Space heaters give warmth to the cold corner of your house. They can even do it cut your heating bill during cold weather when used as a strategic substitute for heat throughout the house.

However, these portable warmers can also cause problems, especially if used incorrectly or in the wrong locations.

Heat heaters are a leading cause of house fires in the US during the winter months, but many of these fires are preventable with proper placement. It is important to keep an eye on your space heater while it is on and never leave it running unattended. It is also important to avoid placing it in places that increase the risk of fire.

For a safe, warm winter, here are nine places your space heater is absolutely unnecessary.

Read more: The Best Space Heater

1. On a rug, carpet or flammable surface

Space heaters cannot sit on any surface that is flammable or combustible. That means you can’t put one on a carpet or rug. You should also avoid using it on more delicate hardwoods or soluble vinyl, especially for long periods of time.

What if you only have carpet in a cold room? You can look for a ceramic or otherwise heated base to put under the heater. It should be larger than the heater itself by about 3 inches on all sides.

2. Close to walls and furniture

Your space heater needs a safety zone: Keep it at least 3 feet away from any walls or furniture to avoid fire hazards. Unfortunately, this also means that under your desk or dining table is a void. Try pointing space heaters at these areas instead of placing them directly under them.

3. Close to blankets, pillows or curtains

Space heaters become a greater fire hazard if someone accidentally places a blanket or pillow against them — and in the winter, that can happen easily. This is also true if the heater is pushed against any hanging curtains. Keep all of these flammable items at least 3 feet away from the heater at all times.

4. Anywhere easily accessible to pets or small children

Space heaters can catch fire easily if not careful, and while many newer models have automatic shut-offs if they fall over, a dropped space heater can still be a serious fire hazard. Also, pets and children may not care where they put toys or blankets, creating additional risks.

Use space heaters in areas where children are very small and large pets unable to access or rarely visit. When they pay attention, teach them to give the heater a wide bed.

5. Bathrooms and laundry rooms

Heaters do not play well around water, which affects operation and greatly increases the risk of electric shock. They are also more at risk of tipping in these environments.

Unfortunately, bathrooms and laundry rooms often suffer from brrr-level temperatures when heating is inadequate. We suggest placing a heater outside these rooms for maximum effect and safety.

6. Plugged in with many other appliances or lights

Heaters are large drain amps used in an electrical circuit. That’s usually fine for newer 15-amp outlets in the house, because modern space heaters are designed to work with them. The circuit and breaker that governs that room/area have their limitations.

Plugging in a space heater along with a bunch of other appliances (kitchen appliances, large entertainment systems, etc.) can overload the system. At best, the breaker will trip, and the power will be cut off. At worst, it overheats the wiring and causes an electrical fire.

Read more: 7 Things to Never Plug into an Extension Cord or Power Strip

This risk of overload is also more common in the colder months because the holidays often lead to plugging in more decorative lights, which further increases the amp load on home circuits. You can help minimize problems by alternating devices to reduce overall power consumption and by monitoring with smart plugs.

7. Plugged into an extension cord or power strip (or both)

Extension cords and power strips are not necessarily rated for the required power space heaters, and can increase the risk of an electrical fire, even if the outlet and breaker can handle the heater. Plugging the extension cord into a power strip before connecting the heater only adds to the danger.

If you need a heater somewhere out of the way, look for a model with a wireless power cable. Some extension cords are designed to support higher amperage appliances, but you should be very careful when pairing them with a heater — we’d rather you avoid them altogether.

8. Plugged into an old or non-GFCI outlet

A ground fault circuit interrupter is a small piece of technology that shuts down an outlet when there is a problem with its current, especially if it completes a circuit elsewhere. This is a useful protection against shocks, overheating devices and other issues. Always make sure your space heater is plugged into a GFCI outlet.

Also, avoid plugging the heater into an older outlet or one that has had problems in the past, such as suddenly not working. This increases the risk of causing damage to cables and resulting in fires.

9. Be close to anyone with winter allergies

Winter allergies mostly due to dust, dust mites and particles that accumulate during closed winter days. Those types of allergies are bad when a device blows hot air around a room. That’s especially true if a heater or room hasn’t been cleaned recently and there’s a lot of built-up dust that can be spread around. If someone has very sensitive allergies, try to avoid using the space heater near them and see if you can find other ways to heat.

Final tip: Never use fuel heaters indoors

only use electric or radiant heaters indoors. Do not use heaters that require fuel, such as kerosene, propane or other gas, indoors — including the garage.

Firewood always produces flue fumes, and those fumes require a dedicated vent to escape the home (like a gas fireplace). Without venting the fumes, these heaters will fill closed spaces with carbon monoxide, which can lead to carbon dioxide poisoning, the worst news. The exception is some oil-filled heaters that don’t actually burn oil, but these are rare.

Read more: The Best Smoke Detector

Remember, when you go out or sleep, remember to turn off the space heater — don’t leave it unattended inside your home. For more home safety tips, check out dangerous mistakes that homeowners make during firesTHE best ways to prevent thieves and the perfect worst spots you can put a security camera.

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