to have a space heater that has a thermostat that will shut it off automatically when it reaches temperature in the area,” says Tripp.
• Turb off space heaters when not in use, when no one is in the room and while you’re sleeping;
• Never use space heaters in wet areas;
• Keep smoke alarms in working order;
• Choose one of the safest space heater models;
• Follow all manufacturer recommendations;
• Keep the cord fully uncoiled while in use to avoid overheating;
• Inspect the cord regularly for wear, cracks and other damage; and
• Be aware that space heaters dry out the air, which can increase the risk of static sparks. “A humidifier can balance moisture levels, improving safety and comfort simultaneously,” says Gilbertson.

And, of course, avoid plugging the heater into a power strip or extension cord that’s not rated for the task. “Always use a dedicated wall outlet to prevent electrical fires, or even better, use a smart outlet that cuts power if the heater runs for too long or exceeds a set wattage,” says Gilbertson.

About the Experts

• Jon Gilbertson is president and CEO at Chris Heating & Cooling, a family-owned company based in Chicago, where he began his career as a technician.
• Joel Worthington is President of Mr. Electric, a Neighborly company, and an expert electrician with decades of experience in the field.
• Todd Tripp has been a licensed general contractor and property maintenance manager for more than 30 years. He also answers hundreds of questions from homeowners seeking advice, as a home improvement expert with JustAnswer.

Sources

• Steve Leasure is vice president of operations at Rainbow Restoration, a Neighborly company.