The main circuit breaker, usually located inside the main panel at the top, shuts off all of the electricity to the house. In a dire emergency, this is the one to turn off. Otherwise, shut off only the breaker that serves the problem circuit—that way, other parts of your house will continue to have lights and power. The main circuit breaker does not shut off the wires that run from the main panel breakers to the electric meter—these are always hot.

When you open the main panel's cover, be sure there are no exposed electrical wires except for an exposed (non-insulated) solid copper ground wire. A protective panel should conceal all wiring—only the breakers or fuses should be exposed.

If this is not the case, call an electrician to have your electrical panel made safe—touching the wrong wire or bare metal contact in an exposed electrical panel can electrocute you. Never touch bare metal contacts inside a disconnect panel.

To shut off a circuit breaker, simply flip it to the off position.

To reset a circuit breaker, first turn it to off and then flip it to on.

To shut off a circuit protected by a pullout fuse block, grasp the block's handle and pull it toward you. Once the block is out, you can remove the fuse from its mounting clips in the block—a special tool called a fuse puller makes this an easier job.

To shut off a circuit protected by a screw-in fuse, grasp the fuse's glass rim and unscrew it (counterclockwise). Do not put your fingers near the socket.