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Dimmer Switch / Bathroom fan addition

Posted by Jeannie1111 (My Page) on
Sun, Feb 13, 11 at 4:32

I'm trying to install a dimmer switch in my bathroom, but need some advice. I've installed single and 3 pole dimmers, but this situation seems a bit more complicated.

It looks like a previous owner installed a dual outlet off the outlet/light switch just above it. It doesn't seem installed correctly, because one of the bottom outlets doesn't work and I get an 'open ground' reading on 2 of the outlets.

Also, if I plug an appliance into one of the bottom outlets and turn it on, it will turn the light fixture on...very bizarre.

I've made a diagram of how the outlets/switch is currently wired and have a few pictures as well posted at

I would like to be able to install a dimmer switch for a vanity light fixture. I would like to think ahead to installing a bathroom fan in the future as well.

Any advice is greatly appreciated.

Here is a link that might be useful: Bathroom light switch/oulet for dimmer

Follow-Up Postings:

RE: Dimmer Switch / Bathroom fan addition

First off, the green wire should be white. Green should never be used for anything other than ground.

Something seems incomplete here. Where's the light fixture connected into this circuit. As you show it, there's no connection. Also, as you show it, the breaker ought to trip any time that switch is closed as it will short the power feed together.

However, I suspect what you really have is a switch loop rather than the feed to the power. If that is the case, al those receptacles are improperly connected and it's not surprising they behave strangely. There's no way to connect them to such a circuit. Your "Open Ground" is not the ground but the fact that your tester is confused.

RE: Dimmer Switch / Bathroom fan addition


Thank you for your reply. Yes, I see from your explanation that I have a switch loop instead of a feed to the power. Thanks for clearing that up for me.

Do you think it would be best to just disconnect the lower outlet? I don't see why I need it.

Also, would I then be safe to install a single pole dimmer switch in the upper outlet box?

Thank you for your advice.


RE: Dimmer Switch / Bathroom fan addition

I think Ron called it. Your receptacle is connected in series with the light, which is why plugging something into it turns on the light.

Yes, you should remove the receptacle entirely. Once that's done you should be OK with a dimmer replacing the switch.

Just remember that once you install a dimmer you limit your choices for replacement lamps in the light. Most compact fluorescents don't work with dimmers (though a few do).

RE: Dimmer Switch / Bathroom fan addition

Hi David,

Thanks for your message.

Is there any way to put a dimmer switch and outlet side by side in dual box? I would hate to lose all outlets in the bathroom.

I am aware that I am committed to incandescent bulbs with the dimmer switch...that's ok...I would rather have the ability to dim the lights. Thanks for the reminder.

RE: Dimmer Switch / Bathroom fan addition

You can't use the wiring you've got for *ANY* receptacles. You need to pull a second cable.

RE: Dimmer Switch / Bathroom fan addition

Thank you. I'll just remove the wiring from the lower outlet and cover the box and just keep the top switch and outlet. Thank you for all of your feedback and advice.

RE: Dimmer Switch / Bathroom fan addition

Even the top receptacle is BOGUS.

RE: Dimmer Switch / Bathroom fan addition

Hi Ron,

Thank you for the clarification. I will look into pulling a second cable. It seems to have worked this way for many years, but I understand that it is wired incorrectly...

Any idea of the cost for pulling a second cable?

Am I right to assume that the cable has to come from the breaker box? This bathroom is on the second floor and the breaker box is downstairs on the outside wall directly below.

Thanks again for your advice.

RE: Dimmer Switch / Bathroom fan addition

OK, I think I see what's going on here. It appears to me that you have a switch loop there, and someone has used the grounding (not groundED) conductor as a neutral return for the receptacle.

This is hazardous. It can, with the right kind of loose connection elsewhere in the system, energize other electrical boxes AND the metal cabinets of grounded appliances plugged into other receptacles. Imagine what a surprise it is to touch your refrigerator while leaning against the sink, and get knocked across the room!

Get rid of the receptacles entirely. They are a hazard. Connect the green wire to the ground terminal (if any) on the switch, and the black and white wires to the switch.

You will need to have a proper cable pulled for receptacles in the bathroom. No way around it, sorry.

RE: Dimmer Switch / Bathroom fan addition

Hi David

Thanks for your advice. We are having an electrician come by on Wednesday for an estimate to have a proper cable pulled for the receptacles.

Wondering if you can give advice regarding the other bathroom electrical?

It looks like it is wired a little strange as well...It looks like the ground wire is connected to one of the terminals...

I posted pictures at:

Thanks for all of your help!

Here is a link that might be useful: Hall Bathroom light and fan switch / outlet

RE: Dimmer Switch / Bathroom fan addition

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