Electrical Cautions
Electricity can be dangerous, but if you use common sense, you can work with it quite safely. The most important thing to remember is to always, without fail, turn off the power at the main service panel before working on a circuit. Only use one hand to disconnect or reactivate a fuse or circuit breaker, and keep the other hand in your pocket or behind your back. Before starting work, check the circuit with a voltage tester to make sure that it is powerless. If you follow this rule, you will never suffer an electrical shock.
Confine your projects to outside the main service entrance. Do not go in the fuse/breaker box to add new circuits or into a transfer panel for a backup generator unless you have the professional know-how. You can wire in new circuits, repair old ones, and make countless other improvements, but call a licensed electrician when it is time to hook up the project to the entrance panel. The cost is not prohibitive, and the professional will check your work.

Codes
All electrical procedures and materials are governed by local building or electrical codes. They may prohibit the use of a certain type of cable or require a particular size wiring or minimum number of circuits, for example. The codes are for your protection. You may need a permit before beginning some projects; always consult with a municipal building inspector.

Testing
Testing tools let you know that wiring is safe. Use a neon circuit tester to see whether power is present, an important safety step even when you have tripped a breaker or removed a fuse. Touching the probes to a hot circuit causes an indicator to light. Use a continuity tester when a circuit is turned off to check whether an electrical path is uninterrupted. A multitester, which has a voltmeter on its face, performs both functions and is essential for measuring low voltages.