How to Wire a Main Breaker Box

Hunker may earn compensation through affiliate links in this story.

Things You'll Need

  • New breaker box

  • Long slotted screwdriver

  • Breakers

  • Wire strippers

  • Allen wrench


Always wear safety glasses.
Tools made specifically for electrical work are the best ones to use when doing this type of project. Follow the instructions on double drinkers to make sure the wiring is installed correctly.
Be certain that the breakers are snapped solidly in place. A breaker for a 240-volt appliance has two wires that connect to it: one black and one red.


Do not work with live electricity.
Never leave the front plate with the door off the breaker box. Never leave an opened breaker box unattended.


Electricity is one of the most dangerous parts of construction. A new project requires a licensed electrician to pass city inspections. However, knowing how to wire a main breaker box can help a homeowner determine issues that may be stemming from the electrical wiring. Before beginning this project, be certain the electricity has been disconnected at the meter loop or the pole.

Step 1

Disconnect the electricity at the meter loop or the pole.

Step 2

Insert the two main lines from the electrical supply pole into the two terminals at the top of the breaker box. Tighten the lugs with either a slotted screwdriver or an Allen wrench. Next, notice four bars that run vertically. Two of these will be flat and carry the electricity to the house breakers. These are called the bus bars. The other two are used to secure the breakers in place by slipping into a notch on the breaker.

Step 3

Plug in the main breaker and move it to the off position. Electrical panel boxes differ some, but there is only one way the breakers will plug in. Tilt the breaker so the notched end slips into place. Then push the breaker over the bus bar until it is secure.

Step 4

Notice the two ground bars on either side of the box. This is where the ground (bare) wires from the house will be connected. They slip into a hole and are held in place by screws. The housebreakers have a place for wires to be attached to them. The difference will be how many amps the breaker will be able to pull. Always follow the manufacturer's instructions.

Step 5

Strip the insulation from the wires one at a time. You should see a black wire, a white wire and a bare wire. The black wire is the one that will connect to the breaker. The white and the bare wires are connected to the ground bar.

Step 6

Attach the black to the breaker itself by inserting it into the slot located at the base of the breaker. You will notice a hole through which a screwdriver will fit. This is the location of the screw that secures the wire to the breaker.


Michael Straessle

Michael Straessle has written professionally about the construction industry since 1988. He authored “What a Strange Little Man,” among other books, and his work has appeared in various online publications. Straessle earned a Bachelor of Arts from the University of Arkansas at Little Rock in professional/technical writing.