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I have no idea what you're talking about.

How does a tic tracer find a bootleg ground, and how does a plug in tester not find one?
Guys, I'm Mike Sokol, the writer of the EC&M article on RPBG (Reverse Polarity Bootleg Ground) Outlets.

First of all, the story about an electrician mis-wiring a customer's home studio is indeed true. This happened to one of my colleagues (the customer) at Shenandoah University, where I teach audio production as an adjunct professor. It did happen exactly as Adam wrote about, and he has the receipts from the electrician to prove it. And I can assure you, he does indeed know how to wire up a studio properly since he works on $250,000 mixing consoles at the school.

Secondly, a "tic tracer" (Non Contact Voltage Tester) is by far the best way to discover a REVERSE polarity bootleg ground outlet. That's because it couples to the earth ground plane via a capacitance effect. It will NOT discover a CORRECT polarity bootleg ground outlet. Ground impedance testers from SureTest and Amprobe are great at finding bootleg/false grounds of all types. The point of my article is that they can't tell the difference between an outlet with an RPBG (Reverse Polarity) and a CPBG (Correct Polarity). Now, if you had the time to drag a long wire from a ground stake or connection to the service panel ground, then you could meter from earth potential to every outlet in the house, testing for a "hot ground and neutral". But I doubt that many of you would go through that unless you were troubleshooting a problem. Even then an RPBG can be totally confusing since it will measure with correct voltages when checking from H-N, N-G and G-H with a DMM.

The real danger of an RPBG is that any appliance with a grounded plug that's connected to it will have a full 120-volts on its chassis, yet appear to operate in a perfectly normal manner. There will be no sparks, no blue glow, no hum. Everything will appear normal until the homeowner touches the appliance plugged into the RPBG outlet and anything else grounded at the same time. For instance, the microwave oven and the water faucet. Then it's deadly. And if you have a laptop with a grounded power supply (yes, lots of them do) plugged into an outlet with a correctly wired ground, and something like a printer plugged into a second outlet with an RPBG, then that USB cable will attempt to carry the full fault current of a direct short (way more than 20 amps) until it burns up and blows up the attached electronics. Same goes for audio gear such as mixers and powered speakers.

So I will challenge any of you who doubt this to get a plastic box and cover (for safety) and intentionally wire up an RPBG outlet per my schematic at the top of this thread. Then test for it with ANY brand Outlet Tester you have. I have four different brands on my test bench, and NONE of them can tell the difference between a correct polarity bootleg ground and a reverse polarity bootleg ground.

But a simple ticker (Non Contact Voltage Tester) doesn't need a separate wire run to earth ground, since it has a capacitive connection through the person holding onto it to the ground plane of the earth beneath your feet. Essentially, it's listening for "hum" just like you hear when plugging in a guitar cable. So after you build your test outlet, check it with a "ticker" and you'll see that the ground and neutral contacts are indeed "hot". If you want to take your test to the next level, plug something with a ground plug like a toaster oven into it, and wave the ticker close to the now energized surface. You won't even have to turn on the toaster oven to see this effect. But it will indeed operate normally, except that it's now a killer appliance waiting for someone to touch it and a grounded surface at the same time.

Of course, if everything is wired correctly, you'll never have an RPBG. But if you're doing an reno on a pre-1970's house, then every outlet is suspect. I personally found two RPBG outlets in my own house after 25 years of living there. And we discovered them with a ticker. Since one was powering a small window air conditioner with a hardwood floor, you would never get shocked. But if my son had plugged his grounded (Apple) laptop into the outlet beside his bed and the printer into the RPBG outlet by the air conditioner, he would have blown up his new $3,000 laptop when connecting the USB cable between them.

Please post here if you need clarification of this subject. And go ahead and build a test RPBG outlet. I've already had many initially unbelieving gear manufacturers try this out according to my working theory, and they all concur with my hypothesis. So it's now accepted as a an accurate description of a rather dangerous outlet condition that's sometimes caused by older electricians who should know better, or by DIY homeowners who don't know any better.

