A service panel is a steel box with a hinged door or lift-up panel on the front. With the door open, you can access all the circuit breakers in the panel. Typically, one panel feeds the entire house, but there can also be another, smaller panel, called. A service panel is a steel box with a hinged door or lift-up panel on the front. With the door open, you can access all the circuit breakers in the panel. Typically, one panel feeds the entire house, but there can also be another, smaller panel, called a subpanel, which may be used to serve a specific area, such as an addition, a large kitchen, or. When you open the panel door, you gain access to the circuit breaker switches, but that's all. And that's as far as most homeowners need to go. However, to get inside the panel to install or replace a circuit breaker, you have to remove the protective cover around the breaker switches, known as the dead front cover. The dead front cover is typicall. The main circuit breaker is a large breaker usually located at the top of the panel but sometimes near the bottom or along one side. It controls all the power of the branchcircuit breakers (the breakers controlling individual circuits) in the panel. Power comes from the utility service lines, flows through the electrical meter on the outside of you. The two thick, black service wires feeding the main circuit breaker each carry 120 volts from the electric meter and feed the two "hot" bus bars in the panel. Circuit breakers snap into place onto one or both of the bus bars to provide power to the circuits. Single-polecircuit breakers provide 120 volts and connect to just one hot bus bar. Double-p. Once the power leaves the electrical service panelthrough the hot wire(s) of a circuit and does its work through the electrical devices (light bulbs, outlets, etc.), the electrical current returns back to the service panel through the neutral (usually white) circuit wire, which is connected to the neutral bus bar. The bar connects to the main servi.