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Old 09-21-2012, 10:29 PM   #1
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Analog multimeter shows voltage even with 3-way switch off


Friends,

Since this my first post I would like to so I have read the posting rules so I would to start off with an introduction of my background and knowledge.
I currently work as an IT Systems Administration and Engineering, or in slightly more lamens terms; I am an Information Technology Consultant for a company that specializes in designing, implementing and building computer and server networks for small and medium businesses. I have been doing it for over 15 years and I have extensive knowledge in the low voltage industry. And I enjoy it and am a pretty quick learner.

Big change came a few years ago when I finally became a homeowner. And of course I jumped right into the Mr. Fixit role and am loving it. I do have to admit that I am not a licensed electrician and I am aware of the liability and limitations of what I can do. That being said while I will always call in a professional (and have on several occasions) once I have fully understood the problem so I can in 100% accuracy describe what I need the repair technician needs to do. That has resulted in a 100% satisfaction rate with the work done as well as good payment to a professional that deserves it. This means I wish for a full and complete explanation (if possible) of what my problem is and how it can be trouble-shot and corrected (if possible with renovation or w/e); not so that I can do it but so I can get the right person to do what I need.

Hopefully no one's' eyes are bleeding yet, so now I bring you to my problem.
I live in Colorado, USA in a home built in 1971, it has a single breaker box where it receives 2, 120V lines feeding the house a total of 150A to a single breaker box. The feed lines and almost all interior wiring is original aluminum from the early 70s. Initially it was built with a fully unfinished basement. Apparently a previous owner fancied himself as Mr. DIY, with the slight difference in that he had no idea what he was doing. Built out a good portion of the basement, about 40% to code, as well as added Air Conditioning to the central air. One of the biggest fouls being the A/C wiring especially where splicing copper and aluminum without taking the required precautions for the mixed wiring. Nor proper grounding or marking such as finding red coming into a box, splicing with a white, whole thing painted over white so no color visible, and finding 120V on it. Several times.

Ok, so the problem I have is I am replacing the chandelier in the kitchen because it keeps frying light bulbs and we (myself and my neighbor, who is not a licensed pro but has extensive experience in home renovation/handyman and shares my views on hiring professionals) made a discovery. We found that a dimmer on the patio-door wall actually also controlled the chandelier that we assumed was only connected to a normal switch in the center of the kitchen. When we discovered this took an analog multimeter and checked the voltage going to the light while toggling the two switches around(we had not yet removed the light, we were testing using the connections to the light). We found that even when both switches were off there was about 30-50V still going to the light socket. Having not encountered this before we immediately flipped the breakers to the floor lighting and the kitchen and checked voltage until everything read 0 to be sure. After this we used the multimeter to check continuity between the switches, the lines and the various possible outlets/lights. We discovered that, the switch by the door had the 'source' hot from the panel or perhaps the other light circuit on the floor, not really sure atm. We also found that the he was using a 3-way switch in the room and a dimmer to control one fixture by wiring the dimmer like a 3-way and splicing a bunch of things. Another important note is that the wiring going into, and out of this box is aluminum and none of it connects to the light fixture. The 3-way switch on the wall however, has 3-way copper wire coming into it and by continuity tests it is the feed from the dimmer for the 3-way and. Also the 3-way switch is the last switch before the light socket and that wire is aluminum to the light. We then removed both the switch and dimmer and capped off misc exposed wires.

We made note of the continuity and for the last test we flipped the breaker back on and checked the voltage going to and from each box and discovered that without the switches there is voltage going to the dimmer box on the black wire and also power going to the 3-way box, but there is no voltage going to the light socket, as expected. So with this verified, turned the power off, diagram noted, we triple checked how 3-way systems should work, purchased 2 new Levitron 15amp 3-way switches. We then wired them back up exactly as they should work based on a wiring diagram and verified again by multimeter. Then before hooking the light up I wanted to test again, so we turned the power back on and checked voltages. And the voltage on the line remained around 40-50V even with both switches off, with a proper change to ~120-123V when the switches were on.

