Even better is now apply this technology to cordless phone charging for kiosks in airports but not bars. Not enuf security.
make a million denaros.
I don't think the problem was reported accurately.
"I'm getting a shock off the countertop in the bathroom"
Between the metal edge and what is my 1st question.
a) the plumbing?
b) wet feet?
My second question is …Was there a grounded outlet or transformer outlet or a GFI outlet?
My 3rd question is.. was the 40~50Vac measured on a DMM with 1MΩ probe impedance or what?
My 4th question is.. Would you get the same voltage if the charger was moved away from the counter surface? Plug reversed? or brush removed from cradle?
Answers to these questions will give a more accurate conclusion.
I often measured 50Vac just with my body and stray hum in any room on a 10MΩ probe and floating gnd clip. This is just common mode stray E field that becomes differential relative to the probe ground floating.
If you don't have a grounded outlet with GFI installed yet. I suggest you do so promptly. I showed my nephew how to install one without any experience when he moved into my place at 15yrs of age. He had one of the fancy Braun toothbrushes and I had no outlet in my bathroom.
I suspect your leakage was promoted by high humidity in the wood studs and conducted to the metal rim.
I was in London in 1984 on a business matter, and the electrocution was a big news item in the papers at the time. It has been some time, but as I recall, a contractor had replaced the outlet and wiring near the mirrored medicine cabinet and switched the hot and ground leads making the metallic frame of the victim's razor electrically "hot." While shaving, the victim touched his razor and the water spigot which was indeed at ground potential, and was electrocuted. I believe the power supply (the "mains" as they say over there) was 50 Hz, 220 Vac.
AR, you are right on. The voltage was probably measured between the metal trim and an earth ground point. I suspect that water has gotten into the charger and caused a leakage path to the trim. A GFI would trip if the leakage was in the 5ma range but a person can feel a shock at less current with wet hands. Assuming a 10meg input meter, the leakage was about 1/4 ma.
I also detected a misunderstanding of the GFI operation. A GFI cannot detect a fault on the secondary of a transformer. If the voltage was indeed coupled from the charger winding (it was not), then the GFI would not detect it as leakage current.
@Myron: We were in London in 2008 (just watching the economy collapse around us) and there were no electrical outlets in the bathroom, just as we found in Paris the previous week. The Paris hotel provided an extension cord so my wife could dry her hair using the bathroom mirror but the London hotel refused to provide an extension, said it would violate Code. So, I'm surprised to read your comment about switched leads in a bathroom outlet.
The toothbrush charger would have to be emitting a major field to induce that much current in the trim, probably does not have enough copper in the base to create that kind of field. You suggestion to look elsewhere is a good starting point. (Both of our induction toothbrush chargers perform just as you mentioned: when the brush is ~>5 mm from its dock it stops charging.)
I think you guys need a new editor, someone that knows at least a little something about electrical theory. If the toothbrush charger had that much magnetic flux then all kinds of strange things would be happening near the charger. The toothbrush could be charged while sitting a number of feet from the charger. Any old cassettes would be erased of their recordings and strange movements of nearby ferrous metals!
When the primary in the base is efficiently coupled to the seconday in toothbrush, you probably get 3 volts and 20 milliamps to charge the battery.
But the primary in base can not be efficiently coupled to the loop of metal trim. Think about what the magnetic field pattern around the base looks like. With the toothbrush in charging position, the field should be well confined. With the toothbrush off, I would expect the flux pattern to be the size and shape of grocery store donut. Where can you place the base so that the loop cuts through any significant part of the donut.
Take your voltmeter, short the leads together to get a two-foot loop. Lay it around the charger. What do you see? Nothing like 50 volts.
Change the meter over to milliamps and repeat the experiment.
So I'm showering in a campground shower house and the lights keep getting dim, and then bright again. I'm thinking "boy they sure have a piss poor electrical system here".
I begin to realize that the lights seem to dim every time I stand up straight, and that a couple of times the room went completely black.
I FINALLY realize that they are getting dimmer as my head approaches the shower head, and that the room is black when my head touches the shower heat.
My friend in the next stall confirms my fears. The room isn't getting darker...MY VISSION IS FAILING.
Apparently there was some recent plumbing work done, and the building ground wire which was connected to the copper plumging didn't appreciate the new plastic main that had replaced the original steel pipe from the well.
I was basically semi-electrocuting myself as I became a conduit for the high ground potential making it from the shower head to the drain via my body and the high mineral water "rheostat" I was creating with the gap between my scalp and the shower head.
I'm having a hard time understanding how the metal band on your countertop could act like a secondary winding driven by the primary in the base of your toothbrush holder/charger. I have such a toothbrush and the magnetic flux in the base is so feeble that moving the tooth brush a fraction of an inch from the base stops the charging effect in the toothbrush. I just can't see any way this weak field could induce a current flow in the counter trim strip. Furthermore, the trim strip is essentially a one-turn secondary. if it's a continuous strip, it's a shorted one-turn secondary with zero volts output, or if not a closed loop, and being one turn only, I believe its induced voltage would be so low as to be imperceptable.
There are other possible causes of the shock that was felt. I would look to see if the whole bathroom lighting and accessory outlets have been wired correctly, and that the ground and hot supply leads weren't mixed up resulting in electrically hot (supposedly) grounded surfaces.
I'm sure there are other cases like this, but I clearly recall a situation in London, England where an electrician mixed the hot and ground leads to a bathroom outlet that resulted in fatally shocking the user of an electric shaver.
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