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Author Topic: It slices, it dices, it tests for more AC wiring failures...  (Read 1127 times)

Jeff Bankston

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Re: It slices, it dices, it tests for more AC wiring failures...
« Reply #10 on: November 07, 2017, 12:50:07 am »

https://www.amazon.com/gp/product/B06Y68NRDV/

What's a "Live Neutral Reverse"?
maybe it's a xformer xo lug ground that has failed. Or like the time I encountered a neutral that was a full 118 volts. The so called electrician that installed the xformer did not tie the xo lug to the ground rod or cold water ground. The xo lug is where you get the neutral from.
« Last Edit: November 07, 2017, 12:53:17 am by Jeff Bankston »
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Eric Vogel

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Re: It slices, it dices, it tests for more AC wiring failures...
« Reply #11 on: November 07, 2017, 01:12:47 pm »

https://www.amazon.com/gp/product/B06Y68NRDV/

What's a "Live Neutral Reverse"?  It shows "Hot/Neu Reverse" as a separate item.

Seems the tester has two Live(Hot)/Neutral REV modes...

Hot/Neu Rev for 3 wire groundING circuits (receptacles with EGC).

Live/Neu Rev for 2 wire non-groundING circuits (screw in Edison lamp bases) with a receptacle adapter, or 2 wire polarized circuits like lamp cord etc....

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Jonathan Johnson

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Re: It slices, it dices, it tests for more AC wiring failures...
« Reply #12 on: November 07, 2017, 01:17:51 pm »

My car has neutral and reverse, but I wouldn't say it's "hot"
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John Roberts {JR}

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Re: It slices, it dices, it tests for more AC wiring failures...
« Reply #13 on: November 07, 2017, 01:22:52 pm »

Seems the tester has two Live(Hot)/Neutral REV modes...

Hot/Neu Rev for 3 wire groundING circuits (receptacles with EGC).

Live/Neu Rev for 2 wire non-groundING circuits (screw in Edison lamp bases) with a receptacle adapter, or 2 wire polarized circuits like lamp cord etc....
Think about that for a minute (no for a second). With only 2 wires how can any tester determine polarity of an AC signal...? (hint it can't).  :o

Only my OD1 can parse hot and neutral in ungrounded outlets because it grabs a 3rd environmental reference from the finger touch contact.

JR
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Eric Vogel

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Re: It slices, it dices, it tests for more AC wiring failures...
« Reply #14 on: November 07, 2017, 01:44:19 pm »

Think about that for a minute (no for a second). With only 2 wires how can any tester determine polarity of an AC signal...? (hint it can't).  :o

Only my OD1 can parse hot and neutral in ungrounded outlets because it grabs a 3rd environmental reference from the finger touch contact.

JR

Agreed, this tester is polarity blind - it only lights lamps according to closed circuit conditions and w/o ground(two wire circuit) a live/neutral rev will light all 3 lamps.  With a ground and bonded to neutral at the service panel, there is no potential on the 3'rd lamp, so a hot/neutral rev will only light 2 lights.

With regards to polarity, I was referring to a mechanical polarity concerning receptacles and screw in lamp bases - not electrical polarity.

Your OD1 is very clever indeed, I can do a similar thing with a DVM and the method can be particularly hazardous for those not experienced with metering power.
« Last Edit: November 07, 2017, 01:57:13 pm by Eric Vogel »
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John Roberts {JR}

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Re: It slices, it dices, it tests for more AC wiring failures...
« Reply #15 on: November 07, 2017, 02:09:59 pm »

Agreed, this tester is polarity blind - it only lights lamps according to closed circuit conditions and w/o ground(two wire circuit) a live/neutral rev will light all 3 lamps.  With a ground and bonded to neutral at the service panel, there is no potential on the 3'rd lamp, so a hot/neutral rev will only light 2 lights.

With regards to polarity, I was referring to a mechanical polarity concerning receptacles and screw in lamp bases - not electrical polarity.

Your OD1 is very clever indeed, I can do a similar thing with a DVM and the method can be particularly hazardous for those not experienced with metering power.
Old school neon lamp probes also work (light dimly holding one lead in your hand and probing with other) and they are current limited so safe.

JR
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Lee Patzius

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Re: It slices, it dices, it tests for more AC wiring failures...
« Reply #16 on: November 18, 2017, 11:30:52 pm »

Don't know. But I'm pretty sure you can't get all three bulbs to light up equally bright with any wiring condition I can think of, except for maybe an Edison outlet mis-wired to 240 volts. But I'll have to trace that out to se what's possible. Here's a schematic of how these things are wired.

I've seen all three lit with the grounding conductor connected at the receptacle, but not making it back to the service panel. They didn't light with equal brightness though.
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Lee Patzius

Lee Patzius

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Re: It slices, it dices, it tests for more AC wiring failures...
« Reply #17 on: November 18, 2017, 11:35:26 pm »

From inspection it appears a properly wired outlet supplies 54Vac to N1, 60Vac to N2, and 54Vac to N3

an open ground still provides 54Vac to N1, 77v at junction R7&R8, 45Vac to N2, 42Vac at N3

an open neutral  provides 54Vac to N3, 42vac at junction R7 & R8, 46vac to N2, 27vac at N1

Without finishing for all permutations that does not appear to line up with the device indications. Neon lamps have different sensitivities but probably light at 35-40Vac or so.

It is too early in the morning for me to try to figure out what is inside that new puppy.

It would really be nice if that Live whatever is RPBG but I couldn't figure out how to do it without grabbing a local reference. but???? for <$10 I wouldn't be too optimistic...  the written sales copy at amazon notes 5 patterns to read not 7.  ::)

JR

The only thing I can think of is loading line and neutral, and measuring voltage across neutral and ground. I know you know where I'm going with this!  Calibrate tester with a bootleg voltage drop, then anything higher is not bootlegged.
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Lee Patzius

Lee Patzius

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Re: It slices, it dices, it tests for more AC wiring failures...
« Reply #18 on: November 19, 2017, 01:24:18 am »

The only thing I can think of is loading line and neutral, and measuring voltage across neutral and ground. I know you know where I'm going with this!  Calibrate tester with a bootleg voltage drop, then anything higher is not bootlegged.

Dang, now I gotta correct myself. On my drive home I realized I left out the reverse polarity part. All I can think of is if it bootlegged from the receptacle's neutral terminal to ground, the above still applies, but then if fed reverse polarity, non contact voltage tester technology would be required, but I'm pretty sure those things are capacitively coupled to your body as a reference. Hence your local reference.
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Lee Patzius

Mike Sokol

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Re: It slices, it dices, it tests for more AC wiring failures...
« Reply #19 on: November 19, 2017, 07:25:17 am »

Dang, now I gotta correct myself. On my drive home I realized I left out the reverse polarity part. All I can think of is if it bootlegged from the receptacle's neutral terminal to ground, the above still applies, but then if fed reverse polarity, non contact voltage tester technology would be required, but I'm pretty sure those things are capacitively coupled to your body as a reference. Hence your local reference.

Yeah, see why this is so confusing. Without some sort of "earth" reference, you can't tell the difference between an RPBG (Reverse Polarity Bootleg Ground) and a CPBG (Correct Polarity Bootleg Ground) miswired outlet. JR's smart outlet tester and NCVTs (Non Contact Voltage Testers) both utilize your body as a capacitively coupled earth reference. Hence, they can easily discover an electrically hot ground.   
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