Shocked to find that putting in the proper switches didn't change the voltage we checked the 3-way set on the normal stairs that were built with the house to find the same issue, ~45V on the 'Off' side of the switch.
Ok, I deeply apologize for the severe long-windedness but I said I take this stuff very seriously, in an OCD-sorta way lol. Now then, I can say I provided enough background I think.

Now I have been trying to do my diligent research like I should into this problem and I'm seeing mixed messages about what may be wrong. I have read things such as, an open neutral, open or no earth-ground (which, as near as I have found, there isn't one), or its caused by the high built-in capacitance of digital multi-meters causing them to show a "ghost charge", I have also heard it could be caused by induction into the line from neighboring ones and is a normal thing and the low voltage doesn't hurt anything but just remember that when you touch things, etc.

So then, given the severe difference in results I have some concerns and questions.

1. Most obviously, do I have a serious problem here that warrants action before "the day comes" so-to-speak? I mean I have been here for a couple years now and while I have repeatedly come across evidence and stories of how this guy was like the king of corner-cutting, nothing has actually been damaged that I recall, just completely out of code. So I wouldn't be surprised if his horrible basement renovation created this problem, but again nothing 'bad' has happened yet other than killing 15 light bulbs in a year lol.

2. A majority of the basement wiring is in the unfinished area including the kitchen so tracing is relatively possible. If this is an issue simply caused by him splicing stuff to cut some code corners in the basement wouldn't it realistically be easy to solve by turning off the power and undoing the mess(and hiring an electrician to put it back right! )? This would be assuming he somehow cross-wired something or left a line disconnected somewhere in the mess he made.

3. If its severe, what kinda 'damage' am I looking at? I can give further details just for even a guess ballpark, just really need to know if this is bad and if so, how bad. Thanks.
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Old 09-21-2012, 10:40 PM   #2
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Analog multimeter shows voltage even with 3-way switch off


Are you testing voltage from line to neutral or line to ground. I've seen switches test out at a reduced voltage to metal box when there's a bad ground(bond for you terminology ocd folks) connection.
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Old 09-21-2012, 10:52 PM   #3
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Analog multimeter shows voltage even with 3-way switch off


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Originally Posted by andrew79 View Post
Are you testing voltage from line to neutral or line to ground. I've seen switches test out at a reduced voltage to metal box when there's a bad ground(bond for you terminology ocd folks) connection.
This is when testing the neutral. The ground in the light seemed to test out properly but the ground in both switch boxes were not even connected properly to the switches or the boxes. However, they were connected to each other and the common ground at the panel (the door is close to the breaker box, lol)
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Old 09-21-2012, 11:28 PM   #4
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Analog multimeter shows voltage even with 3-way switch off


You are testing unconnected wires that are run adjacent to current-carrying wires. Especially in a 3-way switching scenario, where the travelers are energized, and the fixture is not connected.

You are most likely picking up capacitance induction, which can give false readings on high-impedance input voltmeters.

This is a non-issue.

Try imposing a small load on those wires and see if the readings drop to -0-
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Old 09-21-2012, 11:48 PM   #5
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Analog multimeter shows voltage even with 3-way switch off


Quote:
Originally Posted by kbsparky View Post
You are testing unconnected wires that are run adjacent to current-carrying wires. Especially in a 3-way switching scenario, where the travelers are energized, and the fixture is not connected.

You are most likely picking up capacitance induction, which can give false readings on high-impedance input voltmeters.

This is a non-issue.

Try imposing a small load on those wires and see if the readings drop to -0-
Ok that is very good news, thank you.

