Location Is Everything

The code is a little particular about where you can situate a service panel. In addition to being as close as possible to the service conductors’ entry point, a service panel …

➤ Must have clear access to it (a minimum of a 30-inch wide by 36-inch deep uncluttered space).
➤ Cannot be installed inside cabinets or above shelving or any other encumbrance. It also cannot be installed in a bathroom.
➤ Must have a working space with 61/2 feet of headroom around it.

In other words, the panel has to be in a clear and accessible area, and it must be readily visible to anyone looking for it. You can’t store your skis or bikes in front of it, and you must be able to open the panel door a full 90 degrees until it’s flat against the wall. Section 110-26(d) of the NEC calls for some illumination to be provided around the panel so that you or an electrician can see what you’re doing if you have to access the panel. Although the code doesn’t detail how much lighting you need to supply, you want to be able to comfortably read the panelboard (the breakers) and the panelboard directory inside the door.

Anatomy of an Electrical Service Panel

A service panel must conduct electricity to individual breakers, must receive and
route the current being returned through the neutral conductor, and must provide a
grounding medium for the system. In a sense, it’s the most powerful electrical device
in your system. Remember, the conductors and cable that come into and leave your
service panel include …

➤ Two hot conductors.
➤ One neutral conductor.
➤ One grounding conductor that

originates in the panel. The two hot conductors energize the panel—and thus the breakers—via two hot bus bars, which are located in the center of the panel. The black or red outbound wires are connected to the circuit breakers that clip or slide into the hot bus bars. These wires supply the current to electrical loads throughout your house. The neutral wires are connected to the neutral bus with setscrew terminals. A grounding bus bar connects the various grounding conductors from the circuits to the panel’s main grounding conductor. The grounding bus bar is bonded to the neutral bus bar. This is the only place the neutral and grounding conductors are tied together. In addition to individual breakers, most service panels have a single main service disconnect in the form of an individual breaker or a series of high-amperage breakers connected together. The code requires that you be able to shut the entire panel down with a maximum of six hand movements. (That is, the panel can’t need more than six switches or breakers to disconnect all of your home’s electrical equipment.) An old panel might require up to six moves to shut everything down, but new service panels all have a single main shutoff, as previously described. The code requires that this main disconnect be as close as possible to the service conductors’ point of entry into the building. In other words, you can’t bring the service conductors into one corner of your basement and then install the service panel 15 feet away while exposing the conductors. (Certain exceptions do apply.)

New Service/Old Service Electrical Service

Unless you’re rewiring your entire house (which isn’t likely unless you’re doing a major remodel), you’ll need to connect your new service panel with at least some of the existing circuits. This usually is not included in the cost of the service change. It really depends on the purpose of the upgrade. In addition, if you have an old fuse system, you will most likely replace the following (again, at an extra cost):

➤ The major appliance circuits
➤ The kitchen and bathroom circuits
➤ The water heater and possibly the furnace circuits

Existing branch circuits for lighting often can be left alone and simply tied into your new panel. (Each will have to be checked, of course.) If you are replacing an existing service panel on a three-wire grounded system with a higher-amp panel, you also will need to connect to the existing service. Only when you’re completely rewiring your home can you ignore the existing service and its location.