Manual Transfer Switch Planning & Installation Recap

Manual transfer switch installed next to the circuit breaker panel.

Manual transfer switch installed in Garage next to the circuit breaker panel

Installing a manual transfer switch requires planning, a step you should not skip. You can move forward with your installation after you obtain a building permit and know your plan is approved. The plan you presented to the building department included your manual transfer switch installation materials list—don’t make any substitutions until you call and obtain approval for different materials.

The building permit and inspection serve as additional insurance. If a fire were to damage your home, an unauthorized and non-inspected electrical modification could void your home’s insurance policy. A passed inspection tells the insurance company and prospective home buyers that the job was done right.

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Mount the Inlet Box and Transfer Switch

Mount the inlet box in the location you chose while planning the installation and detailed on your permit application drawings. Place the box against the wall, level it with a torpedo level, and mark the mounting holes and cable/conduit locations with a pencil. Drill pilot holes for the screws and the PVC conduit, add some caulk to each hole to seal it, and screw the box to the wall.

A Gen Tran Power Inlet Box mounted on the side of a house with vinyl siding.

Power Inlet Box

Place the transfer switch against the wall on either the left or right side of the main distribution panel as planned. Level the transfer switch with a torpedo level and drill pilot holes for the screws. Screw the manual transfer switch to the wall. Caulk is not required indoors.

Run PVC conduit between the inlet box and the transfer switch. Connect the conduit to the inlet box and transfer switch with watertight connectors. Each length of conduit comes with a bell shaped end for easy connections, or you can make connections using PVC conduit connectors.

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Note: Whenever the turns in the conduit exceed a total 360 degrees, an LB fitting or junction box is required.

Install PVC conduit support brackets every three feet for conduit sized 1 inch or smaller, and every five feet for 1 1/4-inch to 2-inch diameter conduit.

Connect the manual transfer switch to the main circuit breaker panel with PVC conduit and fittings. Connecting the conduit to the load center will require removal of the front panel and a knockout―turn off the main breaker or main disconnect first.

Warning: Always turn off the main circuit breaker before removing the front panel on the service panel. The large lugs that connect the main circuit breaker to the utility wires are always live and cannot be shut off in most circumstances. Do not touch the utility wires or the lugs on the main circuit breaker for any reason.

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Connect the Main Utility Supply

Turn off the main circuit breaker or main disconnect. An externan main disconnect shuts off all power to the circuit breaker panel and circuit breakers, while a main breaker in a panel only shuts off power to the circuit breakers—the two large terminals and wires connecting to the main breaker are always live on a main circuit breaker.

Locate the circuit breakers in the main panel that will move to the manual transfer switch. Label and turn them off. Select two of the breakers that are adjacent and remove them.

If you can’t find two adjacent breakers that will move to the transfer switch:

1. Remove 1 breaker that will move, and an adjacent breaker that will not move.

2. Remove a second breaker that will move from anywhere in the panel. Replace it with the breaker that will not move to the transfer switch.

You now have two adjacent slots in the main panel. Install the new, 240-volt double pole breaker that will supply the manual transfer switch in the two adjacent slots. Feed the four supply wires through the conduit to the manual transfer switch. Strip 1/2-inch of insulation from both ends of each wire.

Pro Tip: Inspectors like neat work. It’s easy to follow and see there were no mistakes. Don’t skimp on wire. Arrange the wires to follow the same path as those already in the main panel. Do the same inside the manual transfer switch.

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Route the wires neatly through the main service panel to their correct locations. Follow the conventions the original electrician used when wiring the box, and keep all the wires neat. Hot wires are usually black, red, or blue. Neutral is white. Ground is green.

Loosen the lug screws on the new main breaker and insert the ends of the hot wires into the lugs. Tighten the screws and torque to the manufacturer’s specification.

Connect the white neutral wire to an empty space on the neurtral bus bar (identified by the other white wires connecting to it.) and the green or bare ground wire to the ground bus bar (identified by the bare or green wires connected to it.) Torque all connections to the manufacturer specification.

The correct torque is important to prevent loose connections and overheating. Don’t skip the torque step.

Note: NEC code requires bonding (electrically connecting) the white neutral bus to the ground bus in exactly one location. For this reason, many electricians use the same bus bar for both neutral and ground in the main service panel. Follow this convention only in the main service panel and only if it was already wired this way.

Important: Always consult a licensed electrician before doing any electrical work on your home ~Norwall PowerSystems

Continue with Manual Transfer Switch Installation: Part 2

Updated July 3, 2026