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-   -   dimmer 'crossfade' when combining light circuits (http://www.diychatroom.com/f18/dimmer-crossfade-when-combining-light-circuits-125519/)

mitchl 12-03-2011 10:21 PM

dimmer 'crossfade' when combining light circuits
 
My rookie DIY skills are failing, as is my google-fu to find help. Thought I'd try a post.

I'm replacing a dual light switch with a dual dimmer (Lutron Skylark S2-L), controlling two different ceiling lights. When I opened the existing wall box, I found four wires, what I believe are two hots and two wires, one to each light. However the new dimmer switch has only three connections: a single hot and two wires, one for each light. At the recommendation of the local hardware store, I capped one of the hots, and wired the rest as you'd expect (hot to hot lead on the dual dimmer, each light to the remaining two dimmer leads).

Weirdness resulted: If dimmer 1 (light 1) is up, bringing up dimmer 2 doesn't change light 2. If dimmer 2 (light 2) is up a faint light is seen on light1, and then raising dimmer 1 both increases light 1 and *decreases* light 2. A crossfade effect.

Not sure where to go from here, but is there a way to get this setup working, short of installing an additional 'gang' in the wall and installing separate single dimmers? Is capping and combining circuits really the right method?

Thanks for any help in creating a more subdued ambience in these rooms!

gregzoll 12-03-2011 10:41 PM

For one, people that work at hardware stores are idiots, unless they are retired from the trades, and doing this to keep busy. Follow the directions as stated in the PDF. Post picture also of the current setup as you have it right now, before making changes.

DannyT 12-03-2011 11:00 PM

you say there were only 4 wires total plus grounds? sounds like they might just be switch legs with only 4 wires and that could explain why the dimmer doesn't work properly.

joed 12-03-2011 11:54 PM

That dimmer is made to control two fixtures. The black wire on the dimmer goes to power(the two hots). The red goes to one fixture and the yellow goes to the other fixture.

dmxtothemax 12-04-2011 12:18 AM

First you need to identifie the wires,
Most likely two of them are hots (power in),
And the other two are feeds to the two lights.
use a non contact tester to find the two hots!
the other two are most likely feeds to the lights.
You will only need one of the two hots. (assuming the capacity is adequate) for both lights.
Cap off the unused one.
One wire in to the dimmer,
and two out (feeds).
Easy as !
I hope your dimmer doesnt need a neutral,
cause there might not be one.

mitchl 12-07-2011 09:12 AM

1 Attachment(s)
Thanks for the responses! A photo wasn't doing justice, so I've sketched out a before/after of the wiring, below.

Danny - I'll need to understand switch legs more, but my understanding was that these are used in 3-way wirings (two switches, one light), which isn't the case here (?)

Joead, Dmx: your descriptions are spot on with my understanding and what I (believe) have wired up. Incidentally, following the PDF linked in my first post strayed from reality at Step #3. The double switch I'm replacing had what I believe are two leads, and the break-off fin had been removed.

I'll have to get a voltmeter to start debugging further, but here's the diagram if there are other insights.

In case it's hard to read, on the BEFORE side, the top wire pair/switch includes black wire, painted white, with a yellow marker tape to the +LEAD, and a yellow wire, painted white. The bottom wire pair/switch includes a black wire w/ blue tape to the +LEAD, and an orange wire.

On the AFTER side, I wired the three lead dimmer as follows:

black, painted white w/ yellow marker (+LEAD) -> BLACK
yellow, painted white -> RED
orange -> YELLOW
black w/ blue tape -> (CAPPED)

Attachment 42158

Thanks again!

dmxtothemax 12-07-2011 11:11 PM

Quote:

Originally Posted by mitchl (Post 788075)
Thanks for the responses! A photo wasn't doing justice, so I've sketched out a before/after of the wiring, below.

Danny - I'll need to understand switch legs more, but my understanding was that these are used in 3-way wirings (two switches, one light), which isn't the case here (?)

Joead, Dmx: your descriptions are spot on with my understanding and what I (believe) have wired up. Incidentally, following the PDF linked in my first post strayed from reality at Step #3. The double switch I'm replacing had what I believe are two leads, and the break-off fin had been removed.

I'll have to get a voltmeter to start debugging further, but here's the diagram if there are other insights


In case it's hard to read, on the BEFORE side, the top wire pair/switch includes black wire, painted white, with a yellow marker tape to the +LEAD, and a yellow wire, painted white. The bottom wire pair/switch includes a black wire w/ blue tape to the +LEAD, and an orange wire.

On the AFTER side, I wired the three lead dimmer as follows:

black, painted white w/ yellow marker (+LEAD) -> BLACK
yellow, painted white -> RED
orange -> YELLOW
black w/ blue tape -> (CAPPED)

Attachment 42158

Thanks again!

A non contact tester would be simplier in your case,
Because a volt meter will need a neutral,
And there might not be one in the j box,
Unless its a grounded metal j box.

oberkc 12-08-2011 07:09 AM

Quote:

For one, people that work at hardware stores are idiots, unless they are retired from the trades, and doing this to keep busy. Follow the directions as stated in the PDF.
That was harsh. In fairness, it sounds to me as if the person at the hardware store provided good advice, based on what he/she was told. Unfortunately, the instructions are based on a wiring configuration (power supplied at switchbox) that may not exist at mitchl's house.

It seems to me that the effect described in the original post may be the result of misidentifying which of the original wires are "hot" and which are the returns to the fixture. My guess is that one of the hots was wired to either the red or yellow wire. I suspect that once the hot is properly identifed and the swith wired accordingly, it will work fine.

mitchl 12-11-2011 04:00 PM

Picked up a voltage tester. Explained what I was doing to someone at the hardware store, and since I had a grounded junction box, that was the rec.

Worked out well in identifying hot wires, but it just confirmed my original suspicion (the two blacks are hot). The only thing I discovered is that they are on the same circuit (I originally suspected different circuits). Breaker on, the two blocks are hot. Breaker off, they are not.

The last thing I tried is to switch which hot lead was capped, and which was wired to the dual dimmer. Didn't think it should matter since they appeared to be the same line. Powered everything on, one dimmer worked, brought up the second, heard a pop and smelled an electrical smell.

So, shut it all off, wired up the original on/off (not dimmer) dual switch that I've been trying to replace. I'm thinking it's time to turn it over to an electrician...

Thanks for the help, all. If I can gather what the final solution is w/ the pro, I'll post.


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