When a breaker trips (shuts off), it’s usually because too many things were running on one circuit at the same time and it got overloaded. So if you’re running one or more high-amperage appliances like hair dryers, toasters or space heaters, and the breaker trips, just shut off the devices and reset the breaker.
But if the breaker trips for no apparent reason, there may be a short circuit—a much bigger problem, usually best left to an electrician to figure out. A tripped breaker isn’t always easy to spot. If you’re lucky, there will be a list of circuits on the back of the panel’s door and you’ll be able to find the tripped one quickly (sometimes those lists are labeled wrong, however). If not, you’ll have to find it by eye. Look for a partially tripped breaker that’s about halfway between the “off” and “on” positions. Avoid the temptation to switch off and on all the breakers, or you’ll find yourself resetting electronic devices like clocks around the house or losing work underway on computers. You could even damage delicate electronics.
You’re likely to see switches for three different types of circuit breakers in a panel—single pole, double pole and “tandem.” Single-pole breakers feed 120-volt circuits for ceiling lights and most wall outlets, while double-pole breakers feed 240-volt circuits for appliances like electric ranges and central air conditioning systems. “Tandem” breakers also have two switches. They take a single slot inside the circuit breaker panel and turn it into two 120-volt circuits to save space.