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  1. #1
    Reggie Russell's Avatar
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    Question Reverse Polarity and Funny Reading from my Voltage Sniffer

    Hey Guys,

    Check this picture out and tell me what you think. I was inspecting a 50 year old house today and came across this outlet that my tester read as reverse polarity. When that happens I usually pull out my "voltage sniffer" to double check that reading and I didn't get within 3 inches of this outlet without my "voltage sniffer" light coming on! Usually I have to get right next to an outlet to get a reading, does this mean anything else besides what I already know?

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  2. #2
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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Quote Originally Posted by Reggie Russell View Post
    I was inspecting a 50 year old house
    I'd say reverse polarity and no ground.

    On a 1950s house that would be right, and that grounding type receptacle would need to be GFCI protected, labeled 'GFCI protected', and labeled 'No equipment ground'.

    Jerry Peck, Construction / Litigation Consultant
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  3. #3
    Reggie Russell's Avatar
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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Sorry, forgot to mention that. Yes, I knew that as well. Does the voltage reading so far away from the outlet mean anything?


  4. #4
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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Quote Originally Posted by Reggie Russell View Post
    Does the voltage reading so far away from the outlet mean anything?
    Not grounded. That's a good indication of not being grounded.

    Jerry Peck, Construction / Litigation Consultant
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  5. #5
    Reggie Russell's Avatar
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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Thanks!


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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Using a "voltage sniffer" is a lot like using a torx driver in a square head screw. If everything is exactly right, it works. Otherwise the results are less than desireable.

    The only function you should be using a sniffer for is possible presence of voltage. And, if that reading is critical either way it should be followed up with a meter. You shouldn't interpret the distance it reacts from to mean anything definite. In some circumstances you can use them to locate drywall screws.


  7. #7
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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    I agree with Bill. Voltage is leaking from the wide slot and the moon is in Uranus...........
    Or I think that's what he said.


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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Jerry, with that tester, two lights on, indicates the outlet in the pic is grounded, but with reversed black and white.
    Ungrounded, only one, middle light.

    I see an unused ground wire in this second pic....

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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    I don't think those testers can ID reverse polarity and ungrounded. Once I start getting funny readings with the three prong tester I pull out the old fashioned 'wiggie' to figure out what's what. The three prong tester is quick and okay as long as everything is right. Once there's a problem I use other testers.

    Also, A trick with those voltage sniffers someone showed me was to put your finger over the receptacle openings you're not testing and it will usually prevent you from getting a positive reading from both. Although, the one in that picture is about as far away as I've ever seen a positive reading show up.


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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer


  11. #11
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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Quote Originally Posted by John Kogel View Post
    Jerry, with that tester, two lights on, indicates the outlet in the pic is grounded, but with reversed black and white.
    Ungrounded, only one, middle light.
    Or a boot-leg or false ground where the neutral is jumped to the ground screw.

    Those three light testers make good night lites, they really should not be used for *PROFESSIONAL* work being done by *PROFESSIONALS* - those are for DIY homeowners.

    Use them for what they are intended to be used for - night lites.

    PROFESSIONALS use PROFESSIONAL equipment, and those 3 for 10 buckaroos nite lites are not professional equipment.

    I tried to avoid going there, and avoided going there in my first response by answering Reggie's question, however, being as those 3 light testers are being promoted for HI use, I had to respond.

    If you are a PROFESSIONAL HOME INSPECTOR ... PUT DOWN THAT 3 LITE NITE LITE ... NOW BACK AWAY FROM IT ... slowly, do not be afraid ... there, that was not so bad, was it?

    Jerry Peck, Construction / Litigation Consultant
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  12. #12
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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Quote Originally Posted by Jerry Peck View Post
    PROFESSIONALS use PROFESSIONAL equipment, and those 3 for 10 buckaroos nite lites are not professional equipment.

    Acknowledged. I have a couple of multimeters in the truck. I leave my oscilloscope at home.
    I use the "nightlight" to test GFCI's and it is GOOD for that. It detects anomalys in wiring to some degree, enough to tell my client, "this outlet or this circuit needs repair."
    The voltage sniffer tells me if voltage is present, such as in K&T.
    We do a visual inspection, and a quick check for obvious problems. I don't want to portray myself as a wiring expert, just a generalist. My clients may know I'm using a cheap tool, but I try to produce a knowledgable conclusion, and they're ok with that.


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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Quote Originally Posted by John Kogel View Post
    I use the "nightlight" to test ...

    We do a visual inspection, ...
    Say what?

    As soon as you bring your tools into the house, that "visual inspection" no longer exists.

