Electrical Service Panel: Basics For Homeowners

Inside Electric Service Panel
Inside Electric Service Panel. Fuse/Getty Images

Many home renovators may perform some electrical repairs on their own, but they often avoid the electrical service panel. Here are some basics of this ignored but highly essential part of the electrical system.

Your service panel is the connection between wires coming from the street and your home's electric system.

The service panel is the central distribution point that connects the service wire or service drop, which is the main wire coming from the outside into the house, to the exit wires that split off and service different parts of the house. These exit wires are called branch circuits or branch wire circuits. 

It's the same as a fuse box. Sort of.

The electric service panel used to be called the "fuse box," "fuse panel," " circuit breaker panel," or any number of other terms. Today, most homes have what we call the electrical service panel, or simply, the service panel. It's not literally the same thing, but it does provide the same function.

Some houses really do have a fuse box.

It still applies to older homes. Older homes still have what is best called a fuse box because they have actual fuses which screw or pull in/out. Homes built between 1950 and 1965 may have these 60-ampere fuse boxes, often with 4 fuses. However, homes today have modern electrical service panels.

All of your home's power is located in the service panel.

The electrical service panel provides 100, 200, or more amps of power to a home. Power comes into the house from a "service drop," connects to the lugs within the service panel, and is split into separate circuits throughout the house.

Homeowners are allowed to work on it, but many choose not to.

Most homeowners only have the experience of opening the outer door of the electrical service panel to flip on a disabled circuit breaker. However, it is perfectly allowable for a homeowner to work on the inner section of his or her electrical service panel. For example, it may be necessary for the homeowner to remove and replace a circuit breaker.

Inside are lugs, breakers, and wires.

After removing the outer panel, the homeowner will see:

It is far less complicated than you might think.

It is dangerous to work on.  Especially the service lugs.

Yes. Unlike the shock from a receptacle (which may or may not be fatal), a shock from the lugs will most certainly be fatal or seriously hurt you.

If you touch the lugs, this will almost certainly result in serious injury or death.  

In the panel, two black heavy-gauge wires come into the panel from the top of the box. These are the ends of the service wires that come into your house from the outside. Avoid touching these wires or anything that these wires touch.

While it's often easy enough to be cautious of the things your hands touch, be especially careful of things that you hold. The detached service panel, screwdrivers, wire cutters, wire snippers, pliers--these things can potentially touch parts of the service wires and transmit an electric shock to you.

You can add more circuits and circuit breakers inside your service panel as long as there are spaces.

It is doubtful that all of the available spaces are taken up by circuit breakers. So, yes, it is possible to add more circuit breakers if there are more spaces. Generally, you can determine if there are more spaces by looking at the metal "knock-outs" on the panel itself. Any space that is not knocked out is available to put in another circuit breaker.