Mike Sokol
[email protected]
www.noshockzone.org
 

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BTW: Here's the full schematic that shows the difference between a correctly wired outlet, a correct polarity bootleg ground, and a reverse polarity bootleg ground. Note that the black and white wires were reversed somewhere inside the walls, which is what creates the reverse polarity. And, of course, ANY bootleg ground is a violation of code.

 

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That was an insert to an article that ran in this months EC&M on bootleg grounds. Problem I have with that article is the author gave examples on why plug in testers lie but in the last paragraph the only way to test for a bootleg ground is to use a tic tracer. Wtf? Id trust the plug in tester a hell of a lot more than the tic ESPECIALLY the way the author describes to use it.
Brian,

Please wire an RPBG outlet per my schematic and try it out for yourself with a 3-light tester, a ground impedance tester, and a tick tracer. The only one that will identify a Reverse Polarity Bootleg Ground is the tic tracer used exactly as I describe it. Then report back to this thread with your findings. You may contact me directly with any questions.

Mike Sokol
[email protected]
 

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No more so than current on any other wire is limited by conductor resistance. If there's enough voltage behind it, it will drive more current than the circuit can handle.
I've done a lot of experiments creating low-voltage/high-amperage ground-loops using a Glo-Melt resistance soldering transformer to inject up to 3 volts and 30 amps between audio gear. This is part of my experiments on how to find and eliminate ground loop hum in audio gear. What I've found is that series resistance of a standard length of microphone cable interconnecting two pieces of sound gear will pass about 1 ampere of current per volt of ground differential. So if a 3 volt ground loop differential will pass 3 amps of current through the signal cable shield, then a 120-volt differential (caused by an RPBG) will attempt to pass 120-amps through the signal cable shield. Of course, the current breaker will trip long before that, but I'm sure you'll find 20 to 40 amperes of fault current (probably more) for at least a few line cycles before the circuit breaker opens up. That, of course, melts down and blows up anything electronic.

See the interview/article on B&K Precision about my test setup. http://www.bkprecision.com/educatio...trical-shock-prevention-in-sound-systems.html

The reason why I know how this all works is that I intentionally design and build these types of fault situations and then try to figure out how to measure and eliminate them. Please contact me for more clarification on this largely unknown problem of Reverse Polarity Bootleg Grounds (RPBG).

Mike Sokol
[email protected]
www.NoShockZone.org
 

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I have some old grounded laptop supplies, and didn't see any continuity between the DC side and AC side. Further, in the laptop they'd still also have to have continuity between the DC supply and the USB port.
Most modern Mac laptops have a convertible power supply. You can slide the 3-wire, 8-ft AC power cord off the supply and replace it with a 2-blade plug that's goes directly into the wall outlet. And yes, the 3-wire grounded cord provides a low-impedance path from the outlet safety ground to the chassis of the laptop. I actually demonstrate this in my NoShockZone seminars as a way to reduce ground-loop hum in sound systems.
 

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I use my ideal solenoid tester to check for voltage on a conductive surface.

Place your thumb on the end of one of the test leads and the other lead on the conductive surface. The tester will make noise if voltage is present.
Hmmmm.... That could be dangerous under the right set of circumstances. According to Fluke, those solenoid testers can have an input impedance as low as 1,000 ohms. So lets assume your own hand-to-foot impedance is 1,000 ohms as well, and you're standing on a wet concrete floor. You can now have 60 volts and 60 mA of AC current through your body. At 20 mA you'll lose control of your muscles, which all tense up. This is the point where your hand clamps onto the electrified ladder or wire and you can't let go. And just 30 mA of AC current for a few seconds is considered deadly.

Now, I used to do this same trick using a neon bulb (much safer since it has a 100K input resistance) or a DMM (with a 1+ million ohm resistance) but I still don't think that's worth the risk. That's especially true when you're working alone and want to confirm the wiring is dead before reaching into the outlet.
 