What do you suggest I use for testing? Do I need to hook up something like a lamp or is it something more simple like a resistance load tester?
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Old 09-21-2012, 11:57 PM   #6
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Analog multimeter shows voltage even with 3-way switch off


Either way, once you test under load you will get more realistic results.
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Old 09-22-2012, 12:27 AM   #7
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Analog multimeter shows voltage even with 3-way switch off


Just to make sure what I'm thinking what you're saying is actually what you're saying. You mean that when there is a load on the line I should expect to see little to no voltage because I guess the passive resistance in the load?

*Edit* oh one more thing, one of my concerns here as well was risking damaging my new light by hooking it up to this circuit without knowing what caused the issues with the last one. Having not encountered this before we figured the idle load just burned them out, the lights were often really trashed, some blackened or even broken near the end. After the first bulb broke out we stopped turning it on. Given this idle voltage is normal then what is the more likely cause for this? Faulty fixture?

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Old 09-22-2012, 06:05 AM   #8
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Analog multimeter shows voltage even with 3-way switch off


When there is no load connected, the open wires can pick up AC by induction, which results in ghost/phantom readings on many voltmeters. Simple physics of AC characteristics.

As for your old light, you most likely have bad sockets/connections.

The electrical connection(s) at the light socket gets loose, either where the wire crimps to the terminals, or the base piece is not making good contact.

This causes excessive heat to be generated and that literally cooks the light bulbs at the base, causing premature failure.

From your descriptions, this is most likely your problem.
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Old 09-22-2012, 07:48 AM   #9
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Analog multimeter shows voltage even with 3-way switch off


hi, are you using an traditional analog (dial pointer) meter (vom) to measure voltages? In the text you say you are but in the discussion you mention digital(dmm).

just hang a single lamp, low wattage (night light) would be enough to remove phantom voltages.

analog mtrs are 5000 ohms/ volt, dmm's and vtvm's are 10 megohms/volt.bernie
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Old 09-22-2012, 10:27 AM   #10
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Analog multimeter shows voltage even with 3-way switch off


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hi, are you using an traditional analog (dial pointer) meter (vom) to measure voltages? In the text you say you are but in the discussion you mention digital(dmm).

just hang a single lamp, low wattage (night light) would be enough to remove phantom voltages.

analog mtrs are 5000 ohms/ volt, dmm's and vtvm's are 10 megohms/volt.bernie
I tried to proofread as much as possible, If I mentioned a digital in there it was a typo. Its a traditional analog, dial pointer

@kbsparky, thank you very much, You have answered my questions and the answers make good sense to me.

I also have a less related question. As I mentioned I could not locate an earth ground for the house. There is no metal rod in the ground nor any connection to a cold water pipe which I read as being possibly the only 2 ways? Im assuming it was because the house was built back before that mattered or was in the code, or w/e. So is this very critical? Should I add an earth ground to this house? or more specifically, should I get an electrician to add an earth ground to my house? I do have some expensive electronics in this house and I dont want to see them get fried on a bad surge because there is no earth ground or anything like that so it seems pretty important.
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Old 09-22-2012, 11:28 AM   #11
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Analog multimeter shows voltage even with 3-way switch off


And we are back to no ground lol. Yup you defiantly need to get a solid earth for your panel. I can't stress how important this is and needs to be done asap.
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Old 09-22-2012, 12:09 PM   #12
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Analog multimeter shows voltage even with 3-way switch off


". Most obviously, do I have a serious problem here that warrants action before "the day comes" so-to-speak? I mean I have been here for a couple years now and while I have repeatedly come across evidence and stories of how this guy was like the king of corner-cutting, nothing has actually been damaged that I recall, just completely out of code. So I wouldn't be surprised if his horrible basement renovation created this problem, but again nothing 'bad' has happened yet other than killing 15 light bulbs in a year lol."

