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rockclimber 09-11-2009 05:26 PM

Double switch wiring
 
Hi everyone,
I'm trying to wire up a double switch and can't quite figure it out. I've searched on the net and found a couple diagrams that don't sem to pertain to my situation. Here is my situation....

My wife and i bought a house. The bathroom doesn't have an exhaust fan so i'm in the process of installing one. The bathroom currently has one light wired to a single switch.

I want to add a fan and a double switch so that i can control the light and fan from the double switch. The breaker for this circut is 15 amp. I have taken the switch plate off and there is a 14 - 2 cable entering. With the single switch in the off position the white wire is hot..in the on position both the white and black wires are hot. As there is only one cable entering the box, i believe it means the switch is after the light, and from what i understand the white wire should technically be "marked black".

So with this set up how do i wire a double switch at this location? If i run a section of 14-2 from my fan to this box (so there would now be two 14-2 cables in the box) how would i wire up the switch?

My double switch has two black screws connected by a metal tab on one side (hot), two brass screws on the other side, and a ground screw. Any help would be greatly appreciated. i've never dealt with a double switch before
thanks
RC

SD515 09-11-2009 06:44 PM

First off, the double switch…the 2 black screws connected by the metal tab is the line side. The 2 brass screws are the load side. Incoming power (hot) would be connected to one of the black screws, if you leave the tab in place, it doesn’t matter which one. The loads would be connected to the brass terminals, and therefore be independently controlled by the switches. Piece of cake.

Your setup sounds like the incoming power cable hits the light box first, and then has a switch leg to the switch box. Just running a 14/2 from the fan to the switch isn’t going to work, as you also need to get a neutral to the fan.

If you are going to tap into the light circuit, you either can run 14/3 from the light to the switch and also run 14/2 from the switch to the fan, or you can run 14/2 from the light to the fan and also 14/2 from the fan to the switch. Somehow you have to get the neutral to the fan. Your current switch box setup does not have a neutral in it.

Tell us which way you want to go and we can tell you which wire gets hooked up where.

frenchelectrican 09-11-2009 08:08 PM

There is couple ways you can do this depending if you have attic above if so it will make it little more easier.

You will have to rearrange the switch box so you will need to reconfreaged the exsting 14-2 to normal power feed right now you have switch loop { you will see that on the luminaire right now } due you only have one cable going in there so .,,

one way is bring in 14-2 to the switch box then have two 14-2 out going one for luminaire and other one for new fan { you will have to change two gang box if you going have a dimmer or motion sensor or timer } otherwise sometime you can get by with single gang box { this part I am not too crazy due it don't take much to get the switch box filled up in hurry }

Or go with 14-2 for incomming and 14-3 for outgoing so you can split between the fan and luminaire { if you have room in the junction box or can get into in the attic space without issue }

or make a double switch loop this part is pretty tricky to deal only if you have junction box in the attic { this option is very limited use due you will not have any netural there } but the first option is the best and safest way to do it.

Merci,Marc

rockclimber 09-11-2009 10:02 PM

Thanks for the replies guys. I understand a simple switch loop....i guess what i'm having trouble understanding is how it would (could) work for the two fixtures. SD515 mentions that i don't have a neutral...

I have access to the attic and can find the cables up there. What would be the easiest way? I'd like to fish the least amount of cable possible. I currently only have 14/2 cable (black, white, and ground..14/2 right?) but would be more than willing to purchase some 14/3 if it would make the job easier. Does anybody have any diagrams of the setups your describe? The books that i have don't go into double switches. Diagrams really help me understand the set up......

SD515....i'm trying to understand the two options you describe but can't quite picture it...

maybe this is a bit beyond my current electrical abilities?

thanks again
RC

AllanJ 09-12-2009 12:21 AM

When the replyor has to fabricate a multi-case answer using the word "if" too many times then the replyor is apt to ask the queryor more questions back and forth in order to narrow down and be able to fabricate a more simple reply.

The problem I see is too many wires coming into one box or another and this will affect what solution works best (or will work at all).

Here are my questions: How big is the switch box? How big is the existing light fixture box from which the existing 14-2 switch loop cable comes? Describe all the cables that enter the light fixture box.

If I read the question superficially and decide to second-guess a modest if-less single case answer instead of a long if-filled multiple case answer I would say this:

Run another 14-2 cable from the light fixture box to the switch box (as a power run, not another switch loop). Run a 14-2 from the switch box to the fan location.

