A service panel is an electrical box which takes power from a utility and routes it to various circuits within a structure. The service panel is often located close to the electrical meter, and it is an important component of an electrical system. People should familiarize themselves with the location of the service panel in their homes so that they know where to go if there is a problem with the electrical system.
Structures attached to an electrical grid get what is known as a “service drop,” a connection to the grid which allows the structure to receive electrical power. The size of the service drop varies; a basic household service drop, for example, may be 100 amps. Larger service drops are used for structures like factories, which need far more power to meet their needs.
The service drop travels through the electrical meter, allowing the utility to measure how much power people are using, and then into the service panel. It usually hits what is often known as a “main breaker” first. Having a main breaker is important because it allows people to cut power to a structure with a single breaker. Then, the power is distributed among a series of circuits which are also controlled by breakers. These can include dedicated circuits such as those used for water heaters and stoves, which usually need their own circuits because of high energy draws.
Service boxes are sometimes referred to as fuse boxes. This is a reference to the fact that historically, service boxes used fuses as a safety measure. In the event of a problem with the current, one of more fuses would blow, cutting off power and reducing the risk of fire, shock, and other adverse events. Modern service panels usually use breakers, which have the same function as fuses, but can be reset after they are tripped for safety, rather than needing to be replaced.
It is very important that work on the service panel be performed by a licensed electrician or a homeowner who is very experienced with handling electricity. The service panel can be extremely dangerous to work on. It is also important that people use the service panel to cut power to circuits they are working on, and check those circuits with a voltage tester before starting work. If a breaker trips or a fuse blows, especially repeatedly, an electrician should be brought in to determine why, in case there is an underlying problem with the circuit which poses a safety risk.