Have the house electrical service disconnected, mount the circuit breaker panel, connect all of the wires, insert the circuit breakers and have the electrical service restored. Make sure all of the wires are properly marked so that they can be connected to the correct bus bars, and mark the breakers once they are installed so that you know which items in the home are controlled by each breaker.
New construction often has the wires labeled; however, if you are replacing or upgrading an existing breaker or fuse panel, you may need to trace the wires to their destinations to properly install the panel. Always check with your local building code enforcement agency for specific building codes on electrical panel installation.
Mount a piece of 3/4-inch plywood, large enough to accommodate the breaker panel, securely to the wall studs where the service entry cable is. Feed the service entry cable into the breaker panel, and screw the panel securely to the plywood. Connect the service entry cable inside of the panel.
Feed the house wiring into the panel through the cable connectors. Connect all of the house wires to the assigned locations in the panel, with the bare copper wires connecting to the ground and the white insulated wires connected to the neutral bar. Install the individual circuit breakers into the 200-amp circuit breaker panel. Write the information for the area or appliance that each breaker controls in the appropriate location on the inside of the breaker panel door.