Connect black of the new 14-2 at the fixture box to the power feed (probably at a cluster of blacks plus the white of the existing switch loop wire nutted together). Connect white of the new 14-2 at the fixture box to the netural (rest of the whites wire nutted).

Down at the switch box connect the old switch loop 14-2 cable to one of the two switches in the double switch unit. Break off the tab between the two black terminals.

Connect the two new whites in the switch box box together (neutral to fan). Connect the two new blacks to the second switch.

At the new fan box connect up the fan.

rockclimber 09-12-2009 01:32 AM

SD515 - I think the easiest option for me would be to run 14/2 from the light to the fan and run 14/2 from the switch to the fan. How would that be wired up?

AllanJ thanks for your post also. I think the switch box would be too crowded though. I'd like to be able to just stick with the single box but have a double switch. Dunno though if it gets too bad i'll switch to a double box and just use two separate switches.

I've been sitting here drawing diagrams to try and understand what everyone is trying to explain. Pens and pencils everywhere....hahaha. Can anyone recommend a good electrical book for just a homeowner? i'm using "the home how-to handbook, electrical" by rick peters and a general lowes home improvement book. neither touches on double switches. any recommendations for diagrams that SHOW the stuff?

anyhow i'm off to bed. the fan is all installed so i just need to wire it up. hopefully that will get done tomorrow.

cheers
RC

AllanJ 09-12-2009 07:53 AM

14-2 from the existing light to the fan location and 14-2 from the fan location over to the switcfh.

At the light box connect the new white to the neutrals cluster (whites) and the black to the unswitched hot cluster (mostly blacks and where the power feed was attached)

At the switch box connect the new wires to a switch. Bend and snap off the tab between the switches if you are using a double switch. (Connect the old wires to the other switch.)

At the fan box connect the white from the light (power run) to the fan white. Connect the black from the switch (another switch loop) to the fan black. Connect the other two wires to each other.

In all locations connect all ground wires (green and bare) together.

In all locations where a white wire is attached to a switch or to a non-white wire, mark both ends with black or red tape or stain.

SD515 09-12-2009 12:22 PM

AllanJ describes it correctly, but let me also respond. Between the 2 of us, you should be able to understand it. I don’t have a way of doing drawings (I know..it would be nice) but you can follow our instructions and draw it out.

All ground wires get tied together, to the switch, and to any metal boxes. To me, pig-tailing to the switch and boxes is easiest.

Your existing wiring will stay the same, you are just going to tap onto the power feed at the light and run it to the fan, so you have power feed at the fan (this is how you get the neutral to the fan).

A little background review and we’ll get the hardware in place…you have a 14/2 (blk, wht, gnd) power feed coming into the light and a 14/2 (switch leg) going from there to the switch. Re-mark the white of the 14/2 switch leg with black at both ends. This will be your power feed to the switch, the black of this cable will be the return to the light.

Run a 14/2 from the light box to the fan. Run 14/2 from the fan to the switch, and again re-color the white on both ends with black on this switch leg. This switch leg will independently bring power down to the switch and return it to the fan on its black wire.

Pay close attention to the wiring connections….At the LIGHT box…the power feed (existing) cable black gets tied to the white (re-marked black) of the EXISTING 14/2 going to the switch, and to the black of the NEW cable going to the fan. The power feed white gets tied to the white of the NEW fan cable and to the white of the LIGHT. This leaves the black from the LIGHT and the black from the EXISTING 14/2 going to the switch…these get tied together. The light box is done and can be put back together.

At the FAN…(these are both NEW cables) black of the incoming power feed to the white (re-marked black) of the switch leg. White of the incoming power to the white of the fan. Black from the SWITCH LEG to the black of the fan. The fan is done.

At the switch…The 2 black screws are the line side of the switch and are connected together by the metal jumper tab. Most times power is brought into the switch box via one wire, in which case you would leave the jumper attached. In your case you will have 2 power feeds…the whites (re-marked black) from the existing 14/2 and the new 14/2, so you will need to BREAK the jumper tab off. Now the upper black screw should have continuity through the upper switch and out the upper brass screw on the other side. The lower black screw through the lower switch and lower brass screw and with the jumper tab removed, the upper and lower should no longer have continuity between them with the switches in the ‘on’ position.

