Dimmer Switch Wiring

In the wiring standard that is used in the U.S. calls for the white wire (neutral) and the ground wire (green) always run directly from the circuit breaker box to the light fixture with no breaks to the wires. The third wire is black, and is the live wire feeding the fixture. This is the wire that is interrupted by the switch. A dimmer switch is wired exactly as snap on toggle switch. There is also a ground wire attached to the switch, but this is only there to provide a safe path for any current that might escape from the switch from a breakage, or malfunction. So, if your existing snap on light switch was wired correctly, just substitute the dimmer. It is wired the same way.

The only exception I can think of would be if the switch is lighted. In that case, it would also have a connection to the neutral. Good luck.

In the wiring standard that is used in the U.S. calls for the white wire (neutral) and the ground wire (green) always run directly from the circuit breaker box to the light fixture with no breaks to the wires.

I gather you mean that the white wires are not switched instead of having "no breaks". In every home I've owned, and in my shop (which I wired per commercial standards, I hope) the white wires have plenty of breaks, tied together by wire nuts or at carry-through screw terminals on outlets, etc).

That is exactly what I was trying to convay.

Hey K_Fry, after looking over the your wiring schematic link, I noticed the lighting circuits are intermixed with the outlet receptacles. Here in California it's standard practice to have the lighting circuits on their own dedicated 15 amp Circuit Breaker, which can be daisy chained together up to 80% of the expected load of the 15 amp. breaker or about 12 amps. And the outlet receptacles have their own dedicated 20 amp breaker, which can be daisy chained also, but generally limited to one room with spacing the outlet receptacles at approximately on 6' centers. GFI's, the last time I checked, where required within 36" of a water source and all garage outlets. That's the way the code was, the last time I wired homes out here.

Good day sir. Do I see that Lyn-Door Industries has converted to videos from books?

i don't know who rated you OT, but I gave you a GA, it was right on the topic

Thanks.

Dimmer will have two black and one green.

It does NOT matter which wire I connect to in the old switch box, so long as I do NOT connect either black wire from the Dimmer to the green or ground wire in the old switch box?

correct?

Correct.

Something's wrong here. One of those black wires is probably your neutral. With the power on, use a meter, and carefully test between each wire and ground............red meter lead to the wires, black to ground. The one that shows no reading will be the neutral. Mark it with some white tape, paint, etc. This is assuming that the switch was working before. If both black wires are live.....STOP. You've got other issues to deal with first.

Then go here. Be careful.

If there are only 3 wires, and one is green, what else could he have except the power in, and the switched power coming out?

Your right. He had a standard single pole switch.

My mistake. He's still going to have to locate the neutral for a dimmer.

I'm not sure what a "universal" dimmer is, or why it needs a neutral connection; but all the ones I've dealt with are more along the lines of what's already been described. One Green wire and two blacks, the blacks being interchangeable, one to "line", and one to "load", matters not which. I'm guessing the increased complexity of the "universal" (including the "capped" yellow wire) may be because they can be "ganged" to operate as three-way dimmers? Not sure. Here's the type I've installed:

Tom D.

Is that a dimmer of a wind up clockwork motor?

Just a plain-jane slide dimmer made by Lutron, with a toggle on/off at the bottom. Designed for general lighting use.

Tom D.

I can't delete my posts, so just ignore them.

Sure enough, I've only hooked up 3 way dimmers here, and yes, they had the little indicator light on the face.

One of those cases where I should have kept my mouth shut.

It happens.

No, not at all. If anyone else was reading this, and their switch had the white wire, they will be better off for it. Just ignore MY errors.

In your drawing, there appears to be LEDs on the left side of the switch face. These LEDs would be the reason for the neutral connection.

That was my line too....

GA from me. That's good sound advice PWSlack, depending on what type of dimmer they bought, it maybe a simple two wire, power/ load or a 3 way dimmer with or without an indicator. If when in doubt, read the instructions.

Blasphemy!

What would we need CR4 for if we all had directions to read.

I wasn't saying anything was wrong with your replies Bob. Unfortunately, all to often, we seem to either have to be an Oracle or have a crystal ball to foresee what the OP is wanting to do. If we knew that the OP wanted to use dimmers with CFLs, I know your replies would have been different. Kinda like what Lyn said, "it's not rocket science", until you throw in the fact that, they also wanted to control CFLs on the circuit.

Thank you all.

I'll test before wiring it all up just in case. The house is old and I do not remember who wired it but it was back in the 70's for sure.

Bit by bit we are fixing and repairing and it will be almost nice looking just in time for the 2012 Hurricane season! ha ha!

Thank you all again.

The thing I would caution you about if this is a house with additions to the electric service, or if the house is from before the 80s, check that the black and white wire at the fixture are correct. It is common to find the black wire ( live line) direct to the light fixture, and the neutral switched. This allows there to be power at the light fixture when the switch is off.

When you are getting to do this, just check continuity between the single wire at the breaker, or fuse, and the switch, making sure the power is off. good luck.

