01 of 05
Controlling Power at Your Home Electrical Service Panel
In most any electrical home repair project, you will need to safely turn off the power either to just one circuit or to the whole house.
This tutorial will describe how to turn off just a single branch circuit, as well as how to turn off all the power in the home by turning off the main power disconnect.
Most homes have a power panel using circuit breaker overload protection. As you see in the above photograph, the circuit breaker panel will have a main disconnect circuit breaker of 100-amp,... 150-amp or 200-amp size—or possibly even more, in a very large modern house.
Below that main breaker, you will see multiple branch circuit breakers which control over-current protection to the various circuits in your home. These breakers are usually 15-amp or 20-amp if they are 120-volt circuits. If they are 240-volt circuits, they will be controlled by a double-pole circuit breaker occupying the same space as two 120-volt breakers.Continue to 2 of 5 below.
02 of 05
Turn Off the Main Circuit Breaker
You will see a large double-pole circuit breaker at the top of the power panel, called the "Main." It controls all the power to all the branch circuit breakers below it—effectively controlling the power to the whole house. This photo shows a service panel with the cover removed, exposing the 100-amp main breaker. (In most situations, you will NOT remove the panel cover in order to turn off the power. )
Circuit breakers are controlled with a lever that places it in the "On" or "Off" position.
To... turn the power off to this panel containing the main breaker, simply flip the lever to the "Off" position. This will now disconnect all power feeding the panel and the branch circuits.
Turning the main power off to the panel is required when you are replacing a breaker or adding a 120- or 240-volt circuit or doing any work whatsoever inside the panel. (These are jobs only for a licensed electrician, or a very experienced DIYer with lots of experience with wiring.) If you are working on an individual circuit—such as when replacing an outlet receptacle or light fixture— and cannot identify the branch circuit breaker, then sometimes turning off all the power by using the main disconnect is a way to proceed. (Just be prepared to reset all your clocks!)Continue to 3 of 5 below.
03 of 05
Turn Off a Branch Circuit Breaker
Before working on any circuit—such as when replacing a switch or upgrading an old outlet to a GFCI outlet, for example—you must turn off power to the circuit feeding the switch. And that is the purpose of the branch circuit breakers.
Find the circuit breaker controlling the circuit you are working on. An easy way to do this is to use an electronic circuit breaker finder.
Once you find the circuit breaker, simply flip the breaker to the... "Off" position.
If you do not have an electronic circuit breaker finder, you should use an inexpensive neon circuit tester to test the switch or outlet terminals after switching the circuit breaker to the off position, in order to make sure that the power has been shut off.Continue to 4 of 5 below.
04 of 05
Turn Off a Circuit at a Fuse Panel
If you have an older home or apartment you may find that you do not have circuit breakers but rather, a fuse panel or fuse box.
The fuse box is the equivalent of the circuit breaker's electrical service panel, in that it is a metal box with a hinged cover that houses and controls the incoming electrical service and distribution to branch circuits within the house. It provides overcurrent protection through the use of fuses.
Continue to 5 of 5 below.
05 of 05
Turn Off Main and Branch Circuit Fuses
Main power to the fuse panel is controlled with cartridge fuses housed in a block that simply pull out to disconnect.
Turning Off Branch Circuits at a Fuse Box
Branch circuits are controlled with fuses having threaded ends that screw into sockets in the fuse panel. These large threaded sockets look like light bulb sockets and are called Edison sockets.
However, there are several types of fuses that go into these sockets. To disconnect power to a branch fused circuit, you unscrew and remove the... fuse controlling the circuit with which you are working.
Since you will not be able to use an electronic circuit, you should use an inexpensive neon circuit tester to test the switch or outlet terminals and make sure that the power has been shut off.