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Why not just get the right tool for the right job?
You'll find that a NCVT (tic-tester) will beep from up to a foot or more away from a large energized surface. Here's a video of me imposing a "hot-skin" potential of up to 120-volts on a 40 ft RV and showing how a Fluke VoltAlert lights up from nearly 2 feet away. Too much fun!!! :thumbup:

http://www.youtube.com/watch?v=Y8h64X33aKg


 

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I'm confused...



...at about 5:02 - 5:25 , you state your body is at the same voltage as the RV....but that is not true - your shoes do provide some insulating value, just as they did when you on the cement testing the stairs.
How is your tic-tester NOT showing voltage while you have 120v applied to the RV's skin?
Actually, compared to the air path between you and ground (which is many hundreds of meg-ohms in standard humidity, and probably a lot more) your damp shoes may be only a few hundred k-ohms (probably less) between you and whatever you're standing on. So yes, if you measured between your human body and the chassis of the energized RV using a very high-impedance voltmeter , you would read zero volts. And testing between an earth ground and yourself or the RV chassis, you would read 120-volts. Seems crazy, but that's how it all works. And since an NCVT (tic-tracer) is capacitively comparing the differential voltage between its tip and the body of the pen where your hand is wrapped around it, then it won't beep while standing inside the energized RV and touching it to a faucet or door frame. But standing inside the RV and pointing it at the ground outside WILL cause it to beep due to the differential voltage. I've confirmed all this with tech support guys from the NCVT manufacturers, so I'm pretty confident that's how it all works.

Give Flash's family my deepest condolences
:laughing:
Don't worry, I've got a lot more flashbulbs.... :thumbup:

Mike Sokol
www.NoShockZone.org
 

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I can come up with many circumstances where I can be killed.

With that way of logic I might as well stay strapped to my sofa.
But this is also about the safety of your customers, not just yourself.

Since it only takes a few seconds to check an outlet for a hot-ground condition using a NCVT (tic-tester), I believe that all inspectors and electricians should add this quick proximity check to your other testing procedures (Ground Impedance Tester or even a 3-light tester).

I'm not suggesting a tic-tracer (NCVT) as a replacement for testing outlets with a good DMM or INSP-3/SureTest. But adding this additional proximity ground test to your standard outlet test procedure should allow you to find virtually 100% of all outlet mis-wiring conditions.

Your feedback is welcome. I'm an engineer and a bit crazy about measurements, but I want to know what you all think about this from an electrician's point of view.

Mike Sokol
 

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Here's another use for a NCVT. One of my lineman buddies keeps a Fluke NCVT (tic-tester) turned on in his shirt pocket while walking through the woods looking for downed power lines after storms. He says in this position it will start beeping at him from up to 10 feet away from an 11KV line, which always makes him stop in his tracks.

I've never tried this for myself, but it would be an interesting experiment. I'll be sure to video it if I get around to testing this, but I'll need a lineman to energize a high-voltage line on the ground to try it out.

That would be kinda cool...:eek:
 

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So explain how my method jeopardizes the safety of my customers.
aftershockews, let's please not get into a semantic tussle over this. So I will concede that testing your way should find a hot-ground situation and not endanger the customer, but I still think it's a bad idea from a personal safety point of view.

For example, when I was a young-pup Industrial EE back in the 70's, one of my shop electricians would test for 120, 240 or 480 volts on a wire by touching his thumb to the conduit and brushing the "test" wire with a finger on the same hand. By seeing how high his hand jumped, he could gauge the voltage. Now this was the days of solenoid testers, and we always had one in our work cart. But he liked to show this off to the young engineers. I was NOT impressed since I knew that one wrong move on his part would have killed him. I told him to stop it since I didn't want to have to fill out the paperwork if he died on my shift while working on a machine for me. But he claimed to have done this many hundreds of times without injury. One mistake and he would have been dead.

