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Confused about what I'm seeing (switch wires) and what to do/how to test?

Confused about what I'm seeing (switch wires) and what to do/how to test?

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  #1  
Old 07-09-13, 12:55 PM
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Confused about what I'm seeing (switch wires) and what to do/how to test?

You guys (DIY forum) have saved my life before and might literally be helping save my life this time should I decide to mess with anything other than the usual low-voltage stuff.

My goal is to replace two existing light switches (back-to-back of each other) with a couple of Z-Wave enabled switches.

The wiring diagrams of each of the two options seem to require a neutral [white?] wire. My existing switches each only have two wires going to them which I'm assuming are the hot/load, but there are two white wires joined to each other - one from each conduit - sitting in the box.

I've attached pictures and a quick description of which wires are coming from each conduit and where they are going in case the pictures are hard to decipher. BTW, it seems the hot (if it's the red one) goes from one switch to the other in series which might be normal?

Basically, I need help knowing:

1) How to test if the white wires are neutral?
2) How to tell which of the other wires are hot and load?

Thanks in advance and let me know if anything is unclear. I'm hoping I don't have to call an electrician for something so simple - and also I like to learn, but don't want to cause any real damage.

Also, since the box has nothing for ground (no wire or terminal that I see), I imagine a mistake could be more costly.

Kitchen-side Conduit Wires:
Red – to kitchen switch, then it’s connected to dining room switch (hot?)
White – connected to white from dining-side conduit
Blue – to kitchen switch (load?)

Dining-side Conduit Wires:
Blue – to dining room switch
White – connected to white from dining-side conduit

Kitchen Switch
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Dining Switch
Name:  Dining Switch Wiring.jpg
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Wiring Diagram (New Switch)
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  #2  
Old 07-09-13, 01:24 PM
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It looks like the red is a constant hot and feeds both switches. The blue is most likely the switched hot. You can verify this by removing the switch and testing for voltage to ground or the whites.

Based on the pictures the whites are your neutrals.
 
  #3  
Old 07-09-13, 01:36 PM
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1) How to test if the white wires are neutral?
Test to the narrow slot of a polarized or grounded extension cord. They should read ~120 volts. (If separated only one may read ~ 120 volts.) Test to the box ground. They should read ~0 volts.

2) How to tell which of the other wires are hot and load?
Disconnect the two wires from the switch. The line should read ~120 volts to the box ground. The load should read ~0 volts to box ground. (The box should be grounded by the conduit so you measure to it. You could measure to neutral but you don't know which neutral is line; moot point though if the neutrals are twisted together.)

since the box has nothing for ground (no wire or terminal that I see...
Switches are grounded by their metal yoke when connected to a grounded metal box as yours probably is. Add a ground clip to the box for the green wire on the Z-Wave switch.
 

Last edited by pcboss; 07-09-13 at 05:03 PM. Reason: formatting
  #4  
Old 07-09-13, 04:15 PM
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Sigh, thanks guys.

I guess to make sense of what you said, I'd want to ask more but really, I'm just going to call a couple electricians and ask them how much for the service call and connecting two light switches.

If it is ~75 or so, I might as well just do it and then learn from what they did (and ask questions while they are there).

If it's much more, I'll ask for some clarifications.

Thanks in advance.
 
  #5  
Old 07-09-13, 04:24 PM
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Your welcome to ask for clarifications now. We are always glad to give them.
 
  #6  
Old 07-14-13, 07:02 PM
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Your welcome to ask for clarifications now. We are always glad to give them.
Thanks, and meant to ask much earlier but the week got sideways on me.

Ok, here we go.

You can verify this by removing the switch and testing for voltage to ground or the whites
By ground, you don't mean the green wires because if so, those are not hooked up.

I've tested the following a few times using a Fluke VoltAlert like this which I bought from Amazon.

* The red wires are indeed "hot". They always light up when I get the tester near them.
* The blue wires are indeed "load" as they don't light up when the switch is off, and do when it's on.
* The white wires never light up, regardless of switch position.

So not sure what ground is here, but as for the white (assumed neutral) wires, just because they don't light up doesn't guarantee they are being used as neutral does it?

- I guess basically I'm wondering how do I know these are connected to anything at all?
- Unless I can verify what they are doing, don't I run a risk of connecting them to the neutral position on the switch or not really?

In other words, I realize that since I'm not detecting a 'hot', that is good, but how do I know these were not run here for some other "load" that isn't being used and sitting behind drywall?

Test to the narrow slot of a polarized or grounded extension cord. They should read ~120 volts. (If separated only one may read ~ 120 volts.) Test to the box ground. They should read ~0 volts.
What exactly do I do to test to the narrow side of a polarized or grounded extension cord? I'm sorry but not sure of instructions

Same with testing to the ground box. And by reading 120, is it safe to assume the Fluke tester is good enough for determining that?

Switches are grounded by their metal yoke when connected to a grounded metal box as yours probably is. Add a ground clip to the box for the green wire on the Z-Wave switch.
Without seeing what is behind the wall, how would I know if this is the case? The house is about 45 years old.

