Replacing two prong outlets and creating bootleg grounds can cost you.
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a big 10-4
where i do biz, it's a fairly huge problem
it's sometimes a real chore to weed them all out too
in the past, i've tried assessing N to G in the unenergized state, simply disconnect the MBJ and one can go after individual branch circuits right from the panel
not a perfect science, some considerations apply....but it's a start.....
~CS~
where i do biz, it's a fairly huge problem
it's sometimes a real chore to weed them all out too
in the past, i've tried assessing N to G in the unenergized state, simply disconnect the MBJ and one can go after individual branch circuits right from the panel
not a perfect science, some considerations apply....but it's a start.....
~CS~
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Good stuff:thumbsup:
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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?
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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...don't forget to unplug the oven and dryer if electric.
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...and his patience!
:laughing:
BTW Mike....thanks for posting this:
[..must be amazing to have 3 hands :laughing:]
IMHO, your companion piece should also be posted:
What happened to the link to your website?
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Yup, that's what it is. Costs around $17 at Home Depot, a little less online.
http://www.homedepot.com/p/Klein-Tools-Non-Contact-Voltage-Tester-NCVT-1/203578320#.UiTStj9MsVc
Mike Sokol
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What I don't understand is, one of those receptacles is suppose to be wired in reverse polarity. The plug in tester will not detect that because the ground HAS voltage on it ?
That's correct. A 3-light plug-in tester won't tell you there's a reverse polarity if the ground is also hot. Seems crazy but true.
I knew about bootleg grounds from the 70's, and even found a few RPBG outlets over the years while checking voltage between a water pipe and the ground pin. But the real epiphany came when I tried to design a high-current 3-light tester using 100-watt bulbs to sniff out safety grounds with a high-resistance problem. First I downloaded the schematic of a standard neon 3-light tester, then took one apart to confirm the operation. After doing a circuit trace on paper of all possible outlet problems there appeared to be one very dangerous condition where the ground and neutral screws on the outlet were bootlegged together and accidentally tied to the hot wire, while the hot screw was tied to the neutral wire. Seemed too crazy to work, so I bought a few plastic boxes and covers at Lowes and built a 3-fer test rig with three different wiring conditions in about 10 minutes (the very box you see in the picture). I tried my 3-light tester and confirmed it couldn't tell the difference between a correct outlet and an RPBG. Measured between H-N, H-G and G-N and confirmed it measured as correct even though the ground and neutral were at 120-volts to earth. Then tried my SureTest Analyzer and confirmed it also would tell you the outlet was correct polarity, even though there was an obvious reverse polarity with the ground and neutral contact sitting at 120-volts above earth potential. Yikes!!!
A few more tests with my wife's toaster oven, a guitar amp, and laptop computer with a grounded power supply confirmed my hypothesis. NONE of the standard outlet test methods we were all taught and use daily could find what I now call an RPBG. But grabbing my trusty Fluke VoltAlert from the bench showed the outlet ground and anything plugged into it with a grounded power cord was indeed "hot". REALLY HOT!
I then called my electrical engineering contacts around the country and asked them to confirm my hypothesis, and every one of them thought I was crazy at first. But once they built their own RPBG and ran the same tests, all confirmed that an RPBG outlet behaved exactly as I described, and that the electrical industry had pretty much ignored the problem for the last 40+ years. You can see a little warning on the box for the 3-light testers which states there may be "some" wiring conditions it won't find. It just doesn't tell you what that condition is or how dangerous it can be.
So please, go ahead and build an RPBG test outlet (in a plastic box with a plastic cover and a nylon screw for safety) and try to find it using any tester you've got. Unless you run a wire to a ground rod, water pipe, or known-good ground, you won't find it. But poke it with a NCVT (tic tracer) and you'll find it in a few seconds.
Please pass this info onto any other electricians or inspectors you know since it could save a life someday. And keep me posted of your own experiences if you find one and take a few pictures.
Mike Sokol
[email protected]
www.noshockzone.org
Still gotta question the wire to the receps, if you don't mind?
It's a house, over a hundred years old, with knob and tube wiring, with no ground with the wires, the color of the neutral wire had faded, and the junction box from long ago, had the wrong wires connected to it. This is what the electrician didn't know, because he didn't look for a miswired J-box?
