A note on the Featured Image, the Image at the Top of the Post. These are both 3 Way Switches. Yes, I know, they’re different from each other. Tacky, right? The Clear Switch controls the light in the immediate area of the Switch. Upstairs, they’re both illuminated, downstairs just one of the two. I have a post on illuminated Switches on this blog, written for the fun of it, give it a peek.
OK, who named them?
3 Way Switches. There’s 2 of them. Add a 4 way switch, then there’s 3 of them. That makes sense, Not!
OMG, I found the answer, I love researching posts for this reason:
Understanding 3 Way Wall Switches:
The term refers to the fact that there are “three different ways the switch toggles can be arranged: both toggle levers up, both toggle levers down, or the toggle levers in opposite positions.”
- So, I made an Animation of Two Three Way Switches, Controlling a Single Light Bulb, from an AC Source.
- Then, a Second Animation of the above switches, with a 4 Way Switch Added to the Action.
- Lastly, the scenario directly above, with two more 4 Way Switches added.
In the drawing immediately above, the Down Arrows point towards the 4 Way Switch Locations, the Up Arrows Point Towards the 3 Way Switch Locations.
In Basic Lighting Wiring, the system uses 2 wires with a Ground, i.e. Hot, Neutral, and Ground and there are several ways to run the wiring. Yet despite how the wiring is run, the Switch must interrupt the Hot Wire so when the Switch is Off, there is no power at the Light Socket.
With 3 Way Wiring, the Wires that Run from One 3 Way Switch, to the Other, are called Travelers, there are Two Travelers Shown on the Top of each animation. The Light Needs a Neutral, and that is Depicted on the Bottom of Each Animation.
4 Way Switches just Reverses the Traveler Wires Coming into it.
The Above Link shows the Practical Aspects of Wiring these Switches. Power can be fed a few different ways. The comments rightfully point out the 2nd Drawing is labeled incorrectly, the Leftmost and Rightmost Switches are 3 Way, not 4 Way. But it’s a nice series of drawings.
And, Color Coding of Wires, this doesn’t mean these colors are what your house uses, goodness only knows what you’ll find that others have done in the past. An Electrical Tester and Extreme Care are needed, and thoroughly testing all points for Energized Wires is a MUST. The above, though, is provided in case you do, or an Electrician Does, new work.
The worst shock of my 25 Year Electrical Career came in this home, after I retired. Two Lighting Switches in one Box, I knew one was hot, the other was deenergized, I turned-off the Breaker to work on it, but wanted the hallway light on. The switch wouldn’t go back into the box easily due to the inflexible solid conductors. I reached in while holding the switch in my right hand, and the switch was grounded, and I accidentally touched the hot wire on the other switch with my left hand. Bam! Right Across the Center of my Chest. The worst scenario. I screamed and pulled away. Dang it hurt. Use a Headlamp, don’t take chances around Hot Work, SHUT OFF THE BREAKERS AND TEST FOR A DEENERGIZED CONDITION!
It appears that Two 3 Way Switches is the limit, but any number of 4 Way Switches can be added to a 3 Way Switch set-up. Son of a gun, learn something new every day.
A home we inherited, and the home we bought with the money from selling the home we inherited (though we lived there for more than 15 years), were rewired by Residential Electricians. Both Homes only had:
- One switch at the top of the steps for the light at the top of the steps.
- One switch at the bottom of the steps for the light at the bottom of the steps.
So, you’re going to bed for the night, turned off all the lights downstairs, and the stairs are dark, hmmm. Well, why not turn on the light at the bottom of the stairs? Because when you get to the top, you can’t turn it off. Conversely coming down in the dark, if you turn on the upstairs light with a switch upstairs, you can’t turn it off once you get downstairs.
One more thing I discovered, you can have a nervous breakdown researching this stuff.
- One site says you need a light at the top and bottom, each with a switch near it, but that Three Ways Switches are not specified by the National Electrical Code (NEC), just a switch at each location. Not too bright, figuratively, and literally, of the NEC.
On another site, a man preparing to have a home rewired was told by the Electrician that Electronic Switches are not permitted, that the NEC Requires Hard Wired 3 Way Switches. But commenters offered these:
- Exception to (a), (b), and (c): In hallways, stairways, and outdoor entrances, remote, central, or automatic control of lighting shall be permitted.
- 210.70 (A) (1) Exception No. 2: “Lighting outlets shall be permitted to be controlled by occupancy sensors that are (1) in addition to wall switches or (2) located at a customary wall switch location and equipped with a manual override that will allow the sensor to function as a wall switch.”
This second part immediately above is for switches that turn on Automatically as you approach or enter a room, I’ve seen them in restrooms in buildings, you walk in and the light comes on. These aren’t particularly good for the Upstairs/Downstairs and Stair Lighting, but it does reaffirm the NECs acceptance of Electronic Switching in their code.
So, it appears that if you have that Switch Downstairs, and Switch Upstairs, next to the their corresponding Switches, with the Marvel of Modern Electronics, there is likely a solution that doesn’t involve new wiring AND is NEC Compliant, some can probably be installed by people familiar with Safety around Electricity and that possess Basic Mechanical Skills and Tools.
In both homes, during the rewiring, both groups of Electricians tried to get me not to have a 3 Way Switch at the Top and Bottom of the Stairs, but I said it was a must, and there was no argument on their part, just hoping I’d give in but I didn’t. It’s so nice to control both lights each from one location. Even though I now see that Electronic Devices can be used to control the lights from both locations, during a re-wiring or new home build, 3 Way Wiring and Switches should be installed.