    If that "visual inspection" did not dissipate as soon as you brought your tools in, as soon as you used that testers, AND tester, ... that "visual inspection" ceased to exist.

    Do no try to kid yourself, home inspectors DO NOT DO "VISUAL INSPECTIONS", and have not, for at least 20 years or more.

    You don't need a multimeter or oscilloscope , what you need is a good circuit tester, even one of the lesser expensive SureTests will do, as other good brands will.

    Jerry Peck, Construction / Litigation Consultant
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  14. #14

    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Jerry,

    I am one who uses those 3 light cheapo's.
    On older homes, I pull random receptacle cover plates to check for false grounds (find them all the time).
    The 3 light deals are accurate for checking for polarity and most grounds --- are they not?
    The Sure Tests provide false readings as well-- do they not? (close to a panel).

    I guess I'm still waiting for a good reason to buy a SureTest........... I won't be checking for voltage drop.(maybe we need a poll to see what everyone uses). .

    I am not opposed to using a SureTest, I'm just am waiting for a great reason to buy one.

    Fire away.


  15. #15
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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    I also use the 3 light. We are providing an over all condition of the property at the time of inspection. We are generalist who look for abnormal conditions that can be observed without invasive or technically exhaustive procedures. Abnormal conditions are referred to specialist who do use technically exhaustive procedures. The 3 light tester confirms the outlet is secure, has the correct polarity, has a ground pin connection (boot leg or not) and can be reasonably assumed to be functional.

    I now stick with the 3 light made by Sperry after finding some other models indicate reversed polarity when 240v is across the Hot and Neutral. In any case the outlet would be written up as needing further investigation by a licensed electrician.


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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    I've seen this condition quit a few times in these older houses. Whoever wired the house in the beginning probably ran a home run to a light fixture and branched off with several (read 5 or 6) more runs to outlets throughout the house.

    The problem is more than likely up in the living room ceiling fixture where they thought they were wiring up the light and got a neutral on a hot!

    Seen it happen a bunch were somebody tries to save a wire and uses the black for the hot going to the switch with the white also tied into the switch to run back to the light.


  17. #17
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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Quote Originally Posted by Wayne Carlisle View Post
    Seen it happen a bunch were somebody tries to save a wire and uses the black for the hot going to the switch with the white also tied into the switch to run back to the light.
    Nothing wrong with using that type of cable as a switch leg per code, *other than the white is supposed to go to the switch and the black comes back to the lighting outlet as the hot* (easy fix, which them at the ceiling light).

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Except if you use the black going back to the light then you have the white hot going to the switch.


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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Quote Originally Posted by Wayne Carlisle View Post
    Except if you use the black going back to the light then you have the white hot going to the switch.
    Which is acceptable to the code.

    That is what I stated "per code".

    - 200.7 Use of Insulation of a White or Gray Color or with Three Continuous White Stripes.
    - - (A) General. The following shall be used only for the grounded circuit conductor, unless otherwise permitted in 200.7(B) and (C):
    - - (C) Circuits of 50 Volts or More. The use of insulation that is white or gray or that has three continuous white stripes for other than a grounded conductor for circuits of 50 volts or more shall be permitted only as in (1) through (3).
    - - - (2) Where a cable assembly contains an insulated conductor for single-pole, 3-way or 4-way switch loops and the conductor with white or gray insulation or a marking of three continuous white stripes is used for the supply to the switch but not as a return conductor from the switch to the switched outlet. In these applications, the conductor with white or gray insulation or with three continuous white stripes shall be permanently reidentified to indicate its use by painting or other effective means at its terminations and at each location where the conductor is visible and accessible.

    "per code" means that the white is permanently reidentified to some other color besides white (or green), say "black" or "red".

    I know, that permanent reidentification is never done, but that does not make using that cable improper, it makes NOT "permanently reidentifying" that white conductor improper.

    You DO always write that up as a code violation, correct?

    Jerry Peck, Construction / Litigation Consultant
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  20. #20
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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    The switch I am talking about is not a 3 way or 4 way. So I don't believe you could use the code in this installation.

    I could see it on a 3 way/4 way switch.


  21. #21
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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Quote Originally Posted by Wayne Carlisle View Post
    The switch I am talking about is not a 3 way or 4 way. So I don't believe you could use the code in this installation.

    I could see it on a 3 way/4 way switch.

    Me thinks you missed reading something ...

    (2) Where a cable assembly contains an insulated conductor for single-pole, 3-way or 4-way ...

    Jerry Peck, Construction / Litigation Consultant
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  22. #22
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    Default Re: Reverse Polarity and Funny Reading from my Voltage Sniffer

    Well I'll be damned!


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