How to Put Wire in Breaker Box
Whether you are wiring your entire service panel in one go or just adding a new circuit, doing it properly will save you a lot of trouble in the future. If you are doing the entire panel, you should wait until all the cables have been run---the ends should be marked with the destination and dangling around the box. Know where you want the circuit breakers located in the panel so you can bring in the cables neatly, and keep the 120-volt and 240-volt circuits on separate sides. Follow the steps below to put in the wires correctly. Does this Spark an idea?
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Things You'll Need
- Voltage tester NM connectors Utility knife Pliers Screwdriver Wire stripper Black electrical tape
Instructions
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Open the knockouts in the service panel and insert NM connectors in the holes to prevent the cables from being cut by the sharp panel edges.
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Bring the cables through the knockouts and into the box. Slice down the middle of the cable sheathing with your utility knife and use your pliers to strip it away from the wires.
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3
Start wiring the circuits from the top of the box and work your way down. Run each set of wires around the outer edge of the panel to its breaker. Bend the wires as little as possible when inserting into the breaker and neutral bus.
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For regular 120-volt circuits, put the neutral wire in the neutral bus screw that is closest to the breaker. Ground and neutral wires can share the same bus on the main panel, but on subpanels they must be on separate buses. Do not put two neutrals or a neutral with a ground under the same screw. Attach the black wire to the circuit breaker.
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GFCI and AFCI circuit breakers take both the white and black wires. Read the breaker carefully to see which wire connects where. These breakers come with a white pigtail wire that you attach under the neutral bus screw.
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On the 240-volt side, both the black and white wires connect to the circuit breaker. Wrap a piece of black electrical tape around the ends of the white wires to indicate that they are hot rather than neutral.
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Tips & Warnings
When deciding how to organize the circuits in the service panel, try to ensure that the loads are balanced. This means that each hot bus in the center of the panel should carry the same or almost the same amount of current.