There was also an engineer in our sister plant doing essentially my EE job, and he died while showing management where an electrician the previous week had snagged an insulating glove on an 11KV line and was injured. However, the engineer pulled a pencil out of his pocket and poked it right at the energized lug, which killed him on the spot. And he was a mature engineer with 20 years experience, but just made a mistake while discussing this with his boss. I NEVER let anyone talk to me while working around live conductors. One second of inattention could be deadly.

After those two events I was REALLY careful around electricity since I began to understand how close we put ourselves to death on a daily basis. The only thing that keeps us safe is by following safe practices out of habit. Once I have to go out of my comfort zone, I get REALLY careful and focused.

So even if what you do has been safe for hundreds or even thousands of times, one mis-step on your part or a failure (short) in your test gear could be deadly. And you certainly don't want to pass this dangerous procedure on to any apprentice electricians you may be training.

So let's stay on topic about measurements and such. And let's all live long and productive lives so we can share a beer someday and talk about the crazy stuff we've done and seen.

Mike Sokol
 

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I still don't get how a tic tracer is going to tell someone a receptacle has a bootlegged ground. All it does it sense AC voltage.
It won't detect a bootleg ground with the incoming neutral and hot lines correctly wired. But it WILL detect a bootleg ground with the incoming neutral and hot wires reversed. That's why I call it a Reverse Polarity Bootleg Ground (RPBG). It's hard to wire this by accident in modern wiring, but surprisingly easy in pre 1970 wiring without grounds.

In an RPBG situation, the neutral and ground contacts are at 120-volts above earth potential, and the hot contact is at 0-volts. This strange condition will read as correctly wired using a 3-light cube tester or a voltmeter between H-N, H-G and G-N. Even using a ground impedance tester such as an INSP-3 or SureTest won't identify the reversed polarity condition, though it WILL find the bootleg ground.

What makes an RPBG so dangerous is that ANYTHING you plug into it with a grounded power cord will have its chassis electrified to 120-volts and full circuit breaker current. And there will be NO sign the appliance is electrified, since it will operate normally. This RPBG outlet can exist for years or even decades before someone touches something plugged into it and anything grounded at the same time. Then it's very likely deadly.

My point is that by adding a simple NCVT check to your standard outlet testing (especially in pre-1970's wiring) you may find a potentially deadly RPBG mis-wiring condition and save a life. And that's a good thing.

Does that make sense?
 

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So ONLY bootlegged grounds that aren't even bootlegged, because they're just completely wired wrong, can be found using a tic tracer?
Well, it actually IS a bootleg ground. But the white and black wires were somehow swapped in the walls somewhere. I've seen this in a lot of old K&T wiring since everything is black, and many times the neutral was switched for lights and such. Those were crazy times....
What does the tic tracer do differently that distinguishes it as an improperly bootlegged, bootlegged ground receptacle? I'm supposed to walk through houses waving my tic tracer in the air, 2 feet away from receptacles, to see if it'll find these one in a million wrongly wired receptacles?
Well, I think that an inspector is "supposed" to check every outlet for proper ground or a GFCI, using a 3-light tester at the very least, and a SureTest or INSP-3 for commercial installations such as hospitals. However, that's probably wishful thinking on my part.

The reason why a tic tracer can find a REVERSE POLARITY Bootleg Ground is that the outlet now has it's ground and neutral energized to 120-volts with a low-resistance connection. So if you happen to be measuring an outlet due to a customer complaint about sparking or feeling a shock from an appliance, then the tic tracer (NCVT) will tell you what's really going on with the outlet in a few seconds.

Remember, standard voltage metering between H-N, H-G and G-N will NOT find a bootleg ground of any kind (unless you load the circuit and look for a voltage change between G-N). And Ground Impedance testers (INSP-3 and SureTest) will NOT tell the difference between a Correct Polarity Bootleg Ground and a Reverse one. And I've seen a few extension outlets added onto the end run of a RPBG outlet, in which case there is no visual or operational difference between an RPBG and a 100% properly grounded outlet. Except that the RPBG has electrified the refrigerator or microwave chassis to 120-volts.

