Need 3-way sw help

[stickboy1375]

When doing old work, creative can be mandatory and educational, but if you can KISS is a the way to go.

On romex jobs we always use white as a traveler. Always dead end a 3 way, and only use a three wire between the sitches. Part of KISS.

Box fill can be an issue.... I hardly ever run a 3way from box to box without hitting the first fixture first......

 

[Builder]

I was asked to teach "how to wire three way switches" to a group of High School farm mechanics class a number of years ago, part of the Vocation Agriculture Farm mechanics contest is on electrical wiring and normally they have to wire a light circuit with three way switches as part of the contest, at lest that was the way it was.

I used first of all a display board with knife switches and easily laid out, with a battery to power it,
then made a second board with 3 way switches substituted for the knife switches, so they could see the operation of them,

Then I made up some wood blocks to represent switches, a light fixture, and some wire nuts, and then proceeded to use 1/4" rope, with tape, color coding, on it and bundled as if it was wire,
The blocks had holes drilled in them and color coded around the holes to represent the screw terminals on the switches and the light socket,

and with this they could easily and quickly hook up a circuit, and have it checked by an instructor, and then the position of the switches and the light and where the power was sourced could be changed in seconds and let them "wire" a new circuit.

In a very short time they had all grasped it, and all did good on the electrical section of the contest.
At there annual banquet they invited me to, they gave me a plaque for my willingness to help them prepare for there contests,

 

[RonP]

thanks again for all of help.

 

[hurricaneflyer]

RonP, this probably won't help you but for future searchers I am adding this.

I got frustrated not being able to get helpers/home-owners/contractors to understand how three ways work so I came up with this.

It is a good easy always available free method I use in the field, not as good as Builder's and other methods in a classroom setting, but in the field it can't be beat:

Take a flap of a plain cardboard box.

A couple of inches from the left side of the cardboard flap draw the three terminals of a three way switch. Make sure the common terminal is towards the outside edge of the cardboard and the traveler terminals are towards the inside. The terminals should be about 1 1/2 inches apart or so.

A couple of inches from the right side of the same cardboard flap draw the three terminals of the other three way switch. Make sure the common terminal is towards the outside edge of the cardboard and the traveler terminals are towards the inside. The terminals should be about 1 1/2 inches apart or so.

Draw in the travellers between the switches, the power coming in to one switch, and the switch leg going to the light from the other switch.

From the back side of the cardboard poke a nail or screw or short lenght of wire or something like that through the cardboard where the common terminals are. Lay the whole thing down flat.

The "pointers" on each end can be played with to show how the path of the electricity continues or is interrupted from either switch.

Being able to physically change the position of the "switches" on the cardboard and trace the path in real time, without relying on memory/imagination/previous experience seems to work miracles for most beginners or other interested people.

 

[Brady Electric]

3 way sw

3 way sw

Okay, maybe I'm dense.

When I wire 3-ways and 4-ways, I always use black and red for travellers and white for the neutral.

Why the heck would you use white for a traveller when red and black are perfectly good colors? Or are you talking about wiring a dead-end 3-way? Personally, I try to avoid dead-ends because I hate the box fill that comes from doing it that way.

All you need is travellers from one sw to another if you feed one end hot and the other end from the llight. Thus you just need to run 14/2 and then you mark the white wire red or black because it carries current. Your neutural is at the hot end and you catch the other neutural from the light fixture. Rember you are feeding the light hot. I know it is easier to run it with 3 wire but this is the way old timers did it. I started in 1972 and things have changes alot since them. Not STUPID just seasoned. Semper Fi. Buddy

 

[Brady Electric]

3 way sw

3 way sw

All you need is travellers from one sw to another if you feed one end hot and the other end from the llight. Thus you just need to run 14/2 and then you mark the white wire red or black because it carries current. Your neutural is at the hot end and you catch the other neutural from the light fixture. Rember you are feeding the light hot. I know it is easier to run it with 3 wire but this is the way old timers did it. I started in 1972 and things have changes alot since them. Not STUPID just seasoned. Semper Fi. Buddy

Sorry I spelled remember wrong. Guess I need to preview my message before I send it.( In a hurry). Semper Fi

 

[karl riley]

Whichever way you run a three-way just be aware that unless all parts of the circuit have equal and opposite currents running together you create a huge magnetic field. I know of no way to achieve this with a two-conductor traveler.

How about including this criteria in your lesson to the students? It's so simple.
Karl

 

[bhoang]

The 3-way switch in my house is wiring incorrect. I plan to open it up and re-wiring it. Any suggestions? Thanks.

I have deleted this post, in accordance with the Forum rules. This Forum is intended to assist professional electricians, inspectors, engineers, and other members of the electrical industry in the performance of their job-related tasks. However, if you are not an electrician or an electrical contractor, then we are not permitted to help you perform your own electrical installation work.

-George

 

[growler]

That did it for the bulk of the students however during lab some students still have a problem with the travelers.

Have you tried letting the students that do understand how things work teach the ones that don't. Students communicate with each other better than they communicate with an instructor.

 

[ptonsparky]

Have you tried letting the students that do understand how things work teach the ones that don't. Students communicate with each other better than they communicate with an instructor.

There is also no better way to learn than having to teach someone else. It will help both students.

