Is there an electrician in the house?

Recently, we bought a new (pre-existing) house with a large, rectangular living room. The living room has recessed lighting controlled by “3-way” switches at opposite ends of the room. In other words, one can turn the lights on and off from either switch.

The problem is that I want to install dimmer switches. The lights are great for entertaining, but are too bright for “home theater” TV watching, and other intimate activities (quit snickering in the back, boys). I want to retain their brightness, but I would like to dim them on occasion. Does anyone make a “3-way” dimmer switch? Do you know any way I could dim the lights and still retain the “3-way” flexibility? If I wanted to eliminate one set of switches, could I just take the switch out and connect the wires directly to each other (with no switch in between)? Then, I would have regular dimmer switches at the other end. Would that work?

Thanks. Gee, home-ownership is fun!

If I understand the question, you can replace teh current switches with a dimmer. THey are the same as a regular switch in terms of wiring.

Three way switches are not regular switches. I think you would need a special dimmer switch.

Mr.Zambezi, that is not so. You can replace simple on/off switches with dimmers but two way switches are wired differently and cannot be replaced with a simple dimmer.

I believe you can get dimmers with remote control which may be a way to solve this.

There is such an animal. Check your friendly neighborhood hardware store. Or Home Depot. Or Menards. Or probably even Wal-Mart.

It is a common item.

Delta-9, former hardware store manager-


Not only do they make dimmers for three-way switches, but if you’re a real couch potato like myself, you can buy a setup that contains one “intelligent switch” and one remote switch so that you can dim the lights from either end of the circuit. It’s quite a bit more expensive ($45.00 vs. $18.00), but what price gadgetry?

Heck, if you’re really lazy, they even make remote controlled dimmers.

At our previous house I installed a living room light and 3-way switches. Like you, I really wanted 3-way dimmers, and tried to figure out a way to do it.

I went down to Sears Hardware and checked out my options. To my surprise, they sold a dimmer (Leviton?) that claimed to be “3-way.” Being an electrical-kind-of-guy, I couldn’t figure out in my mind how it would even work - it seemed impossible using conventional / low-tech methods. As a research endeavor, I bought two of them and made a mock-up in my workshop. Just as I suspected, they did not behave as you would think a “3-way dimmer” would behave. I forget exactly how it did behave, but it was more-or-less a “pseudo 3-way dimmer.”

Anyway, I scrapped the idea of trying to put in a 3-way dimmer and instead put in two 3-way switches one (normal) dimmer. The dimmer was next to one of the switches. Worked like a champ!

Coincidentally, I have that exact setup in my house, and this morning, the electrician replaced one of the switches. The parts are common enough that the electrician had it in his truck in the right color.

Another thing to check before putting in a dimmer switch – know whether or not the bulbs running off of it are halogen. Doesn’t sound like they are, but make sure. If the lighting system is low-voltage, they almost certainly are, so that’s one way to know.

The problem with running a halogen bulb at a lower light level is that it needs to be on at full brightness for the filament to regenerate. If it doesn’t get this, the light bulb will definitely not last as long as specified, which ends up being less economical for you (since the bulbs are more expensive). Note that there is no problem with running a halogen light bulb at low levels, just don’t expect it to last as long.

And based on what Crafter_Man said, and the description quoted by Delta-9, I’d guess you will probably only have the dimmer control on one side, with the other side being on-off only, unless you go with Finagle’s system.

A dimmer can only be in one place so if you want to control it remotely you need a remote control which can be wired or wireless.

A two location circuit is wired like this:

W-------X-------/                           \-------
                 --------------------------         |
110V                                                |

Where X is the light. Then the switch switches between two wires. If the other switch is on the same wire, you have continuity, if it is on a different wire, no continuity. In this circuit you can insert a regular dimmer anywhere along the single wire and it will work separately from the switches. But if you want to control the dimmer remotely, then you need the special kind.

I guess I am wrong. I have not seen a 3 way switch in my remodeling days. Exactly how are they different?

A regular one is not really a switch but an interruptor as it either opens or closes the circuit. A 3way is a switch because it switches the input between two outputs. In reality you can use a 3 way as a regular interruptor but not the other way so it could well be that they are all switches even if they are used as interruptors. But a dimmer can replace an interruptor but not a switch.

As is often the case with these things How stuff works has a good page on it. Not much to say about dimmer switches but a good description of how a three way switch works and how it is different than a normal switch.

Yes, IAAE. A traditional “3-way dimmer” switche only dims at one side of the circuit, while you can turn them one or off at both sides.

