A generator can be a wonderful tool during an outage, but it can also be extremely dangerous if used improperly. Without a transfer switch, a generator is a fire hazard if it’s online when electricity is restored. Improper connection of a generator to your home’s electrical circuits also endangers service crews working to restore power. If used without ventilation, generators can cause deadly carbon monoxide poisoning. Never use a generator indoors. Don't run large appliances off extension cords if the generator or cord is not rated for the amount of power drawn.