Installing a Garage Door Opener

The opener's rail, which runs between the power head and the door, is shipped in pieces. Assemble as directed by the manufacturer.

The carriage travels back and forth in the rail and connects to an arm that raises and lowers the door. Slip the carriage into its slot and attach the emergency cord.

Bolt the rail to the power head following the manufacturer's instructions. Tighten all fasteners securely.

The limit switches attach to the rail. One of them is adjusted later so it cuts off the motor when the door has closed. The other is adjusted to cut off the motor when the door is completely open. For now attach but don't adjust them. Run the limit switch wires to the power head and connect them.

The bracket that holds the rail needs to attach to the framing. If necessary, nail in a new piece of framing to support the bracket. The framing can be either a vertical piece, as shown here, or a horizontal piece nailed to neighboring studs.

Attach the bracket that supports the rail following the manufacturer's directions. Then support the power head on a ladder, box, or small table so that you can lean the rail assembly against its mounting bracket. Attach the rail to the bracket, tightening the screws or bolts finger-tight. Tighten them firmly once the power head is in place, or as directed by the manufacturer.

Attach mounting straps to the ceiling joists to hold the power head. The rail needs to be at a 90-degree angle to the door. If necessary, add framing so the straps are properly positioned. Hang the power head from the straps. For more on squaring up the rail, see "The 3-4-5 Method" below.

The 3-4-5 Method
Use the 3-4-5 method to make sure that the rail is square to the garage door. The method is based on geometry: If the sides of a triangle measure 3, 4, and 5 feet, the angle opposite the 5-foot side is 90 degrees. Make a mark 3 feet along the door and 4 feet along the rail. The rail is at 90 degrees when the distance between the marks is 5 feet. This method works no matter the units -- feet, yards, inches, or anything else. In a right triangle, the square of the longest side is equal to the sum of the squares of the two shorter sides.

Attach the door arm to the door, then slide the carriage back and forth until it aligns with the upper end of the arm. Connect the arm to the carriage.

Power door openers have safety sensors that stop the door from closing if someone or something is in the way. Attach the sensors -- a light and a photocell -- to the garage door tracks as directed.

Connect the sensor wires to the power head. Route the wires so they will not interfere with the door or carriage.

Garage door openers have switches mounted on the wall so you can open and close the doors from inside the garage. Attach the wall switches, run wires for them, and connect to the power head.

Plug in the unit. Although garage door openers can be hardwired into a junction box, most codes allow you to plug one into a dedicated outlet. Adjust the limit switches and safety sensors.