Your electrical panel box houses a large amount of high amperage electricity that is lethal if you come in contact with it. It also houses enough power to cause the panel box to explode in certain serious malfunctions.
The purpose of the main breaker in your electrical panel is to shut off all electricity coming in to the home from the electric utility company. It is usually labelled 100 amp or 200 amps, and is physically larger than branch wiring breakers. Only under the following circumstances should the power be disconnected at the main breaker:
1. An emergency situation that requires immediate disconnection of all household power. (Flooding and fire)
2. Service work on the panel box is required (your electrician’s responsibility)
3. Electrical work elsewhere in the building is required and there is no way to isolate a single branch circuit to the area.
It should never be shut off regularly (like a light switch).
The Electrical Safety Authority gives a danger rating of 10 out of 10 for work involving the electrical panel. It is highly recommended that you hire a licensed professional for jobs involving flooding and fire as well as any service work or replacement of an electrical panel.