The common indoor heater can be a warm friend or a deadly enemy – and it often depends on where you place it.

Radiators are a huge loss of energybut they excel at heating small rooms and spaces that tend to stay cold when temperatures drop. Smart versions can also turn on or off depending on ambient temperatures to save you work.

However, these heaters represent both a significant new load on your electrical system and a heat source that can quickly turn into a fire hazard. This is why Heating methods like this are the second leading cause of residential fires in the United States. But you can eliminate risk from the start by avoiding these huge problems in your heating setup (yes, even your small office heater).

Learn more: The best radiators

1. On any rug, carpet or flammable surface

Radiators must not be placed on a surface likely to burn or catch fire. This means you can never place one on a rug or carpet. You should also avoid using them on more delicate hardwoods or fusible vinyl, especially for long periods of time.

What if you only had carpet in a cold room? You may want to look for a ceramic or otherwise heat-resistant base to place under the radiator. It should be larger than the radiator itself by about 3 inches on each side.

2. Near walls and furniture

Your heater needs a safety zone: keep it at least 3 feet from any walls or furniture to avoid the risk of burns. Unfortunately, this also means no getting under your desk or dining table. Try aiming radiators towards these areas instead of placing radiators directly underneath them.

3. Near blankets, pillows or curtains

Radiators pose an even greater fire risk if someone accidentally puts a blanket or pillow against them – and in winter, this can easily happen. The same applies if the radiator is pushed against hanging curtains. Keep all such flammable items at least 3 feet from the heater at all times.

4. Anywhere pets or small children can easily access

Space heaters can easily burn unwary people, and although many newer models feature an automatic shut-off if knocked over, a dropped space heater can still pose a serious fire hazard. Additionally, pets and children may not be careful where they place toys or blankets, which can create additional risks.

Use heaters in areas where very young children and larger pets I can’t access it or rarely go there. When they pay attention, teach them to leave plenty of room for the radiator.

5. Bathrooms and laundry rooms

Heaters malfunction near water, which can affect their operation and significantly increase the risk of electric shock. They also tend to be at greater risk of falling over in these environments.

Unfortunately, bathrooms and laundry rooms often suffer from too high temperatures if there is a lack of heating. We suggest positioning a heater outside of these rooms for maximum effect and safety.

6. Plugged in with many other devices or lights

Heaters consume a lot of amps that an electrical circuit uses. This is usually suitable for new 15 amp household sockets, as modern heaters are designed to work with these sockets. But the circuit and breaker that manages this room/zone have their limitations.

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

Learn more: 7 things to never plug into an extension cord or power strip

This risk of overloading is also more common during colder months, as holidays often lead to more light decorations being plugged in, further increasing the amp load on home circuits. You can help alleviate problems by placing appliances on alternating schedules to reduce overall electrical loads and monitor 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 power the heaters require and can increase the risk of an electrical fire even if the outlet and circuit breaker can handle the heater. Plugging an extension cord into a power strip before connecting the heater only increases the danger.

If you absolutely need a heater in a remote location, look for a model that comes 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 prefer you avoid them altogether.

8. Plugged into an old or non-GFCI outlet

A GFCI is a handy piece of technology that shuts off an outlet if there’s a problem with its electrical current, especially if it looks like it might complete a circuit elsewhere. It is a useful protection against shocks, overheating of devices and other problems. Always make sure your heater is plugged into a GFCI outlet.

Likewise, avoid plugging the heater into a particularly old outlet or one that has already experienced problems, for example one that suddenly no longer works. This increases the risk of wiring damage and resulting fires.

Final tip: never use fuel heaters indoors

Only use electric or radiant heaters when indoors. Never use heaters requiring fuel such as kerosene, propane or other gas in indoor spaces, including the garage.

Fuel will still create exhaust fumes, and these fumes need a dedicated vent to escape the house (like a gas fireplace does). Without exhausting the fumes, these heaters will fill enclosed spaces with carbon monoxide, which could lead to carbon dioxide poisoning, the worst news. The exception is some oil heaters that do not actually burn oil, but these are relatively rare.

Learn more: The best smoke detectors

Remember, if you go out or go to bed, remember to turn off the heater – never leave it on and unattended inside your home. For more tips on home safety, visit dangerous mistakes made by the owner during a forest fireTHE the best ways to deter burglars and the absolute Worst Places You Can Install a Security Camera.