Sorry for all the questions but... I'm quite the greenie.
 
  #7  
Old 07-14-13, 09:03 PM
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I've tested the following a few times using a Fluke VoltAlert like this which I bought from Amazon.
Non contact testers are just a bit more reliable than flipping a coin. You need a multimeter, preferably analog. An 8$-$15 one will give you good results. Digital multimeters are sexy looking but the cheap ones can be influenced by induced voltages.

By ground, you don't mean the green wires
No. What I wrote was,
to the box ground
and then I explained,
The box should be grounded by the conduit so you measure to it.
What exactly do I do to test to the narrow side of a polarized or grounded
One probe of your multimeter to the narrow slot and other probe to the wire being tested. Since non contact testers are all but useless my tests with rare exceptions refer to a multimeter or test light or solenoid tester.

You can tell if the box is grounded by using your multimeter to test between the box and a known good hot such as the narrow slot of a polarized extension cord.

You are I think confusing yourself by using the wrong type of tester.
 
  #8  
Old 07-16-13, 09:21 AM
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Thanks for the reply.

I guess while I love fooling with low voltage, for some reason it's the mental aspect of directly touching wires to measure, etc. and something going wrong.

It is what it is, but I'll just throw some extra $$$ and have someone come out. Sigh

Thanks again for the attempts to help.
 
  #9  
Old 07-16-13, 01:20 PM
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At the kitchen switch, red is hot or Line, blue is Load and white is neutral. Can't see the dining room wiring clearly enough to tell what is what, except that white is still neutral.

Turn the power off at the breaker before replacing any switch.

And by reading 120, is it safe to assume the Fluke tester is good enough for determining that?
No. That non-contact tester tells you nothing about voltage. That said, the voltage in your two switch "boxes" is 120, hot-to-ground.

I'll just throw some extra $$$ and have someone come out.
For $20 - $25, you could have an analog multimeter and a copy of Wiring Simplified, and be good to go.
 
  #10  
Old 07-17-13, 03:12 PM
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@Nashkat1 - Thanks.

I ordered that book because ONE day I hope to have time to read it, but right now I have so much going on and this is probably a 30-second job for any of you who know what you are doing but...

...so let me boil it down to this.

There is no where to ground the switches unless the box/conduit itself is already ground as part of the structure.

The red is indeed the hot and the blue the load.

The white has no detectable hot signal ever (that I've been able to detect), I just can't be certain it's neutral with my own comfort-level.

But let's say I hook up the new switch with white as neutral (one to each switch), and red and blue as currently used...

What is the worst that can happen when I flick on the switch?

Assume I use a broom handle to do it from a distance

I'm guessing it could cause damage to the panel since there is no way to know how the white wires are used?

I could of course damage the switch but I don't care about that as much...

I mostly don't want a fire or something really expensive to happen - but yes I know there is no way to tell so really I need to sit down, read, and get that comfort level or call someone.
 
  #11  
Old 07-17-13, 04:18 PM
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I ordered that book because ONE day I hope to have time to read it,
It's written to be readable. In addition,
Originally Posted by ray2047
You need a multimeter, preferably analog. An 8$-$15 one will give you good results.
There is no where to ground the switches unless the box/conduit itself is already ground as part of the structure.
Originally Posted by ray2047
Disconnect the two wires from the switch. The line should read ~120 volts to the box ground. The load should read ~0 volts to box ground. (The box should be grounded by the conduit so you measure to it [for hot-to-ground]. You could measure to neutral but you don't know which neutral is line; moot point though if the neutrals are twisted together.)
For hot-to-neutral, measure to the two white wires twisted together but with the wire nut off. Alternatively, you can use the slots in the female end of a 3-wire extension cord that's plugged into a known good receptacle as your reference connections. The shorter rectangle should be hot, the longer rectangle neutral and the round slot is ground. Ray explained one of the processes in post #3.

The white has no detectable hot signal ever (that I've been able to detect), I just can't be certain it's neutral with my own comfort-level.
First, white (in this case) = neutral = drain. There is no power on it until and unless a load is applied, just as there is no water flowing through the drain under your sink until and unless you open the faucet or empty a pot. Second,
At the kitchen switch, red is hot or Line, blue is Load and white is neutral. Can't see the dining room wiring clearly enough to tell what is what, except that white is still neutral.
What will it take to satisfy your comfort level? You can either trust our statements or buy the necessary tools and test for yourself.

But let's say I hook up the new switch with white as neutral (one to each switch), and red and blue as currently used...

What is the worst that can happen when I flick on the switch?
Probably pop the breaker.

Assume I use a broom handle to do it from a distance
I wouldn't. I don't like scratched or otherwise damaged switches.

Don't turn the breaker on before you turn the switch on. Install the switch(es). Mount them. Cover them. Turn them on. Then go turn the circuit back on.

I'm guessing it could cause damage to the panel since there is no way to know how the white wires are used?
If a panel could be damaged by something you could do in wiring up a couple of switches, what good would it be? Panels exist, and are built, to protect you and your house, and they do just that. It's not the other way around.
 
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