Your life may depend on it.

Safety rules you should follow whenever you're working with electricity include:

• Always shut off power at the main disconnect before changing a fuse.
• Always shut off power to the circuit before repairing or replacing a switch, receptacle, or fixture.
• Always tape over the main switch, empty fuse socket, or circuit breaker when you're working. Leave a note there so no one will accidentally turn on the electricity. Keep any fuses you've removed in your pocket.
• Always check that the circuit is actually dead before you begin working on it. Use a circuit tested or voltammeter.
• Always unplug any appliance or lamp before repairing it.