If there is only one Romex wire (bundled black, white, and bare Cu) entering the electrical box, both the black and white wires are considered 'hot' by convention, best practice would be to mark the white wire with black tape to designate it as part of 'hot' leg of the circuit, the white wire is just being used as a return to the ceiling electrical box. No 'neutral' wire exists in a single gang switch box with only a single Romex wire running to it. Just identify the always hot side (line side) of the circuit by probing both terminals on the original switch with a voltage indicator while the circuit is still energized, connect this wire (after killing power to the circuit of course!)(should be the black one if the original installation was done to code/convention) to the line wire of the dimmer, the other (white wire usually) to the load line of the dimmer, and the bare ground to the green wire or ground screw. Though by the time I finish typing this, I'm sure your lights will already be dimming satisfactorily. Hope this helps, glad to share my perspective as a home depot electrical dept associate and residential electrical DIYer.

Hi Netmaker

The way that I would look at this situation is, you have a light switch on the wall, when you examine this you will find that there are wires connected on either side of the switch, so all you need to do is replace the switch with a switch and dimmer connected in serries.

The explain in more detail choose the wires connected to one side of the existing switch and connect these to the common of the new switch then connect one wire from the dimmer to the one way terminal of the switch. now all you have left to connect is the other wire from the dimmer and the other wire from the switch, just join these together in an insulated terminal.

You may also find that you have some netural connections at the switch, these should be connected to the loop terminal which is the same as connecting them in an insulated terminal.

It is not rocket science, but you have done the right thing by asking.

Cheers Joe

Thank you all again.

I may just take a picture of the old wiring and post it to be sure. I'll be doing several switches with dimmers as in our remodeling this old house, we are using Vapor Tight sealed light fixtures. Nothing to do with vapors in the house, the decor of the house is pine plank floors and walls and a corrugated tin roof sheeting for the ceiling.

We look like a cross between the original Clampett house and the Ponderosa.

The Vapor Tight fixtures ( we call them Tug Boat Lights) throw so much light across the rooms that we need to dim 'em. I like the look, the tight fit and the solid metal case they come in. Fluorescents and such would make more sense in a 'normal' house setting but our shack is nothing BUT normal.

Thank you all again.

NM

I thought you had to have a special type of fan to run a dimmer with it?

Who said anything about running a fan on a dimmer?

A word of warning! I've got dimmers on most of the lights in my house: it's getting more and more difficult to buy light bulbs. The lights without dimmers all have CFL (Compact Fluorescent Lights) which you can buy for about 20p (30 cents) now. But I spent £10 (~$15) on a CFL which was supposed to work with dimmers and it only lasted three days.

I'm probably too late to stop you getting the dimmers, so, if your vapor tights use incandescents, stock up on light bulbs.

Why the heck did someone mark Lyn's post #2 off topic?

OOOoops!

You mean those new 'curly que lights' will NOT hold up to dimming?

Only incadescent lights work with dimmers?

You can get CFLs (curly Qs) that will work with dimmers, but you have to get a special kind. They have them at Lowes or Home Depot.

Yep, takes a "special" CFL to work with a dimmer, and then they really don't "dim" all that much. If you think about how a CFL works, it's not too surprising that you can't dim them very low. The ballast has to develop enough voltage to get the gas to ionize, and if you start dropping that voltage, it's not long before you are back below the threshold of ionizing the gas, and you get NO light.

Beware, the dimmable CFL are had at a premium on the price! I've never gotten any, because I know they won't dim very well, and they are more than twice the price of "regular" CFL's.

Me, I'm waiting on the LED revolution. They've got dedicated IC's coming out that will drive LED's, and play nice with triac dimmers.

Tom D.

As already advised, Be sure to read instructions on the label of the dimmers box. There are dimmers that will Only work with incandescent lights and there those that a little bit expensive that will work with both CFL type or incandescent type of bulbs. Connection - wise they are the same..

If I had known you wanted to use CFL's I would have said something a lot sooner. I would also be cautious about using them in recessed ceiling fixtures. Wikipedia has a good article on CFL's, which down towards the bottom of the article, they talk about using dimmers with CFLs.

I had to give you a GA, as much as it hurts not being able to satisfactorily use a dimmer with CFLs, at least you found out before you invested a whole bunch of money into it and not be happy with the out come. Good Luck and Be Safe!!

Thank you. After finding this site a few years ago, I have learned to bounce any thoughts, ideas or questions through here first. From my business in net design and fisheries to remodeling this hurricane beat-up house.

Where else can you tap into THIS amount of know-how and experience with a few strokes on a key board?

In my business, knowing what NOT to do is just as important as knowing WHAT to do. In two weeks I am heading to Illinois on a fishery job to demonstrate two new prototype nets for capturing Asian Carp. ( This method here is NOT recommended for obvious reasons!).

These two new prototype nets are the culmination of 4 years of research and one failed attempt with a high end trawl gear. The 'failure' showed me where NOT to go....hence I opted for a more passive method and quieter gear.

Point is, that here on CR4 I get to bounce the ideas and such I do NOT have experience ( or limited experience) in.

Once again, thank everyone. The Tug Boat lights give our old shack a unique look in combination with the corrugated tin ceiling. The dimmer switch idea was a thought and after review here..... one that I see might NOT be worth trying.

Thank you all again.

NM