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# Wall Switch (3 way)

#1
11-12-01, 04:25 AM
Mike Pender
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Replaced 2 wall switches that control the same light. I turned the light on from the first switch the light goes on. I shut the light of from the second switch and the light goes out. The problem is you can not turn the light back on with the first switch.

Any suggestions on how to fix.

Thanks.

#2
11-12-01, 05:46 AM
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Here's my guess. It's just a guess. But it's probably a pretty good guess.

I'm guessing that the only reason you changed the switches is to change the color. True or not?

I'm guessing that you reconnected the wires by position on the switch, e.g., you connected the wire that was on the upper left of the old switch to the upper left of the new switch. The problem is that this is not a reliable algorithm, since the upper left screw does not serve the same purpose on different switches. Rather you must identify the "common" screw on both switches.

If you still have the old switches, the solution should be easy. Look at the old switches, and find the "common" screw. It will be the one that is a different color than the other screws (ignoring the green screw). Now do the same for the new switches. Make sure that the same wire that was connected to the "common" on the old switch is connected to the "common" on the new switch.

By the way, use the screws. Do not use the push-in connectors on the back of the switch.

#3
11-12-01, 06:00 AM
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3-way switch circuit

Mike,

There are two possibilities:

--you have the wrong kind of switche(s), or
--you connected the wires to the switches incorrectly.

(I guess there's a third possiblity, wrong switches and wrong connections...but let's not go there right now).

O.K., switches first. Take a look at the switches. You need what are callled three-way switches (even though they control the light from two locations). How to tell if that's what you 've got? Well, a 3-way switch will have four terminal screws: one black, two brass, and one green. Sometimes there isn't a green screw. A standard switch (called single pole, single throw) will have three terminal screws, two brass and one green (again, sometimes no green).

Hint: if you thought you bought the right switch, you might have picked the right box, but with the wrong kind of switch in the box. It happens a lot in the big box stores.

Now for the connections. If you connected the new switches JUST LIKE the old ones, that may be your problem. Switches from different manufacturers have the terminals arranged differently. So if you put the wires in the same places, that isn't necessarily correct.

I need more info on how many and what color of wires you disconnected from the old switches, to guide you through the connections. There are several different ways to run the wire for a 3-way light circuit, and the connections are made differently in each case. No big deal, I just have to know what you have, and the kind of wires previously hoooked to the switches will tell me (if the wiring was done using normal conventions).

Here's a hint: At each switch, you'll see a pair of wires (red & black) that come from the same cable (look way in the back of the box with a good light. There will be a white wire too, but that's not important for our purposes). These two--the red and the black from the one cable--are usually connected to the brass screws (one to each screw, it doesn't matter which to which). The odd (single) black wire at each switch goes on the black terminal. If one of the switches had a white wire (maybe with some black tape on it) attached to it before, that one goes on the black terminal.

O.K., now if you want to know what's going on with the circuit arrangements, search this site for "3-way". There are some nice diagrams (or links to diagrams) of this type of circuit.

Remember to cut the power and VERIFY this with a tester that you've just checked on a live circuit before you open up any electrical box. You already know that, just a reminder.

Work safe.

Cliff

#4
11-12-01, 06:43 AM
Mike Pender
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Hi,
I'm using 3-way switches for aluminum wiring. There are not any different screw colors. The screws are all silver. My house was built before 1950. I also have knob and tube wiring. This probably makes things more difficult.

Any other suggestions?

#5
11-12-01, 07:21 AM
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Look at the lever on your switches. Does it say "on" and "off", or is the lever blank?

Then look closely at the plastic case. Use your reading glasses. Can you find the characters "COM" or "COMMON" anywhere on the back or sides of the case?

#6
11-12-01, 07:38 AM
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All is not lost...

Mike,

Ja, this does mean a little more work.

As John said, the new switches will have one of the terminals marked "commom" or some variation. That is the black terminal I was referring to.

The easiest way to dope this out is to get a continuity tester and a long test lead, and figure out which wires run from switch to switch. Those go on the "non-common" terminals. The other wire at each switch goes on the common terminal.

If you're not clear on how to test for continuity, perhaps the best thing would be for you to get a how-to book in electrical wiring and read up. This isn't rocket science by a long shot, but there are a lot of points that have to be covered and many books do a very nice job. And besides, there'll certainly be other times when you'll benefit from having a home wiring book on hand (like swatting flies?)

#7
11-12-01, 03:32 PM
Wgoodrich
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I think all replies are trying to say about the same thing. The problem is your wiring most likely have no conductors that are of different colors.

You new switches should have three screws per switch. If this is true and you truly have knob and tube wiring you just need to find which wires are the common wire.

This is a case of remembering wiring styles. It may not be correct but if your lucky it may solve your problem. The correct way to find the wiring combination is as said in previous replies by using a voltage tester.

In the switch box you might be lucky and find two wires that come into the switch box and go directly to the switch and one wire that comes from a junction in the box like a wire nut only soldered and taped. The wire that is pigtailed inside the box to other conductors is most likely the wire you need to connect to the black screw of the new switch. This first box should be a good chance to be right.

In the second switch you should find two wires coming in together that should be the two travelers and you should find a single wire coming in by itself. This wire should be the common wire that connect to that black screw. This is a maybe that may be right.

If the above does not work the switches right try a rotation of the conductors in the switch that does not have a pigtail going to the switch but each wire coming in separately.

Maybe a chance it will work

Good Luck

Wg