There are two abnormal and rare 3-way systems that may be encountered. They’re called by various names (California, Hollywood, coast, farmer’s, French, Chicago, Carter, lazy Susan, lazy neutral). The names are confused between the two kinds. One is illegal and presents possible shock danger. The other (British, I think) seems allowed by code and is so different in its concept that few electricians here would even recognize it. What I’m saying about 3-way systems just isn’t meant to apply to either of these. Basically, the illegal one attaches a hot permanently to one traveler and a neutral to the other; the commons each extend from their terminals to the sunshine fixture. The legal one likewise attaches a hot to 1 traveler but the leg (to the light) to the opposite; another wire runs between the common terminals. Here is a diagram of these Rare 3-ways.
Since there’s a wide number of ways in which multi-switch systems are wired in practice, I give, below, quite a lot of 3-way and 4-way switch diagrams, so you possibly can perhaps recognize your individual version. To see some 3-ways in the context of an entire circuit, see the standard circuit.
Wire Colors in a Multiple Switch System
I will try to describe here what color the insulation on the wires of multiple-switch systems will commonly be, if they aren’t miswired. Lately, Code is wanting any “factory” whites serving as travelers or as the hot-end hot to be re-marked black or red. Here I am only telling what you will commonly find in most homes. The new wire on the common terminal of the new-end switch might be black (or rarely: red or white). The sunshine-leg wire on the common terminal of the leg-end switch will likely be black or (rarely) red. Each traveler pair is contained in a single cable, and will likely be either black and white, black and red, or red and white. Most other white wires present in these switch boxes are neutrals which can be connected to one another and not to any of the switch terminals. Any bare or green wires are grounding wires connected to one another. If the switch has an additional green screw, to fulfill Code a bare piece should be run to it from all of the grounds.
The basic 3-way Switch Arrangement
Normally encountered 3-way systems (3-way “circuits,” as some call them) all share one scheme-theme:
— S === S — O
3-way Switch Variations
A. Here the hot arrives at one switch box. It may then be connected through to the other switch to be its hot-all-the-time common, or instead it will possibly attach as common of the switch where it arrived to start with. Either way, the travelers between the switches find yourself giving hotness or unhotness to the light “leg.” This leg either comes directly off the common of the switch nearest (electrically) to the light, or is tied through to the light from the switch furthest from it. This arrangement is a standard one.
B. Here the hot for the system arrives at the sunshine box, but its functional connection is at whichever switch it’s connected through to. The other switch finally ends up sending the choice of the travelers back by way of the same cable that brought hotness down from the light box.
C. Here the travelers from one switch to the opposite are simply routed through the light box, where connectors pass them on through.
– The fact that house-cable comes with either two or three insulated conductors
– The physical relation (direction, order, distance) among the many switches and lights
– The available sizes of electrical boxes to carry the wires, lights, and switches
– The direction from which the circuit is approaching the world
– The Code restrictions on how the cabling can be done
– The electrician’s preferred tradition
The basic 4-way Switch Arrangement
Normally encountered 4-way switch systems all share this scheme-theme:
— S === S === S — O
where the “S”s, the “O”, and the lines are as described above. Here then are two ways you might see this basic scheme, complete with neutrals, boxes, and cables:
4-way Switch Variations
As you possibly can see, this picture corresponds to the diagram for the basic 3-way switch system above. Many variations of this basic theme are possible. For instance, the three-way switch schemes (A, B, C above) will allow a 4-way switch and box (or any variety of them) to be interposed between the three-way switch boxes. Then all three switches will work the light(s). Remember, one 3-way switch needs a constant hot, the other must be able to “heat up” a wire to the light, a neutral needs to achieve the sunshine, and two travelers must be passed between each switch in succession. Without taking on too much space, here are a number of 4-way schemes in very simplified form, inspired by A, B, and C above:
— S === S === S
— O === S === S === S
— S === S === O === S
— S === O === S === S
— O === S === S
Next, for example of more possibilities, I show a 4-way system in which the new wire enters at the 4-way switch’s box:
You probably have begun to understand the thought of 4-ways, you could also be getting the impression that you would invent your personal approach to wire such a system. It is true. Whatever works, is not against Code, and is safe is feasible. This site is not to advise you about design, Code, or installation.
3 way Switch Troubleshooting
– One of the switches itself can fail.
– The connection of a wire at one of many switches can become loose. Both this and the previous problem can often be checked without disconnecting anything. With one prong of a neon tester in your hand, touch the other prong to the common terminal of each three way switch in turn. If a kind of lights the tester up (is hot) regardless of all possible switch-positions of both switches, that is the hot end. Then just follow whether the next switch (even if it is a 4-way) is passing this hotness on through as expected, based on the diagrams above. Wherever it does not pass through is the bad connection or bad switch.
– Someone replacing a switch can accomplish that incorrectly or can install a switch that only has two (non-green) terminals. Replacing a toggle-handle style switch with a big decorator style “rocker” switch may invite an issue. The placement of the terminals on the rocker is sort of different. Here the foolproof way to attach is to have the travelers attach to the two same-color screws, and use the remaining common screw for the other wire.
– The 2 travelers are in the same cable with each other.
– Any pair of switch screws (or dimmer’s wires) that are the same color as each other are for a traveler pair. Leviton’s instructions for his or her rocker-style 4 way switch will confuse people by how they call one pair of terminals “IN” and one pair “OUT”; they’ve these identified backwards, however it does not even matter.
– The only wire in a multiple-switch system that is hot all the time when all of the switches of the system are disconnected from their wires, is the recent. It would attach to the common terminal of the “hot end” switch.