 

[LarryFine]

Just to point out the proper way of using the white in either 2- or 3-condcutor cables: Of course, when the fixture is at the end of the run, the neutral will be the white wire from switch to switch (to switch, if a 4-way is involved).

If you feed the fixture box with the hot and neutral, naturally the incoming neutral goes directly to the fixture. The incoming hot should connect to the white in the 2-conductor cable running to the first 3-way switch box, just as with a single-pole switch loop.

However, that white wire should connect to the white wire in the 3-conductor cable to the second 3-way switch, and through any 4-way's in between. In other words, always run the hot on the white all the way to the common terminal of the farthest switch.

Then, the red and black are the travelers returning from the last 3-way, through any 4-ways, to the first 3-way, and finally back to the fixture on the black wire in the 2-conductor cable, again just as with a single-pole switch loop.

This is explained in 200.7(B)(2) ('02 NEC). While the requirement to re-color this conductor may be new in the '02 NEC, the requirement that the white be used as the supply, but not travelers or return leg, has been the same for a long time.

The one case where it is unavoidable to use a white as a traveler is when both 3-ways are fed from the fixture box via 3-conductor cables. Even then, the white in the first 3-way run would be the feed, red and black would be the travelers, becoming red and white to the second 3-way, with the return leg as the black.

That means the traveler pairs meet up in the crowded fixture box, where the color mis-matching occurs. If I have my choice of coloring, I like blue over red or black. However, if the white will become black, I like using the two blacks as travelers, leaving the red as the return to the fixture.

The bottom line is that you cannot always count on conductor color remaining constant throuought a switching scheme, except in conduit, where you get to choose the colors, and there is no excuse for using a white as a hot. Even with NM, there is the possibility of an intervening junction box somewhere.

If you're replacing 3-way switches, it's best to tag the wire on the common terminal if there is the slightest possibility of losing track. In the case of 4-ways, it's easy to forget that the two dark terminals connect to the two travelers from one 3-way and not to the two blacks, one from each 3-way.

 

[iwire]

However, that white wire should connect to the white wire in the 3-conductor cable to the second 3-way switch, and through any 4-way's in between. In other words, always run the hot on the white all the way to the common terminal of the farthest switch.

Larry that is how I would do it but I don't believe the NEC requires that.

The only requirement is that the white is used for the supply to the switch but not as a return conductor from the switch to the switched outlet.

That 'switch' could be at either end of a group of three ways or four ways.

So basically as long as you get the 'hot' back to the fixture itself not using the white you have meet the code requirement.

 

[hardworkingstiff]

Larry that is how I would do it but I don't believe the NEC requires that.

The only requirement is that the white is used for the supply to the switch but not as a return conductor from the switch to the switched outlet.

That 'switch' could be at either end of a group of three ways or four ways.

So basically as long as you get the 'hot' back to the fixture itself not using the white you have meet the code requirement.

So it's not possible to wire to the NEC two 3-ways where the feed is in the switched outlet and a 3-wire goes to each of the 3-ways. One of the 3-wire white conductors will be either a traveler or a switch leg.

 

[macmikeman]

Larry that is how I would do it but I don't believe the NEC requires that.

The only requirement is that the white is used for the supply to the switch but not as a return conductor from the switch to the switched outlet.

That 'switch' could be at either end of a group of three ways or four ways.

So basically as long as you get the 'hot' back to the fixture itself not using the white you have meet the code requirement.

For what it's worth thats how I see it also.

 

[Dennis Alwon]

So it's not possible to wire to the NEC two 3-ways where the feed is in the switched outlet and a 3-wire goes to each of the 3-ways. One of the 3-wire white conductors will be either a traveler or a switch leg.

Sure you could but you couldn't make the white wire the return to the fixture.
Just slice the whites and then splice the reds. One black would be a fed the other would be the return. Leave the whites as travellers.

 

[hardworkingstiff]

Sure you could but you couldn't make the white wire the return to the fixture.
Just slice the whites and then splice the reds. One black would be a fed the other would be the return. Leave the whites as travellers.

Ok, but now we have to reidentify the white, right?

200.7(C)(2)

 

[chateau mike]

break one open so they can see how it works

 

[Limey Pete]

2way/3way

2way/3way

Hi. I'm one hour old on this forum, hope I'm not speaking out of place but I'd suggest: Start by explaining it is a 2 way switch, whoever came up with 3 way?. Then try drawing a circuit diagram with the hot and neutral going to one each of the travellers and the lamp between the common of each switch. It WILL work! of course you'll need to explain how this is not the right way to do things, but it's the way I figured it out many years ago when left to my own devices to come up with a two(three) way switch design at college. and I think it is clearer to visualize.

 

[480sparky]

I learned 3-ways and 4-ways from an instruction who gave use three things:
1. a sheet of paper
2. a pencil
3. a meter

Give the people that and make them figure it out themselves.

 

[LarryFine]

Start by explaining it is a 2 way switch, whoever came up with 3 way?

Do that, and they'll have trouble buying them.

Then try drawing a circuit diagram with the hot and neutral going to one each of the travellers and the lamp between the common of each switch.

I wouldn't.

. . . it's the way I figured it out many years ago when left to my own devices to come up with a two(three) way switch design at college.

And that's why.