As mentioned, newer “smart” dimmers can dim the lights from either end of the circuit. They can send a signal through your wiring to the other dimmer to let it know where they are “set”. In this manner, you get the best of both worlds. The downfall is the cost. Not only will they be much more expensive, but you will have to buy two, as opposed just one of the other setup.

Yes, you can just remove one three way switch, and use a dimmer on the other side. You will have to find the right wires to wire nut together, but you will essentially pass through straight through where one switch was and use the other as your dimmer.

Don’t die. Turn off the circuit before messing around, and have someone else at home, just in case.

So, if I’m following this correctly:

Install a special 3-way dimmer in one location and leave the other location alone. Then, I can dim the lights (at the one location) and simply turn them on and off at the other location. I assume at the on/off switch, the lights will turn on to whatever brightness the dimmer is set for. This setup would work fine for me – I don’t need the dimmer control at both ends of the room. The remote control would be cool though – the lights dim as the THX logo blasts away through the speakers. Gives me shivers.

I’m a little concerned about what I’ll find when I open the switch box. I’ve replaced regular on/off switches, but I’ve never messed with a 3-way. Hi ho, hi ho, it’s off to Home Depot I go.


You have it right.

Buy the dimmer rated for the kind of lights (halogen/incandescent) you have. The box will be labeled. Add up the wattages of all the lights. This is the “load”. The dimmer will be rated (e.g., 650 Watts; 800 Watts, etc.) and must exceed the load.

When you remove the old 3-way:
Note the wire/screw combinations on the old switch.
One screw will be a different color from the other 2. This is the common.
The new dimmer will probably not have screws, but will have 3 wires coming out of it (plus a green or bare ground, maybe). Buy appropriate-sized wire nuts (probably yellow) to connect them to the wires in the switch box.
One wire on the new dimmer will be the common according to the diagram which comes with it. Make sure this is the one you connect to the wire which was connected to the common screw on the old switch. The other 2 wires in the switch box can be connected to either of the other wires on the dimmer.

Happy lighting.


And as I’m sure you’re already aware, we have names for the different switch configurations:

Single Pole Single Throw (SPST) : Simple interrupter. Two connections. Used as “one-way” switches for household lighting.

Single Pole Double Throw (SPDT) : An actual switch as defined by Sailor. Three connections: one common and two legs. Called a “three-way” switch when used for household lighting.

Double Pole Single Throw (DPST) : Two electrically-isolated SPST switches ganged together via a mechanical mechanism. Four connections.

Double Pole Double Throw (DPDT) : Two electrically-isolated SPDT switches ganged together via a mechanical mechanism. Six connections.

(I don’t believe the last two configurations are commonly used in household wiring.)

I’ve heard this theory before, but it doesn’t match up with my experience at all. (For those who don’t know, the fill gas in a halogen bulb is supposed to cause vaporized metal from the filament to re-deposit back onto the filament itself instead of all over the inside of the glass. Consequently, the bulb can be designed to run the filament hotter, giving a brighter, more efficient light, the filament lasts longer, and the bulb stays nice and bright throughout it’s extended life. But the re-depositing action doesn’t happen unless the bulb gets very hot, for some reason.)

I’ve got three halogen lamps at home, all with dimmers. One of them I bought used, complete with used bulb, about three years ago. The others are far older - about 12 years old, perhaps. All of these lamps are used, on average, for several hours each day, mostly with the dimmer set for less than full power.

So the obvious punch line: I have never had to replace a bulb in any of these lamps. I’m pretty sure they’ve lasted a lot longer than the meager (compared to say, fluorescents) 2000 hours or so that’s standard on most halogen bulbs. None of the bulbs are special “long life” bulbs, to my knowledge.

I’m sure a light-bulb designer would have a better explanation than I would. But I’ve got a guess: although the lower temperature may hinder the re-depositing action, it’s more than offset by an accompanying reduction in metal vaporization in the first place.

X10 makes 3-way switches that can be turned on and off from two or more different locations (replacing originally-wired regular 3-way switches). They can also be turned on and off and dimmed remotely, using any of several different remote controls that can be plugged in anywhere, or a wireless remote control. They are sold under many different brand names. Some of them also offer local dimming from any of the wired locations (that is, without having to use a remote). There are also instructions that can be bought for converting the cheaper models, that don’t support local dimming, into ones that do. I have done the conversions and replaced regular 3-way switches in my house, and they work well. A pair of the switches without local dimming can be bought for less than $20. The conversion costs nothing except some time and a little expertise with a soldering iron. I paid about $10-$20 for the conversion plans. The switches that come with local dimming cost more, maybe $40-$50 for a pair. Most X10 equipment can frequently be found heavily discounted.