I am close?
It's a house, over a hundred years old, with knob and tube wiring, with no ground with the wires, the color of the neutral wire had faded, and the junction box from long ago, had the wrong wires connected to it. This is what the electrician didn't know, because he didn't look for a miswired J-box?
I am close?
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Nice thought provoking theory Mike
~CS~
~CS~
Old K&T wiring had all black insulation. The hot was black, the neutral was black, and there was no safety ground. To make it even more confusing, many times the (black) neutral was run to the switch for the lights. So unless you compared the voltage to an earth ground, it was really easy to get confused.
Later K&T wiring was sort of gray (neutral) and black (hot), but after 80 years of oxidation, everything looks like the same color. Again, it's very easy to get the hot and neutral reversed when connecting to K&T.
Of course, it's a code violation to do any sort of bootleg ground, or to tie into open K&T wiring at all. And you're supposed to convert any 2-wire receptacles to a 3-wire GFCI with an unconnected ground screw. Since a GFCI doesn't require a ground wire to operate at all, then the consumer is safe from shock. However, the receptacle is supposed to be marked as "No Ground" but I've never seen one marked like that other than my own installs. Maybe I haven't been looking hard enough.
Just how do you guys deal with "upgrades" to grounded receptacles in old buildings?
Mike Sokol
[email protected]
Kinda figured that was the case. You see, old K&T was aluminum, and never that I've seen, was in a j-box. The electricians who installed it soldered splices and wrapped them with a friction tape. It was quite the skill to wrap and solder K&T back then.
Now that we know there was no J-box, and aluminum wiring someone was playing with, this begs the question.....how did you create a bootleg from aluminum to copper wire.
While you point out an interesting dilema on paper, it s clear to me, this actual problem never happened the way it was explained. It seems you two created a problem on paper...in theory..and then wrote up a solution for some reason.
Don't feel bad about it. Manufacturers who brought up the AFCI stuff did the same thing. First they found a problem on paper, then created a solution, and then forced everyone to believe them with their "err on the side of safety BS".
You should write an article on how the electrician who you blamed this problem on, used standard wire nuts to splice the K&T to copper pigtails, and how that burnt your studio down.
Cheers.
I'm not sure how to respond to this. First of all, I'm not the guy in the studio with the damaged equipment. I'm an independent consultant to the pro-audio industry and a technical writer with 10,000 articles in print. The guy with the studio just happens to be one of the professors at the same university where I teach. I was writing this article last year and looking for real-world examples. Adam was a great example of what can go wrong.
Secondly, I'm not sure where you got the idea that old K&T wiring was aluminum. All of it I've ever seen was copper. Aluminum wire was an invention in the 50 and 60's (if memory serves) and aluminum oxide (corrosion) as a cause of electrical fire is an entirely different discussion.
Finally, as a consultant to the pro-audio industry, I have had dozens of examples of this "grounding problem" sent to me in an effort to come up with an explanation for the equipment failure. This isn't something I made up looking for fix. It's something I've personally seen over the last 40 years of electrical work, but finally put it all together into a simple idea for a failure mechanism, diagnostics, and solution. It's simple enough to test for using a tic-tester.
While in the example at the beginning of this thread there was a licensed electrician involved, I do believe that most RPBG conditions are probably caused by a DIY homeowner, an old electrician who's done bootleg grounds as a cheap/fast fix, and most recently by volunteers at churches adding "grounded" receptacles to music stages to accommodate modern music. I may have even found some of these in my school where the plant maintenance crew replaced a few outlets a few years ago.
So while I can't provide any data as to how many K&T wiring hack jobs have created a fire. I'm positive there was no "fire" in the above studio example caused by aluminum oxide issues from aluminum wiring. This was definitely caused by a difference in voltage between two different receptacle grounds. That's what caused the sparking and electrical damage to the gear. There was NO fire at all.
But I do hear your frustration at ordinances and codes that seem to be added without any reason. Rest assured, I'm a real-world kinda guy who's only looking for reasons why things fail. These are not some hypothetical situations in a lab, but real failures in actual buildings.
And no, I don't sell any products or have anything to profit from this campaign. It's just a very interesting problem that's not been formally identified by the industry.
Mike Sokol
[email protected]
www.noshockzone.org
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