# Three way switch problem



## Thrifty Tool Guy (Aug 23, 2007)

Hello,

I've completed the wiring on a three way switch set-up for my shop and the switches do work in proper sequence, but the lights are really dim. The circuit is limited to lights, but is downstream of a GFI receptacle. Any thoughts?

Thanks,

TTG


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## kp91 (Sep 10, 2004)

In the intrest of full disclosure, my electrical experience is primarily with 1 and 3 phase ungrounded marine electrical systems. Sometimes it takes me a bit to switch back to household wiring.

First off, what is on the circuit? In my limited experience with GFCI receptacles, I think that you would want your lights to be on the LINE side of the GFCI. I would hate for you to be in the shop and have your lights go out if the GFCI tripped.

Are the lights fluorescent or incandescent? If you've got a voltage drop, you may not be able to get some of the energy efficient ballasts to kick on. One of my former ships (now razor blades) had 106v on the lighting circuit. Only the big, old ballasts would excite the light bulbs. But I digress.

That being said, either the GFCI or something in your wiring is preventing the lamps from seeing the full 120vac. If you can, move the lights to the line side of the GFCI, this should eliminate it as the problem. If that doesn't work, check your wiring. Attached is a page with a bunch of different wiring diagrams for 3 way circuits.

As always, make sure every thing is isolated before you start poking around in it, and if you're uncomfortable with what you're doing seek professional advice.

Hopefully, Cassandra will see this post, she's usually got the answers for electrical stuff.

Installing A 3-way Switch With Wiring Diagrams - The Home Improvement Web Directory


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## Von Bickley (Sep 15, 2010)

TTG,

Have you checked to be sure you have the lights wired up in parallel. If you have them wired in series, they will be very dim.

Unscrew one of the lights, if the other light goes out, they are wired in series.


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## Cassandra (Mar 15, 2006)

Yes, Doug, I did see the post and will reply.

Von's suggestion is the first one that came to my mind. It should be the first test you do.

Press the Test button on the GFCI, to trip the GFCI. The lights should go out if they are indeed wired downstream of the GFCI> 

Another possibility is that lights are not properly wired between live and neutral. Is it possible that the lamps are wired from live to ground instead? Of course, this should trip the GFCI if the lamps are downstream of the GFCI. (A good ground should still light the lamps -- so if the lamps are live-to-ground and dim, then you have a ground problem also.) 

Doug is right on not connecting the lights to the load side of the GFCI. In fact, lights should not be on the same circuit as receptacles. 

Can you do a wiring diagram of the circuit that you wired? There are different ways to do a three-way circuit and I would need to know which way you chose.

Cassandra


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## Cassandra (Mar 15, 2006)

One nasty thought occurred to me after my previous post. Hopefully the lamps are not wired neutral to ground. If they are and they are glowing at all, then you have a serious ground or neutral problem!

Cassandra


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## dutchman 46 (May 23, 2007)

One thing that can help is to wear some rubber gloves. It will help if there is any stray power in the system. of course, disconnect the power. Check the ground system. make sure that You have no bad connections, It can cause electrical hazards from other circuits.


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## Thrifty Tool Guy (Aug 23, 2007)

*Thanks for the info....Parallel vs serial*

Hello,

I really appreciate the information and I think the problem might be parallel and series circuits.......I have both. I've attached a diagram of the circuit with the dim lights (A and D). Lights B and C aren't connected at the moment, but there is current at the wire ends when the single switches are closed. Closing and opening the single pole switches has no effect on the brightness of lights A and D.

What is the correct circuit? Your input is appreciated

TTG


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## Thrifty Tool Guy (Aug 23, 2007)

*Is this the proper circuit?*

Hello,

Is the following circuit viable?

Thanks,

TTG


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## rweerstra (Feb 9, 2010)

Thrifty Tool Guy said:


> Hello,
> 
> Is the following circuit viable?
> 
> ...


The second one will work. In the first you have parallel and series connection to the lamps. They will be dim. Lamps need to be in parallel.


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## del schisler (Feb 2, 2006)

Thrifty Tool Guy said:


> Hello,
> 
> I've completed the wiring on a three way switch set-up for my shop and the switches do work in proper sequence, but the lights are really dim. The circuit is limited to lights, but is downstream of a GFI receptacle. Any thoughts?
> 
> ...


Got a volt meter??? measure the voltage at the 2 light wire's . You should have aprox 120 volt's. Probly around 60 volt now ? could be wired in serries some how. Or you don't have a ground. Do a complete look around. You should be on the right side on the GFI but that wouldn't dorp voltage down. Just do a complete redo. Not that hard to do. Good luck


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## Von Bickley (Sep 15, 2010)

Thrifty Tool Guy said:


> Hello,
> 
> Is the following circuit viable?
> 
> ...


This circuit will work but you will have to turn on the 3-way switch for Lamp B and Lamp C to work.

The first circuit that you showed will not work properly.


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## Thrifty Tool Guy (Aug 23, 2007)

Von Bickley said:


> This circuit will work but you will have to turn on the 3-way switch for Lamp B and Lamp C to work.
> 
> The first circuit that you showed will not work properly.


All,

Thanks for the input. I now have shop lights. Yeah.


TTG


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## Cassandra (Mar 15, 2006)

Hi Thrifty

Good to hear that the lights are on.

The problem with the first circuit is that lamp D is in series with the other lamps. That explains the dimness.

As Ron pointed out, the second circuit is correct, as you can see now.

Cassandra


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## BigJimAK (Mar 13, 2009)

The second circuit would be a logical one for a bedroom if you had two entrances, with "A" and "D" being in the bedroom and "B" and "C" haing spearate switches for his-n-hers closet lights. This circuit would have the advantage of automatically turning off the closet lights when you turn off the bedroom light. This works really well unless you get up before your spouse and want to turn on a light in your closet without turning on the main room lights.


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