I only present the idea of using a tic-tracer to look for hot outlet grounds as one more troubleshooting tool when looking for wiring mistakes. Thinking back over my 40 years of electrical work, I can remember dozens of situations in rental units and performance stages where there were shocks that I didn't understand, and this would have explained it all. In fact I first found an RPBG outlet in my dad's rental property in the late 70's right after a housing inspector validated all the wiring after a reno. The guy renting the place said he was feeling a tingle from his air conditioner while standing on the concrete floor, so when I measured from a water pipe in the bathroom to the ground in the outlet, I found 120 volts. Inside of the new grounded outlet was a G-N jumper. Of course it was old K&T wiring where everything is black so the contractor "guessed" which was white and black.

I also found a RPBG outlet in a church just last year where I was teaching a sound mixing seminar with 20 mixing boards on the desks for students, all of which were plugged into a "new" outlet on the wall. Everything worked properly without any hum or buzz in the sound sytem, but when I got my Fluke VoltAlert near any of the mixers, it started beeping. I found that the "new" outlet was part of a reno that some of the church members has helped with. And, of course, rather than run new wiring through the concreted block walls, they just did a bootleg ground to "upgrade" the outlet. While none of my students would have been shocked since they were all on a carpeted floor, if anyone in the corner would have touched the metal surface of a mixing board while leaning against the metal radiator cover (grounded, of course) it would have shocked them, and possibly resulted in death by electrocution. Not something I like to see in my seminars.

So now I'm always suspicious of the "new" outlet in an old building. That's where RPBG outlets are a real possibility.

Mike Sokol
 

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No...what he is saying is if the neutral and hot are switched on a receptacle and then someone bootlegs the ground (to the hot now) you will have 120 volts on the on the ground pin. A tic tracer will not find this problem unless something with a large enough metal surface which is connected to the ground pin of a 3-wire cord is plugged into the miswired receptacle.

Edit: Typing while Mike posted
Actually, a tic tracer WILL find the "hot" ground in an RPBG receptacle by itslef, but only when you get close to the front of the outlet, perhaps an inch away. But a tic tracer will light up from several inches to a foot away from a large energized surface caused by a RPBG or any other hot ground problems.

See the picture below. And please wire one up for yourself and try it.

Mike Sokol

 

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Mike, what is red/green designation there?

~CS~
In the picture above, Green indicates the NCVT is turned on without sensing any voltage, while Red/beeping means it's sensing at least 40 volts AC. This is a standard 90-1000 volts NCVT. The low-voltage versions designed for 24-volt control circuit tracing are too sensitive to use around 120-volt outlets, since they can't tell the difference between a normal hot and neutral outlet contact. The tester in the picture is a Klein NCVT-1. Klein also makes a NCVT-2 version with both high and low voltage settings, using a green light for on, red light for high voltage (over 40 volts) and blue light for low voltage (under 40 volts), but it's a bit too complicated for most outlet testing, I think.

I have NCVT's from half a dozen manufacturers and try them on all types of wiring situations. Right now the Fluke, Amprobe, and Klein products are my favorite testers in terms of ruggedness and reliability. But your mileage may vary...

Mike Sokol
 

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I admire Mike's passion on this issue.

Seems there's something to it, it's just a little above my head. Where I live it's all newer homes (60's and newer), so I don't run into bootlegged grounds. Guess I forget the rest of the world has much older communities and people do bizarre things over the years.

So the situation would be a homeowner getting shocks from a receptacle (or device plugged into a receptacle). The electrician fixes the problem.. then does a quick walk through, checking other receptacles' ground pin for live power and a bad bootleg?
Yup, exactly. Bootleg grounds (and RPBGs in particular) are like rats. Where's there's one, you can probably find a lot more. ;)

Mike Sokol
 
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