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brightlight 07-21-2012 06:33 PM

PICTURES - confused over double light switch wiring - help!
4 Attachment(s)
Hi all,

I am trying to replace a double light switch with fancier switches (movement detectors) but I am quite the novice. I have switched off the power on the main board, but I am lost as to where to connect what, and don't understand why the two switches are connected together with a "bridge". and what's that red wire?

any help would be appreciated. (see pictures below)

k_buz 07-21-2012 06:49 PM

The black wire that goes from one switch to the other is the hot, the wires on the top terminals are the switch leg.

The black on the motion sensor to the hot. The red on the motion sensor to the red. The whites of the motion sensors to (all) the whites in the switch box. The blue gets capped.

AllanJ 07-21-2012 06:53 PM

Cables 1 and 3 -- One is the power feed and one is continuation of power somewhere else such as some receptacles.

Cable 2 -- Black wire is for light 1 and red wire is for light 2.

All cables -- White is neutral and all the whites are tied together.

Blue wire nut in forground bridging the two switches together is to convey the incoming power to both switches and all the way around to the continuation cable.

New switch -- Connect switch black to the feed and continuation blacks in the box. Connect switch red to cable 2 black. Connect switch white to the cluster of whites already there.

Second new switch, connect switch red to cable 2 red.

brightlight 07-21-2012 07:19 PM

thanks for the replies...

I'm sorry to say I'm not 100% what I'm supposed to do here, both scenarios look different to me (I'm really new at this)

my understanding is that you're "optimizing" the original wiring scheme, correct?

so here are my follow-up questions:

1. Allan, what do you mean by light 1 and light 2? is light 1 the single light and light 2 the combination of fan and double light fixture?

2. how do I figure out which one is the feed and which one is the continuation cable out of the two cables?

3. I noticed the "bridge" cable is actually the same black cable which is just stripped, twirled around the terminal, then sent to the blue nut. how will I achieve this with my new switches (three wires in a nut? is that safe?)

4. why am I connecting a white cable to the group of white cables in the box if there was no white cable going from a switch to white cables in the box before?


EDIT: also, shouldn't the hot wire from switch 2 be connected to the hot wire from group formed by the source, continuation cable and switch 1 as well?

joed 07-21-2012 07:40 PM

1. You have two switches, light one and light two.
2.The one stripped in the middle feeding the two switches is the feed. It doesn't matter really which is the feed and which is the continue through. They get connected together so they are the same.
3.Connect the the two existing black wires with the black wires from the switches using a nut.
4.Your new switch needs a neutral connection to work. That is why the whites get connected to the other whites.

FYI "Cable" is an assembly with a bunch of wires. The labels should more properly be called cable 1 cable 2 cable 3.
The black one stripped in the middle connected to the two switches is "wire"

brightlight 07-21-2012 07:55 PM


Thank you so much.

I have another switch to do, this one a 3-way, so I might follow-up with more questions... and pictures lol

Thanks a bunch.

brightlight 07-21-2012 09:24 PM

1 Attachment(s)
OK. Here's another one for you.

I'm sure this one's easy. Basically this light dimmer switch controls two separate overhead halogen lights. One switch, two lights.

My new dimmer switch is of the same kind as the other new switches I just installed. It needs a neutral wire. My thinking is either:

1. The white wire is the wire going to the lights, and I don't have a neutral wire, in which case... what do I do????


2. The white wire is a neutral wire, and I don't need a wire going to the lamps because i'm at the end of a circuit?? ... lol.

EDIT: btw, this is not the 3-way I was talking about in my previous post.

k_buz 07-21-2012 09:30 PM

In this situation the white is not a neutral. This is your standard "switch loop". The white (is supposed to) be the hot and the black is the switch leg. The white should be remarked with black tape or black marker. There is no neutral in the box.

brightlight 07-21-2012 09:34 PM


Originally Posted by k_buz (Post 971331)
In this situation the white is not a neutral. This is your standard "switch loop". The white (is supposed to) be the hot and the black is the switch leg. The white should be remarked with black tape or black marker. There is no neutral in the box.

so what you're saying is in this scenario, the white is the hot instead of the black?

and so no neutral... what do I do? the instructions that came with the dimmer say it needs a neutral... is it optional??

EDIT: btw, how did you know the white and black were inverted? how can I know next time?

k_buz 07-21-2012 09:41 PM

If there is no neutral in that box, you will either not be able to use that dimmer or you will need to run a new wire from the switch box to the fixture box.

As for how I know it, its very common. As of the NEC 2011, neutrals are required at every switch box as more and more lighting controls are requiring a neutral to operate.

LooseSCruz 07-21-2012 09:53 PM

Does that dimmer really require a neutral? It sure doesn't look like it to me.

LooseSCruz 07-21-2012 09:54 PM

Oh sorry, I wasn't reading closely enough. Nevermind.

brightlight 07-21-2012 10:45 PM

The one in the last picture is the old one... the new one is at the begining of the thread...

joed 07-22-2012 08:00 AM

The dimmer in your first pictures needs a neutral. You can't use in the new box without changing the cable to the box and bringing a neutral.

brightlight 08-04-2012 10:53 AM

Moved to seperate thread

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