"Let's say you connect [an extension cord] to a floor heater," Martinez says, "the plug melts and it starts a fire. That's why you can't use extension cords and/or power strips for any appliances, because they should be used for electronics only."

Extension cords and power strips are safe for most home and office electronics, but for many appliances, they can be a bad idea.

Exercise caution if you're low on outlets and relying on extension cords. Not all devices are safe to connect this way, and the wrong combination can lead to overheating or even fire hazards.

Extension cords can be a great way to improve productivity and convenience, but it's important to know the dangers of what not to plug into one.