My garage has a light connected to a switch and a garage door opener. The garage door opener was hard wired to a line coming out from the space between the porcelain light fixture and the ceiling. The opener was not connected to the switch.

The garage door opener died. I am having a new one installed. The salesman told me I must have a ceiling plug installed before they will put in the opener.

I shut off the power, went up and opened up the fixture. The guy that wired this up some 35 years ago had two lines going into the light box. inside they were wired together and one set came out around the base of the porcelain fixture and into the garage door opener. It looked like a kluge but worked for 35 years.

I could not imagine why the lines were twisted together, since the light is connected to a switch but the opener is not. but I needed to separate them so I could pull out the garage door opener set and connect them to a receptacle I installed in the ceiling as required by the installer. I did so and the receptacle works fine. But the light does not light.

Now there are four wires in the light box: black, red, white and ground.

None have power now. I tested each pair with a multimeter with the switch in both positions. Nothing.

Any ideas as to what might be up here?

Thanks in advance.

Open up the switch box, and have a look how it's wired. Without more information (photos, diagrams, etc.), the following information is an educated guess.

One of the colored lines (red, black) is likely always hot, while the other is controlled by the switch. The white is most probably neutral, and the bare/green is almost certainly ground.

If this is the case, then connecting the devices is simple.

  • Connect all the grounding conductors together.
  • Connect the incoming white wire to the white wire going to the receptacle, and to the white wire for the light.
  • Connect the always hot colored wire to the hot wire leading to the receptacle.
  • Connect the switched hot colored wire to the hot wire for the light.

Again, this is a guess based on the limited information you've provided.

  • We must have been typing at the same time, This is very common configuration. + – Ed Beal May 18 '16 at 17:30

This is not a kludge, he took 2 hots off 1 circuit. To add an outlet tie the white for the outlet to the white in the lamp box. tie the grounds (copper wires together). Now tie your black to the red. connect the black to the outlet brass colored screw, white to the silver screw and copper to green screw on the outlet.

  • I am confused. There are two separate circuits which entered the box, one switched and one not. They were then spiced together in the box and a combination of wires went to the light (red and white) and another to the opener. I took the two circuits apart and fed the un-switched one to the plug. No combination of the remaining wires now has power, even though they enter the box as a single cable. – Fred Gray May 18 '16 at 21:38
  • If you go back to the switch you will probably find the switched hot and just prior to the switch the common hot. This is if they are both on 1 breaker. If they are on 2 breakers they should be side by side and the handles tied like a 240 breaker this is called a multi wire branch circuit both are using the same ground and neutral but each is a 120V circuit. Both methods are legal. At the age of the house I would believe he saved some money and time by running 12-3 W ground or 14-3 with ground. – Ed Beal May 18 '16 at 21:59

If this installation has only a single switch for the light (not a 3 way or coming on automatically with the garage door opening). I think it is likely that power was fed to the light fixture first where the black incoming was nutted together with the black to the garage door opener and the black wire to the switch, the white from the power wire nutted to the white from the opener and white to the light, and the white coming from the switch nutted to the red wire at the light and all the ground wires twisted together.

If that sound like the way yours was, simply tie the white to the light and black to the switch back into the power wire you've used to connect the receptacle.

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