Programmable timer used to control a porch light

In-wall timers, like this one from The Home Depot, turn a standard wall light switch into a programmable timer complete with 7-day customization, random vacation settings, and a backup battery.

I use the timer to control the porch light over the kitchen door, so there’s no more coming home to a dark house at night or leaving the light on all night be mistake.

Features of In-Wall Programmable Timers

• Automate Functions: In-wall timers can automate lights, fans, pumps, or anything else that can be controlled by a regular light switch.
• Save Energy: By programming the timer to come on only when needed, you can save energy without having to think or worry about it.


Programmable timer interface

• Fully Programmable: Using the 7-day program cycle allows you to set the timer according to your schedule. Many also have a “random” setting to provide irregular security lighting when you’re away on vacation.
• Manual Override: Need more light? You can override the settings with the touch of a finger, and it’ll return to the program in the next cycle.
• Backup Battery: The integrated NiCd rechargeable battery prevents your settings from being erased during a power outage.
• Standard Size: In-wall timers fit inside a regular wall switch box. They come with a cover plate but will also accept standard square cover plates.

How to Install a Programmable In-Wall Timer

Turn off power at circuit breaker

1. Choose Proper Switch: Make sure the timer is rated for the same amperage as your existing wiring. A 15-amp timer will replace most standard light switches.
2. Turn Off Power: Turn off the circuit breaker or unscrew the fuse that controls the wall switch and fixture.
3. Remove Switch Cover Plate: Remove the cover plate and use an electrical tester to verify that the power is off.
4. Unscrew Existing Switch: Remove the screws holding the existing switch in the box, and pull it out, leaving the wires attached.


Unscrew existing switch

5. Inspect Wiring: Before disconnecting the old switch, compare the wiring with the instructions for your new switch. The timer wiring should be similar to your old switch, but the wires aren’t always an exact match, and it can be easy to get confused once everything is disconnected. The new switch should have instructions for different types and ages of wiring systems.
6. Remove Switch Wires: Disconnect the electrical wires from the old switch and remove it.


Attach wires to timer switch

7. Attach Timer Switch Wires: Attach the electrical wires to the timer switch, following the instructions and wiring diagram that came with it. If the ends on the wires are worn, cut them off and strip them the insulation of the ends for a fresh connection. The wires may attach directly to the switch with screws or the switch may have short pigtail wires that are joined to the existing wiring using wire nuts (wrap wires together and turn wire nuts clockwise to tighten). If your house doesn’t have a ground wire, follow the instructions to properly ground the switch.


Insert timer switch into box

8. Attach Timer Switch: Arrange the wires so they fit in the electrical box. Push the timer switch into the box so the flanges on the switch are flush with the wall and aligned with the screw holes in the electrical box. If the box is metal, be sure any exposed switch terminals are not touching the box. Screw the switch to the box with the provided screws. Attach the cover plate, and screw it in place.
9. Turn On Power: Turn the power back on by flipping the circuit breaker on or screwing in the fuse.


Attach cover plate to timer switch

10. Test Switch: Turn the timer switch on and off to make sure it is working properly using the manual switch control. This is often done by pressing on the access panel on the front of the switch.
11. Program Timer Switch: Now comes the fun part – programming your timer! Grab a magnifying glass (or prepare to squint), since the buttons and LCD screen are tiny and can be hard to read. Follow the instructions to set up your timer according to your schedule. Start by learning how to set the clock, then proceed to assigning settings to each day of the week.

Further Information

• GE Smart Digital Timer Installation Guide (PDF 132kb)
• How to Install a Dimmer Switch (video)
• How to Install a Chandelier and Dimmer Switch (video/article)
• How to Install an Outdoor Security Light (video/article)
• Leviton Astronomical Timer For Your Home (video)
• Lutron Maestro Dimmer with Occupancy Sensor (video)