Attach the white (re-marked black) from the EXISTING cable (light fixture) to one of the black screws. Attach the black of the EXISTING cable to the corresponding brass screw (upper or lower). Attach the white (re-marked black) from the NEW cable (fan) to the other black screw and the black of the NEW cable to the other brass screw. Mount the switch and boom you’re done.

I know…a picture is worth a thousand words and since I don’t have a picture, here’s your thousand words….lol. Draw it out and follow it carefully and you’ll be good to go.

rockclimber 09-12-2009 01:51 PM

SD515 and AllanJ
thanks for all your help.

i'm off to sketch it out so i can better understand and visualize how it will all work. but your descriptions are very useful.

thanks again!
cheers
RC

Wildie 09-12-2009 03:24 PM

The simple solution would be to replace the 14/2 switch leg, with a 14/3 leg.
Then run a 14/2 from the light outlet to the fan.

However, bath fans with a timer is the best arrangement.
With this in mind, I would leave the lighting alone.
I would install a new switch box that can accommodate a timer, then run 14/2 to the fan. The fan would be fed from the light outlet!

rockclimber 09-12-2009 11:03 PM

Thanks again for the help guys. I ended up running 14/2 from the switch to the fan and 14/2 from the light to the fan.

Probably not the neatest way to wire it, but it worked given the materials i had. Best part i learned alot more about switch loops. It runs great...
thanks
cheers
RC

kanna_4 03-14-2011 04:14 PM

same situation - need help
 
Hi All, I'm in the same situation but I dont have access to pull the power from the light to the exhaust fan. So What can I do here ?

As SD515 said
"Your setup sounds like the incoming power cable hits the light box first, and then has a switch leg to the switch box" is my situation.

As rockclaimber mentioned, the power comes from the light(above my Sink) to the switch and now I need to extend the power to the exhaust fan and control the light above my sink and the fan with two switches (one gang). I didnt have any books but I spent 4 hours yesterday and couldnt figure it out.

The gang switch I bought has two switches two black screws on one side and two brass screws on one side and one green screw for ground.

There is a 14/2 from the Light and 14/3 from the fan(but the red wire is not connected to anything). not sure the 14/3 will help anyway.

Just an FYI..note the complex thing is that exhaust fan has a light aswell. I connected the wires as they said in the manual following the instructions to operate both fan and light with the same switch.

Any help is appreciated.

Thanks

SD515 03-16-2011 07:13 AM

Are you saying the switch box had a 14/2 in it, and you added the fan and 14/3 from the fan to the switch?

Some how you need to get power, including the neutral, from the light box to either the fan or the switch. (I know you have power at the switch, you just don't have the neutral)

Do you have access from above or below? Is it a single gang switch box? (and are you going to leave that or make it a 2 gang box?)

If you replace the 14/2 from the light to the switch with 14/3, and you have 14/3 from the switch to the fan, you can use a 3-rocker switch in a single gang box to independently control the lights & fan.

ared 06-09-2011 02:06 PM

me too!
 
I've got a similar issue - installing a ceiling fan outside and I would like it to run to the switch box that controls the floodlights out there on a double switch (with the tab removed). The switch box has one black wire and one white. When I wired up the switch, I got both the fan and floodlights being controlled by the same top switch, one is off while the other is on and back and forth. The bottom of the two switches had no effect.

I could wire them to the floods too...they have also one black and one white coming out this time with a ground that was not connected to anything. How can I set this up? (feel free to talk to me like a 2 year old, I'm just getting started in all this wiring stuff)
Andrew

Wildie 06-09-2011 02:33 PM

Quote:

Originally Posted by ared (Post 664100)
I've got a similar issue - installing a ceiling fan outside and I would like it to run to the switch box that controls the floodlights out there on a double switch (with the tab removed). The switch box has one black wire and one white. When I wired up the switch, I got both the fan and floodlights being controlled by the same top switch, one is off while the other is on and back and forth. The bottom of the two switches had no effect.

I could wire them to the floods too...they have also one black and one white coming out this time with a ground that was not connected to anything. How can I set this up? (feel free to talk to me like a 2 year old, I'm just getting started in all this wiring stuff)
Andrew

This is your problem! "The switch box has one black wire and one white"
There is no neutral in the box, the black and white are just a switch leg.


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