About this, I use to buy houses and rebuil it. I'm on my 6th house now, it's from the year 1978. You know when you are working in house olders older than 10 years I assume they had had a lot of work done without permit (and usually I'm right). Is too long the list of horrors I normally find in all systems. What I do in every new (to me) house, I check the entire electric system and open every single outlet on walls and ceiling. What I found? Grounds missing or not connected, cracked marettes, outlets wired incorrectly (with/without ground, swaped ground and ungrounded), too many cables going into a same metal box, unsafe cables that were fished and are not protected or too small, metal boxes with many holes open or without the metal cover, panel breakers piggybacked with many circuits into the same breaker, cables that the owner spliced with electrician tape and aren't inside metal boxes, and the list goes on and on. And because I'm already opening every outlet, I replace for new ones every single outlet and swith, just to be sure, it is cheap insurance. In the US I see you use many plastic boxes, but I install only metal ones, gives me peace of mind. My concern is that you can actually burn the house down, and of course, if something happens insurance company will not pay you even if it wasn't your fault, because it is all non code compliant.
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Old 09-22-2012, 12:42 PM   #13
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Analog multimeter shows voltage even with 3-way switch off


The ground is a major safety concern that needs to be address as soon as possible if your main earth is missing.
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Old 09-22-2012, 02:08 PM   #14
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Analog multimeter shows voltage even with 3-way switch off


Follow-up:

Based on the responses here, my findings during other research as well as my neighbor we went with testing the phantom voltage and confirmed that the lines had no voltage on them when a small load was applied (a single light bulb). After confirming this we continued to wire the light in according to instructions and specs, testing all the time. The light, and the 3-ways are all properly working, grounded properly (boxes are metal in this case, fortunately) and the light functions fine, no heat or any other problems and the voltage both when the light is on or off is correct. To me this says that I do not have a severe, whole house wiring issue as everything seems to be behaving as it should. I do know there are issues with stuff this DIY guy did wrong but I'm fairly sure I can say that at least for its time the house was built to code. As Pirulo mentioned its the DIY that comes after that makes it worse and that is the case here but Im aware of those areas.

On the note of the earth ground. Further research indicates that it may be simply a difference in code by year. The main feed is grounded at the transformer box that feeds a small portion of the neighborhood (the supply box is in my yard so I just called the power company to ask. The house itself has no evidence of earth ground at all and I have found both here and other places that it is extremely important, especially since one assumes outlets with ground lugs are actually grounded out correctly.

I will be doing further research on that front but Im fairly positive my state allows for DIY work to be passed off by an inspector and you just have to pull your own permits, which I have done before and its pretty simply. So as long as the work had permits and passed by an inspector, insurance will cover it. But aside from deciding to install it ourselves which I doubt we will do. What kind of price range am I looking at for having an earth ground installed (the rod into the ground method) by a pro?
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Old 09-22-2012, 02:39 PM   #15
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Analog multimeter shows voltage even with 3-way switch off


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Originally Posted by OCPik4chu View Post
The light, and the 3-ways are all properly working, grounded properly (boxes are metal in this case, fortunately) and the light functions fine, no heat or any other problems and the voltage both when the light is on or off is correct. To me this says that I do not have a severe, whole house wiring issue as everything seems to be behaving as it should.
That's not a good assumption to make. There are plenty of ways to wire things so that they work, and very few ways to do it that are safe. Many of the safety problems in wiring do not show up during normal operation, but only when there's a problem. Often it's not obvious.

Quote:
On the note of the earth ground. Further research indicates that it may be simply a difference in code by year. The main feed is grounded at the transformer box that feeds a small portion of the neighborhood (the supply box is in my yard so I just called the power company to ask. The house itself has no evidence of earth ground at all and I have found both here and other places that it is extremely important, especially since one assumes outlets with ground lugs are actually grounded out correctly.
This is a great example of a safety problem that doesn't show up during normal operation. Grounding has been required for so long now that there's no way it's a code-cycle issue. The rules have changed somewhat on exactly how it must be done, but the general premise has been in place since the early days of electric power. The grounding that the power company is talking about is not the same - you still need grounding and bonding at your panel. Two ground rods, plus bonding connections to the plumbing, gas service, and probably cable TV and telephone.[/quote]
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