Ghost Voltage

Ghost Voltage
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HELP! I just can't figure this out. I installed low voltage lighting under my kitchen cabinets with 3-way switches. They always performed rather oddly. I would turn them on and they would light after a brief delay. I don't know why, maybe something with the transformer. Well, the transformer finally failed and I bought a replacement. I checked my wiring to try and find out why I was getting a delay and found something quite bizarre. I isolated the 3-wire and ran voltage on the black leg only. Well, my digital meter shows 57 volts on the red leg. Yes, the red leg is attached to nothing. I suspected the hot legs were touching each other and bleeding voltage through the insulation. I rang them out and there is no bleed from red to black or vice-versa. There is no short to ground. The ghost voltage also appears when I energize the opposite leg. Is this some kind of EMF? Is it safe to assume that the transformer remains energized at a low voltage even when turned off? It can't be anything with using 3-way switching with a transformer because I get the ghost voltage without the transformer being connected. The 3 wire runs behind the stove. Maybe the heat from the stove is melting the insulation enough to cause bleed, but the red and black legs ring out ok. Does this make sense to anyone? Please enlighten me, I am defeated.
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Water-Lou

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Water-Lou wrote:

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Hi, DVM is too sensitive due to high input impedance. Use plain old analog meter not to get confused.
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Buy one of these:
http://cgi.ebay.com/KLEIN-Wiggy-model-69115-Voltage-Tester_W0QQitemZ140016828695QQihZ004QQcategoryZ66991QQssPageNameZWDVWQQrdZ1QQcmdZViewItem Read this: http://en.wikipedia.org/wiki/Solenoid_voltmeter
Al
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Tony Hwang Wrote:

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Hello Tony,
Thank you for taking the time to try to help me, I appreciate it very much. I just remembered a very important point that I forgot on my original post and I completely apologize. I'm just too frustrated. I took a separate piece of three wire to a separate source altogether and performed the same test and found NO voltage on the red leg when energizing the black leg to 110v using the same fluke meter. Go back home; go to the same set up; use the 3 wire in the wall; ghost voltage on the red leg
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Water-Lou

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Water-Lou wrote:

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Yes.
Get a old analog volt meter and you will not have the problem.
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Joseph Meehan

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or load with say a 40 watt lamp while measuring voltage.
digital meters are wonderful but respond to nothing..
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Water-Lou wrote:

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This question has come up often; usually posed by those with only basic (or no) electrical training? . Suggested (basic) explanantion. Home electrical supply is AC (Alternating Current). All conducting objects, such as metal wires, have capacitance to other objects. The two wires in a cable have capacitance to each other (and possibly to other wiring even if some distance away) so at AC (even at the low frequency of 60 hertz, or 50 if you are in Europe etc.). there can be capacitive 'coupling' between an unconnected wire and another. Even though that coupling is very slight the input to a digital meter is so sensitive and of high impedance that the meter will 'see' voltage via the coupling effect. The coupled voltage is normally meaningless. It is better as has been suggested to use a test lamp or a 'Non digital meter'. Digital meters have their uses e.g. to test very sensitive circuits within electronic equipment where a test lamp or anaolg meter would interfere or mask equipment operation. This is not the case when you are dealing with domestic and commercial low impedance heating and lighting circuits. Any help?
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If I understand correctly, you tried to hook the cabinet lighting transformer into same circuit as kitchen main lighting, right? And you have multiple switches there? And the box you tapped into houses a 3-pole switch fed with a 3-conductor cable?? It is not a 220V circuit - so did you wonder why there would be a 3-conductor there? It is more expensive, so an electrician will not use it unless needed.
A bit of trivia: hook a meter in series with a 40-60 watt lightbulb and check voltage on the meter. Chances are, you'll get around 50-60 volts. Most meters are ranged to 400mA and a 60W bulb draws about 500mA. In series, they will split voltage about in half.
I had a similar problem long ago when wanting to install a new outlet and I found a very convenient cable running in the wall right where I wanted the outlet. Tapping into cable revealed 3 wires. Not giving it much thought, I wired outlet between black and white, only to get an outlet that would not work at all or have VERY low power at - guess what - about 50 volts. Was dumbfounded until I traced all wires and found out I tapped into a traveler running between top and bottom staircase switches.
Really, I also had theories about capacitance, EMF, ESP, stray currents, and other exotic stuff, while in truth I simply had it wired in a series with a lightbulb. Trace your wires. Looks like the box you hooked into is final on a power-through-fixture chain.
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scorrpio

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No general purpose meters I know draws 400mA when testing voltages. Except maybe solenoid tester. They draw more current but I have no idea how much. But solenoid tester can't give you accurate voltage reading at 50V.
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I tried that (measuring voltage in series with 60W bulb). The DMM showed 120V (same as supply).
The 400mA may be the limit for a current range on a 3 3/4-digit DMM. That would have nothing to do with the load when measuring voltage. I guess someone knows very little about electricity.
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Mark Lloyd
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Mark Lloyd wrote:

Try running that lamp in parallel. Series will not make much difference.
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Joseph Meehan

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On Mon, 14 Aug 2006 21:27:17 GMT, "Joseph Meehan"

At least with parallel, the light will work.
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Mark Lloyd
http://notstupid.laughingsquid.com
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1st off and don't take this wrong, do you understand how 3-way switches work? Most folks don't and you mention below that they always performed rather oddly. Insofar as the transformer, that should merely be 110v in across the primary (*switchleg* and 110 system neutral to power it) and then the secondary providing power to the low voltage lighting which is all effectively switched by your 110v 3 way switch system..
On Sun, 13 Aug 2006 04:13:11 +0100, Water-Lou

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cover Wrote:

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Hello Cover,
Thank you for taking the time to try to help me, I appreciate it very much.
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Water-Lou

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