Two way switch voltage feedback

Originally Posted By: tgardner
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I have found in a few instances, where on a two way switched receptacle that there is voltage present on the neutral when the switch combination turns off the power to the switch.


My curiosity got the best of me, I mentioned this to my Sparky buddy. He said he had found it too and still can't determine why the feedback occurs, but he thinks its a defect in one or both of the switches.

Has anyone else run across this?

Thanks, TG


Originally Posted By: Bob Badger
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Your using a digital meter aren’t you?


Try this (CAREFULLY) plug a three way adapter into the outlet you are testing, plug a lamp turned on (or any load) into this three way adapter.

Turn off the wall switch now test for voltage in one of the left over spaces of the 3 way adapter, you will have 0 volts.

Now unplug the lamp and the 'voltage' will be back.

This is induction, the wire that is connected to the switch is running along the side of other live wires and inducing a voltage on the 'dead' wire.

The voltage is real, however the current level is very small, but a digital meter is sensitive enough to pick it up.


--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

Originally Posted By: tgardner
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Bob,


I will try your idea. However, unless there is current actively flowing through the other live wire, how could it possibly create enough ( or any)of a moving electro-magnetic field to create voltage in the dead wire?

Tel you what, there was enough Current in the neutral to dimly light a plug in tester, that's why the digital meter emerged.

Thanks, TG


Originally Posted By: Bob Badger
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Both tester you had take little current to operate.


I routinely work with 277 volt circuits in pipes, I can shut off one wire in the pipe and measure 190 volts on that dead wire with my digital meter.

At that point I will pull out my Wiggys, they use a solenoid to indicate voltage and draw significant current, they will show the wire dead that the DMM shows 190 volts on.

Transformers work entirely by this induction, there is no electrical connection from the primary's to the secondaries on most transformers, only magnetic coupling. (Other than Auto-transformers)

Electricity is so cool! ![icon_cool.gif](upload://oPnLkqdJc33Dyf2uA3TQwRkfhwd.gif)


--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

Originally Posted By: jmyers
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The last time my digital multimeter showed me 0 volts, I got the shock of my life. Turns out, not only was it wrong, it was broken! icon_biggrin.gif


That smarts!

Joe Myers


Originally Posted By: tgardner
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Joe,


You have to turn it on! ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)


Originally Posted By: Mike Parks
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He is talking about a dead end. The “white wire” is a hot conductor.


Hint: there are no 2-way switches.

Mike P.