Extension cords are made to be used as temporary devices and must be suitably sized for the appliance or device they are supplying. Common household extension cords are generally not suitable for powering heating appliances or devices that use a lot of electricity. Overloading extension cords causes them to heat to a point that could melt their covering and cause a fire. Another frequently found related issue is running extension cords under rugs, carpets or furniture, which allows them to heat up to unsafe levels. Generally speaking an extension cord that is used to power an appliance should be replaced by a suitable hardwired outlet within reach of an appliance’s factory installed cord.