Wiring to Replace a Switch with a Timer


Old 08-20-12, 07:07 PM
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Join Date: Aug 2012
Posts: 2
Wiring to Replace a Switch with a Timer

Iíve just bought a house and my first project is to swap the light switch that controls my porch light for a timer.

Unfortunately, the wiring diagram provided with the timer doesnít match my electrical box.

The switch is hooked up to a black and yellow wire, and the timer I picked up has black (marked hot), red (marked load), white (marked neutral), and green wires (unmarked).

Hereís a photo of the switch and the innards of the electrical box:

Name:  Porch switch.jpeg
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Name:  Porch electrical box.jpeg
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Its a bit of a rats nest in there, as there are 3 switches to control the porch light, the foyer ceiling light, and the second floor ceiling light (the porch is on a separate circuit from the other two switches).

Is this something I am able to do, or do I need to hire an electrician? Iím still riding high on buying this place and would like to do the work myself, but I obviously donít want to burn down my new home.

Thanks very much for your help.

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Old 08-20-12, 07:39 PM
Nashkat1's Avatar
Join Date: Mar 2012
Location: USA
Posts: 8,470
Welcome to the forums!

Your existing switch may be wired with a switch loop, and there may be no neutral in the box. The "yellow" wire is likely a white wire that has yellowed with age.

To help us determine what is there now, we need you to describe how many cables enter the box, how many insulated wires are in each, what color they are, and where they're terminated or spliced. You could also take a few more pictures, with everything pulled forward, that show all of the wires, their terminations and their splices.

The more clearly we can see what you're seeing, the easier it is for us to come up with effective advice for you.
Old 08-20-12, 08:27 PM
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Join Date: Aug 2012
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Thanks for replying so quickly.

I was digging around inside the box and have a better idea of what Iím looking at now.

Name:  Porch switch 4.jpeg
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At the bottom of the above photo you can see a red and black wire enter the box. These are joined with a wire nut to a white wire that runs to the porch light switch at the left of the below photograph. The other screw on the switch is connected to a black wire that exits the box.

Name:  Porch switch 3.jpeg
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The switch controlling the foyer light has a similar setup. Two black wires enter the box and are joined with a wire nut to a white wire that runs to the switch. The second screw on the foyer light switch is attached to a red wire that exits the box.

The third switch is a 3 way and controls the upstairs hallway ceiling light. It has red, black and white wires that enter the box and are attached to the three screws on the switch.

There is a 3rd wire nut visible in the 1st photograph. This joins two white wires and two yellow wires, none of which are connected to any of the switches.

There are no green or bare copper wires in the box.

Unfortunately, the other two switches and both wire nuts have such little slack I canít pull them out any further to provide a better photograph.

Again, thanks very much for your help.


Edited for clarity.
Old 08-21-12, 05:45 AM
pcboss's Avatar
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Location: Maryland
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The pigtails spliced to the blacks or red should not be white as white is the color reserved for a grounded conductor.

Do you have access to a multimeter? It would be nice to verify the conductors purpose.

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