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Closed switches or breakers have noise voltage?

Discussion in 'General Electronics Discussion' started by Danny Daviss, Mar 20, 2013.

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  1. Danny Daviss

    Danny Daviss

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    Mar 16, 2013
    When I close a switch or close a breaker and taking a reading on my DVM, I need a voltage , it should be zero volts , but I get 3 volts from the induced voltage or noise?

    Why is that?
     
  2. Danny Daviss

    Danny Daviss

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    Mar 16, 2013
    it should be zero volts closed and 120 AC when switch or breaker is open

    But I'm reading 3 VAC when the switch or breaker is closed , why is that? is this an induced voltage or noise with voltage?
     
  3. CocaCola

    CocaCola

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    Apr 7, 2012
    Anything else on the circuit that might be back feeding?
     
  4. Danny Daviss

    Danny Daviss

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    Mar 16, 2013
    what's back feeding?

    When the switches or breakers are closed they should be Zero volts to ground
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Are you measuring to ground or neutral?

    Try measuring between neutral and ground. I bet you'll find a few volts there if your ground isn't bonded to neutral or if there's a high neutral current.

    If there's a load attached, then active will go to the neutral potential when the circuit breaker opens (unless something is back-feeding it as CocaCola suggests).

    Don't kill yourself doing this.
     
  6. CocaCola

    CocaCola

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    Apr 7, 2012
    Maybe it should be zero, are you measuring neutral or ground? Because neutral backfeeds are quite common in structure wiring... They can be aggravated by an imbalance system or the lack of proper bonding to ground...

    Are you one in the same with Danny Davis

    If so I guess we are back to suggesting GOOGLE...

    http://en.wikipedia.org/wiki/Backfeeding
     
  7. Danny Daviss

    Danny Daviss

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    Mar 16, 2013
    measuring neutral to hot which is 120 VAC

    Measuring Neutral (white wire ) to ground i think or its neutral again to a breaker

    One side of the switch goes to HOT , the other side of the switch goes to either neutral or ground

    But when I'm measuring the AC voltage , I measure with my black probe to the neutral white wire to the HOT sided lug when the switch/breaker is open, It reads 3 VAC when the switch is open and I'm measuring with my DVM meter from the white neutral wire to the HOT black wire sided lug on the switch

    I get 3 VAC when the switch is open, measuring from the HOT side of the switch/breaker lug terminal to the white neutral wire
     
  8. CocaCola

    CocaCola

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    Apr 7, 2012
    Nope, one side of the switch should go to to hot, the other side goes to the fixture, neutral also attaches to the fixture and you have a circuit...

    Sorry can't follow what the heck you are doing...

    As Steve and I stated neutral and ground are NOT the same, neutral will in many cases hover above ground, it's not proper but it's quite common...

    I'm of the opinion that if you don't understand mains wiring (it's clear you don't) then you have no business playing with it unless you are under the direct supervision of someone that does understand it...
     
  9. Danny Daviss

    Danny Daviss

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    Mar 16, 2013
    Yes I'm measuring from the HOT to the fixture, when the switch/breaker is OPEN and it measures 3VAC why? the switch is open and there is AC voltage
     
  10. CocaCola

    CocaCola

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    Apr 7, 2012
    I have already told you, something is back feeding, you have an imbalanced load or your neutral is not bonded properly... There are other things that can aggravate this effect as well, long runs of wire (electricity follows the path of least resistance even it's the wrong path) or improperly wired reversed polarity sockets (potentially back feeding)...
     
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    I'm still not sure what you're measuring. You have only mentioned HOT (active), and not what you are measuring it with respect to.

    Since it appears the load is a globe (maybe??) then it connects the now isolated active to neutral. Presumably you are measuring the isolated active to ground which is essentially the same as measuring from neutral to ground.

    Mind you, I have to make a lot of assumptions because you write a lot of words, but tell us very little.
     
  12. Danny Daviss

    Danny Daviss

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    Mar 16, 2013
    What is an imbalanced load?

    What does neutral is not bonded properly mean?
     
  13. Danny Daviss

    Danny Daviss

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    Mar 16, 2013
    Respect to Neutral

    The Breaker has 2 terminals
    1.) HOT on one side
    2.) Neutral on the other side

    I'm measuring when the Switch/breaker is OPEN which measures 3VAC , why? it should be zero volts since the breaker/switch is OPEN not closed
     
  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Danny. Learn to use Google.

    Send me a PM once you've used Google to find out what these terms mean. Include in that PM a description of these terms. If I find them satisfactory I will reopen the thread. If I don't reopen the thread then Google some more.

    You waste valuable time because you are lazy.
     
    Last edited: Mar 20, 2013
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