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look at the diagram the hot and neutral are reversed
I didn't see the hot nuetral were reversed..........cheers;)

However it still brings up questions, see below.

It wasn't fault current, it was normal neutral current that was using the audio cable shield as a parallel path.

I've seen something very similar happen with an RS-232 connection where it actually burned up.
I see it, but with the reversed wiring of the receptacle, the current flowing on the shield, would be what ever resistance of the shield is, no?




That's a BS story.
I tend to agree.

Most laptops have a 2 wire connection, and don't use the ground. Same with phone chargers. If he had a two wire laptop, how could this happen?

He states the electrician connected the ground to the neutral wire, but there is no mention of him or whoever connected the wires up wrong in the jbox to begin with.

My take is this:

The author knows nothing about mixing equipment, and found out the hard way, why DIY websites are bad news. He tried, or had his friend try, to install new receptacles in his house, thinking he knew what he was doing, and burned up some stuff. He made the story up about an licensed electrician doing it, to make him feel better, and to share his story.


IMO....
 

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And why would someone plug their laptop in, in the studio room, and then run a usb cable into the kitchen where the fridge is, where he plugged in his new printer? Why is it there? Who puts their printer in the kitchen, by the fridge?

I dunno....

If one receptacle in the studio had the wrong wires connected in the j-boxes, one could assume that all of them are the same way, if it's a 100 yrs old, and he didn't touch anything...

Something seems fishy.....
 

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I get the moral of the story, although I don't think anyone who bootlegs will stop because of some story like this.

But it's still a made up BS story.. or else the real story has been distorted.

Too many parts of it don't jive.
 

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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 alot more than the tic ESPECIALLY the way the author describes to use it.
 

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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 alot more than the tic ESPECIALLY the way the author describes to use it.
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?

Features
Measures voltage drop under load*
Hot and neutral conductor impedances
Estimates Load on Line (ELL) up to 15A
Tests GFCIs and EPDs for proper operation
Super-bright display
High accuracies
True RMS
Line voltage
Peak voltage
Frequency
Ground to neutral voltage
Ground impedance
Identifies proper wiring in 3-wire receptacles
Identifies false (bootleg) grounds
Conducts testing without disturbing sensitive loads
Verifies isolated grounds (with 61-176 adapter)
 

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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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I get the moral of the story, although I don't think anyone who bootlegs will stop because of some story like this.

But it's still a made up BS story.. or else the real story has been distorted.

Too many parts of it don't jive.
Fun to read all the comments to this story, it's good to know your blood has flow. It's not made up, I was renting the place and am not a licensed electrician (don't tell the forum police) so I asked owners if I could hire one to do the install.

The somewhat amusing thing is as I talked to the electrician he had a bit of an air to him, and kept stating how he didn't like to do home jobs because they are so simple. Working on industrial wiring is what he enjoyed doing because they were more difficult jobs.

And why would someone plug their laptop in, in the studio room, and then run a usb cable into the kitchen where the fridge is, where he plugged in his new printer? Why is it there? Who puts their printer in the kitchen, by the fridge?

I dunno....

If one receptacle in the studio had the wrong wires connected in the j-boxes, one could assume that all of them are the same way, if it's a 100 yrs old, and he didn't touch anything...

Something seems fishy.....
The only thing I would change in the picture is the mixer, is was connected to the RPBG. As Mike made mention a lot of laptops have three prongs, and my 3 prong plug to my Apple laptop was plugged into the wall on the other side of the room into the correctly wired outlet correctly and then connected through a patchbay to the mixer. We decided not to change the picture before it went to print because that really didn't matter the concept is the same regardless of which side has the RPBG. To the electricians credit as I recall the old wires had the faded cloth colors reversed on that outlet only. I remember checking other outlets for this after that.

The only wiring I did in the house was all the cat5 cable, so no the poor electrician didn't get accused falsely. I will humbly take idiot points for not sniffing it out sooner.

As for why the printer was in the kitchen is because it was a small two bedroom house. The control room was in built in one bedroom, the other bedroom was turned into a recording booth and the high ceiling, living room and dining room were used for the live room. The only place to put the printer that seemed fit was right outside the control room which happened to be the kitchen.

My wife and two children lived in the low ceiling unfinished basement/cellar, to accommodate converting the upstairs into a studio. I am happy to answer any other questions/comments you have if I have missed any.

Here's a rough sketch of the layout.
http://bit.ly/18caEpF

Not made by me but a nice watch.
 

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...I see it, but with the reversed wiring of the receptacle, the current flowing on the shield, would be what ever resistance of the shield is, no...?
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.

Like I said, I don't see a single thing about this that seems impossible. I've seen both the main components of that story happen under separate circumstances.
 

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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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Was thinking about that this morning while going to get donuts :)w00t:) and the only part I'd like to confirm is the circuit from the grounded prong on the power supply to the shield on the communications cable.

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.
 

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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.
 
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