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 the types of power panels you may encounter in the home (circuit breaker or fused); and how to turn off just a branch circuit (just one circuit in the home) and 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. Below that main breaker you will have 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 typically be 30 amp or higher and will be controlled by a double pole circuit breaker having two 120 volt breaker spaces.
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 the branch circuit breakers below it. This photo shows a 100 Amp main breaker with the panel face plate removed.

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 turn 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 inside the panel whatsoever. If you are working on an individual circuit 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!)