Before starting any work, you must disconnect the circuit you’ll be working on at its source in the service panel. If your circuits are protected by fuses, removing the appropriate fuse disconnects the circuit from incoming service. In a service panel equipped with circuit breakers, you can disconnect a circuit by switching its breaker to the OFF position.
To make sure you disconnect the correct circuit, turn on a light that’s connected to the circuit before you remove the fuse or turn off the circuit breaker. The light will go out when you’ve removed the correct fuse or turned off the correct breaker. If you have any doubt about which fuse or breaker protects which circuit, shut off all current coming into your home at the main disconnect
While you’re at your service panel, spend another moment to prevent a possible disaster. Tape a note on the panel explaining what you’re doing so no one will come along and replace the fuse or reset the circuit breaker while you’re working on the wiring.Then either carry the fuse with you in your pocket or tape the circuit breaker in its OFF position.
With the electricity turned off, you can work in complete safety. Still, it’s a good idea to keep a few additional safety precautions in mind.
Remember that water and electricity don’t mix. Never work on wiring, fixtures, switches, or appliances when you’re wet or standing on a damp spot. Lay down dry boards to stand on if the floor or ground is wet.
An external handle controls contact with two main fuses in the cabinet. When you pull the handle to the OFF position, you shut off the main power supply.
The main cartridge fuses are mounted on one or two nonmetallic pullout blocks. By pulling firmly on the hand grips, you can remove the blocks from the cabinet and disconnect all power.
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