Replies

1. 
   JohnSprung2 | Dec 02, 2009 12:57am | #1

   This is way more than a normal voltage drop, and unlikely to be due to the length of the run.  Like nobody has a house that big.  Almost certainly you have some resistance in a connection somewhere, maybe a worn-out switch, a loose screw holding a wire to a device, a bad splice....  Wherever this bad contact is, it's making heat, which is dangerous.  You need to find and correct this. 

   The best idea is to do a whole-house electrical system tune-up.  This might be the worst thing, but probably not the only thing that's wrong.  Start bright and early on a Saturday morning, turn everything off, open every box, clean and tighten all the splices, replace any worn out switches, receptacles, and light fixtures.  Electrical is one place where it's so much easier just to go through and make everything right than it is to find the things that go wrong as they crop up.  If you have a whole bunch of enthusiasm for this, while you're at it, you might also draw up a rough plan of the house, and identify on the plan which circuit breakers control what.  That'll save you some time and money if you need to call an electrician. 

   If you still have the problem after a whole house tune up, then you might have a buried box or something. 

    

   -- J.S.

    

2. 
   brucet9 | Dec 02, 2009 01:07am | #2

   If the three-way switch you intend to pull power from is connected directly to a hot circuit (ie: it is first in line), the black screw terminal (common) will always test at 120V between it and ground or neutral no matter what position the switch is in.

   If, as I suspect, the three-way you are testing is at the load end of a three-way circuit, it's common terminal sees power when the switch is in one position and does not when the switch is in the other position.

   The 94V reading you saw (digital volt meter, right?) with the switch in one position was likely a phantom voltage reading on what is essentially a dead line; the traveler that is not connected to power at the other switch. If you were to put a small light bulb like a night light in series with your probes while testing, the voltage would read zero.

   What this all means to your project, is that you can't take power from that receptacle unless you disable one of your three-way switches and wire one of the travelers (the red or black) directly to the hot wire in the box where the other 3-way is installed and use it as hot for your new circuit. Then either of the remaining 3-way switches can be wired to control the light, but one of them will have to be removed.
   BruceT

   Edited 12/1/2009 5:08 pm by brucet9 <!-- BRUCET91 -->

   
   

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   Edited 12/1/2009 5:14 pm by brucet9

1. 
   michael2160 | Dec 02, 2009 02:36am | #3

   Great responses. I have an outlet nearby that I will use for the new switch leg.

   Michael

1. 
   brucet9 | Dec 02, 2009 03:59am | #4

   Are you there?If Michael takes power for the switch to his new light fixtures off an outlet, should he use 12ga wire if that's what the outlet is wired with? It would seem to me not a good idea to run 14ga to extend a circuit that's protected by a 20A breaker.What do you think?BruceT

1. 
   JohnSprung2 | Dec 02, 2009 04:11am | #6

   Yup.  If the breaker's a 20 the wire needs to be 12 or better.  If the breaker's a 15, then you can use 14. 

    

   -- J.S.

    

2. 
   renosteinke | Dec 02, 2009 04:11am | #7

   I couldn't agree more ...

   For the ordinary circuit, EVERY wire protected by a 20-amp breaker ought to be at least #12. I care not that it goes to a switch, or just powers one light, etc.

   Likewisw, once you find ANY #14 wire on a circuit, the breaker ought to be no larger than 15-amp.

   You can use larger wire if you're worried about voltage drop, etc., .... but not smaller.

   Getting back to your original question, though ...

   Meters can give false readings, and often switches will let a tiny amount of current through even when in the 'off' position. I don't think you're reading voltage drop at all; I think your meter is lying.

   You mentioned this was a 3-way switch. What you need to do is -first- determine if the 3-ways are wired legally. That is, the circuit drawing would look like this:

   Power-> 1st switch-> 2nd switch-> lights.  If the bits are in any other sequence, we have a problem.

   You need to identify which switch is the first one; then toy need to tie into the hot and the neutral before they get to the switch in order to power these other lights separately from the 3-way arrangement.

   Hope that helps.

    

   Edited 12/1/2009 8:17 pm ET by renosteinke

3. 
   DanH | Dec 02, 2009 04:07am | #5

   You can't get power from a 3-way switch unless you're very lucky. (And if you don't understand why I said that you should keep your fingers out of there.)

   This country will not be a permanently good place for any of us to live in unless we make it a reasonably good place for all of us to live in.  --Theodore Roosevelt