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
