wiring a double switch

in my basement i have a switch controlling a light that does not produce enough light for the area. i want to install another light. i was told if i used a double switch i could control two separate lights from one electric box. i wired the switch according to the diagram but it works improperly. the bottom switch controls the original light but when i turn on the bottom switch the original light comes on and the new light only glows dimly. what did i do wrong?

 

Please answer some questions:[list=1][*]Is the previously existing switch a regular switch, or a 3-way switch (i.e., is there some other switch that also controls the same light)?[*]Was there a white wire connected to the previously existing switch?[*]You wired the switch according to what diagram? Where did you get this diagram, and what did it say?[/list=1]You likely wired the lights in series, but we need a lot more detail to help you out of the problem. Tell us precisely what you did.

 

sorry for not including all the info.
1. the previous switch was just a regular switch, no other
switches operate the original light.
2. yes, there was a white wire connected to the switch, one
black & one white.
3. the diagram on the box the switch came in. 690-WG,
Combination Device, Two 1 Pole Switches, 15A 120/277VAC
W/Ground.
the diagram on the box for COMMON FEED Two S P switches on the same circuit. Each switch controls a seoarate load. the diagram shows a blk wire to the side of the switch with tab intact, a blk wire to the opposite side of the switch top screw, and a white wire on the bottom screw of the same side.
like i said originally there was only one white & one blk wire. now i have two whites & two blks. since iwas only using three screws, the guy at the hardware store said to hook the two whites together. so i made a pigtail for the whites. hope this helps.

 

I heard a guy at the local hwd store telling a customer that one screw was hot and the other ground on a double pole breaker. {among other things} The first switch had a switch loop run to it. Now you have included a neutral from the second device in it. John is good at explaining this so I will let him have at it but that should get you thinking about it anyway.

 

You have a switch loop. The instructions you followed were not for a switch loop. The problem is that there is no neutral wire in this switch box. This white wire is not a neutral.

There are quite a number of options you have, but your primary problem is getting a source of power (one with both a hot and neutral). Here are some ideas:

• You could run a cable from the existing light, where there is power, to the new light, and then from the new light to the second switch. This would require you to break out the tab on the duplex switch, since you would be using two independent switch loops. You have to be very careful connecting the cable at the existing light -- it isn't done by matching wire colors.
• Or you could run the cable in the other direction. This means a second cable from the existing light to the switch, and then a cable from the switch to the new light.

Post back with which you want to do and I'll provide more information.

 

Okay, then do this:[list=1][*]Run a new 12/2 (or 14/2 if on a 15-amp breaker) from the old light to the box where you want the new light. Call this cable "X".[*]At the old light, you will see two preexisting cables in addition to the new one you just added. The black wire of one preexisting cable will be connected to the black wire from the light fixture (call this cable "S" for the switch loop). The black wire of the other preexisting cable will not be connected to the light fixture (call this cable "P" for the power cable). Connect the black and white wires of the new cable "X" to the black and white wires of cable "P". This will require you to add an extra wire to each of two wire nuts. Do not disturb the other connections (i.e., make sure that everything that was connected before is still connected). You will likely see a black wire connected to a white wire, but don't let that freak you out, and do not "fix" it.[*]Run another 12/2 (or 14/2 if on a 15-amp breaker) from the new light box to the switch. Call this cable "Y".[*]At the new light box, make the following connections: (a) Xb to Yw. (b) Xw to the white wire from the new light. (c) Yb to the black wire from the new light.[*]At the new duplex switch, break out the tab.[*]Then connect the black and white wires from cable "S" to one switch, and connect the black and white wires from cable "Y" to the other switch.[*]Connect all grounding wires together in every box.[/list=1]

 

I wired everything exactly as you directed. My original light works on the bottom switch, but the new light won't do anything. I checked the wires of cable Y @ the switch with a tester, the Yw makes the tester light up, Yb does nothing. I even touched Yw & Yb together to make sure my switch wasn't fried, but still nothing. What next?

 

First, double-check everything to make sure. Go over all my instructions carefully and compare it to what you have.

Then verify that you have correctly identified which cable is "P" and which cable is "S" in the original light box. If you disconnect everything (carefully recording it all before doing so) and test each cable with your tester, you should be able to confirm which cable is "P" because it will be the only one that makes the tester light up.

Then triple-check everything.

 

Doing some research for a similar problem and a I ran across this old post. I drew a diagram of your wiring instructions to help me understand. To make sure I've got this right:

1) Is the white wire from the old light fixture wire-nutted to Pw and Xw?

2) Is the white wire from the old switch (Sw) wire-nutted to Pb and Xb?

3) If the answer to #2 is "yes", shouldn't Sw (and also Yw) be re-coded as hot?

Learning,

Bryant

 

Bryant, welcome to the forum. shires joe hasn't posted here for six months, so I'd be very surprised if he sees or answers your questions.

Yes, the white wires of switch loops should be reidentified at both ends.