4-way switching

[CoolWill]

But on all of them, regardless of the screw orientation, the black screws are one set of travelers and the brass screws are the other.

 

[LarryFine]

Some 4 ways wire differently than others. On some the travelers are on the sides and others they are across from each other.

See post #12.

 

[Strathead]

I wired in a huge house for a gadget nut . House had 5 separate entrances and several cross over hallways or walkways. Ended up with over a dozen four way switches. The great electrician working with me never wired in a four way switch so showed him how but he still wired some wrong. I always found it easier to wire in or replace four way switches if they used a NM cable from or to the three way switches or in cases of more then one four way. Customer asked for just two switches to turn on outdoor flood lights but added three four ways to be able to turn lights on at any of the five entrances and next to his bed. Like another person stated four way switches are installed between two three way switches. We had a sparky who.loved pulling pranks so I placed a Hubbell two pole switches in the boxes that had Hubbell four way switches. Had the apprentice ask him if he needed any help replacing them . Nope. After he pulled out his hair for awhile we had the apprentice quickly change them.out and tell him he only had to move two wires in each four way switch. My dad had me wire in a four way switch to reverse trains when I was maybe 10 years old.

As long as they use 14-3 or 12-3 romex.

 

[Strathead]

That's true logically (at a schematic level), but once you introduce physical enclosures, there are multiple ways to route the cables.

Say we have two switch locations (initially considered equivalent for counting purposes) and one lighting location, and we're going to wire it up without power passing through to further loads, and without surplus cables. Then we can either bring power to the light or to a switch.

If we bring the power to the light, then we need a cable from the light to a switch (they are equivalent, so only one choice here). The other switch can connect to the light or to the switch already connected. So 2 possibilities here.

If we bring power to a switch, then one option is connect from there to the light. The final switch can connect either to the switch with power or to the light. So 2 possibilities here.

Or with power to a switch, the other option is to go directly to the other switch. Then the light can be connected to either the switch with power, or to the other switch. But the configuration with the light connected to the switch with power was already counted. So just one new possibility here.

That makes a total of 5 ways to do the wiring, when you consider the switch locations initially equivalent.

Cheers, Wayne

I contend that routing the cables and wiring the switches are two different things.

 

[LarryFine]

I contend that routing the cables and wiring the switches are two different things.

Absolutely. In my house, the basement has two main rooms, connected together by a hall in the front with a downstairs front door and the stairs going up, and by a hall in the back with a bathroom and two closets, one of which now houses my home theater equipment stack.

Each room only had a switch by the door to the front hall; one was already a 3-way because of a side door to the outside. The need for a switch by each room's door to the rear hall became apparent, so I decided to convert one to 3-ways, and add a 4-way to the other one.

The 3-way was easy: run a 14-3 to the new switch, feed on the white, return on the black and red. The other room happened to have a J-box in the wring, so I only needed to interrupt the travelers and add a pair of 14-2s to the new switch location. (No, I didn't color the whites)

 

[wwhitney]

I contend that routing the cables and wiring the switches are two different things.

Depends on what you mean by "wiring". If you mean logically or schematically, sure I agree.

But for the sense of "in each switch box, choosing which wire from which cable goes to which terminal on the switch," then that's going to depend on which of the 5 ways (if I counted correctly) you've chosen to run the cables to interconnect the 3 boxes.

Cheers, Wayne