AssessmentĪ 100-amp breaker box is typically used in a condo or two-bedroom apartment to put things in perspective. Without an electrician’s guidance, you should only proceed as far as finding and opening the main breaker box. It’s a potentially risky task that should only be attempted by an expert. Regardless of how confident you are with the job, wiring a 100-amp circuit breaker box might be a difficult undertaking that requires the approval of an electrician. To power up the load circuits through Hot, Neutral, and Gerund wire, both tiny circuit breakers and GFCI circuit breakers are linked in the diagram below. As a result, the single Hotwire is linked to both hot lugs, which fed up 120V load points. To achieve just 120V supply voltage, you’ll need to use a jumper wire to connect Hot 1 (the black line) to both hot lugs in the subpanel. You will need all three wires, namely Hot 1 (Line 1 from the 1-Pole Breaker), Neutral from the Neutral busbar, and Ground from the ground terminal, as illustrated. Wiring Installation of a 100A Subpanel for Only 120V

Finally, the electrician installs the feeder breaker in the main service panel’s open double slot.Ĭonsequently, separate circuit breakers for the additional circuits then become ready to be fitted in the subpanel.

Next, the electrician connects the hot feeder wires to a new 240-volt circuit breaker at the main panel and then attaches the neutral and ground wires from the feeder cable to the respective bus bars in the main panel. The electrician attaches the two hot wires from the feeder cable to the lugs on the hot bus bars in the subpanel, connects the neutral wire to the neutral bus bar, and the bare copper grounding wire to the grounding bus bar. A 100-amp subpanel needs #4 copper wires or, more typically, #2 aluminum wires. A three-wire cable with three insulated conductors and a bare copper ground wire is conventional. While installing a subpanel, an electrician generally first runs a feeder cable to the subpanel from the main panel.

100 amp main panel wire size