In this video, you will learn how to install a main breaker panel in your garage. Please note that if you are inexperienced with electrical workings, please seek out a professional at a local electrical installation service provider.
Specifically, this video shows a Square D Homeline 100 amp breaker box. First, make sure it is mounted on a secure board.
In this case, it is on the barn wall and the wires come up through the floor and go out up through the rafters. There are four conductors but only three are used here. A coupling is used to funnel the wires up into the box. Next, you want to connect the three wires to the box. You will have to strip them down at the ends before plugging it in. Then use a screwdriver to tighten them into place. After this, install the safety cards that prevent you from accidently touching the lugs. Next, install the 30 amp duel pole breaker. It should simply snap in. Similarly, the 20 amps should also snap in. Lastly, a wire should come down from the top and plug into the breaker, creating a wire circuit.