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Wallwarts in the toilet`

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dknguyen

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We have a touchless battery-powered toilets at work here but it's pretty annoying to have to replace the batteries. With so much water around, is it safe to use a wall-wart and run the output wire into the toilet to wire it to the wall? Output voltage would be 6VDC-9VDC, depending on whether it's a faucet or toilet. The battery holder for the toilet sits inside the tank of the toilet above the water line.
 

JonSea

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Most wall-warts have leakage current at half line voltage. Usually, it's just enough for a tingle, but with wet hands or standing in water, it may be more shocking (couldn't resist)!
 

dknguyen

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Most wall-warts have leakage current at half line voltage. Usually, it's just enough for a tingle, but with wet hands or standing in water, it may be more shocking (couldn't resist)!
What about medical wall warts?

All the faucets at work are similar but since the mechanism is in the cabinet below the sink, along with an outlet, I already replaced all those.
 

ronsimpson

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Leakage specification is measured Current, not Voltage.
This is the max allowed not what you will actually get.
To get any current you will have to touch the electronics and water. Is it possible to touch the electronics?
You can connect one of the power supply wires to a copper water pipe. If there is current it will go to ground not you.
 

crutschow

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Since the water is in a porcelain bowl, which is an insulator, and the person doesn't normally come in contact with the water in the bowl, I don't see any particular danger, even if the wall-wart did have a small leakage current.
 

be80be

Well-Known Member
Use a real wall wart one that steps down with a real transformer then outputs 6 volts it would end up about the same as a battery.
If your safe with a battery you'll be fine.

I've fix boat dock's you did't get a shock till you touched a metal glide wire.
But I would try that at home the old power wire someone figure they save money and run
the service wire in the lake and to the dock that did cause a shock them the swimmer
grabbed the dock.
 
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dknguyen

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Use a real wall wart one that steps down with a real transformer then outputs 6 volts it would end up about the same as a battery.
If your safe with a battery you'll be fine.

I've fix boat dock's you did't get a shock till you touched a metal glide wire.
But I would try that at home the old power wire someone figure they save money and run
the service wire in the lake and to the dock that did cause a shock them the swimmer
grabbed the dock.
I've never given it much thought...but what do those new smaller, lighter switching wall warts use for isolation? Don't they still use a small high frequency transformer as the switching inductance rather than a big 60Hz transformer? Of course, I guess if the circuit fails no more stepdown occurs as on the traditional 60Hz transformer wall wart.

Because the only one on Digikey that meets my requirement (if we're going medical) is this one:
http://www.meanwell.com/Upload/PDF/GSM06U/GSM06U-SPEC.PDF

Otherwise, there's this transformer one:
http://catalog.triadmagnetics.com/Asset/WDU6-300.pdf
 
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KMoffett

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"and the person doesn't normally come in contact with the water in the bowl" Except for that stream of electrolytic fluid between you and the water in the bowl. :eek:

Ken
 

crutschow

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Except for that stream of electrolytic fluid between you and the water in the bowl.
What I meant was the water in the tank.
 

dknguyen

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This is the max allowed not what you will actually get.
To get any current you will have to touch the electronics and water. Is it possible to touch the electronics?
You can connect one of the power supply wires to a copper water pipe. If there is current it will go to ground not you.
Not unless you take the lid off the tank take the lid off the box pry open the box.
 

tcmtech

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Unless your body actually completes a viable circuit between two or more points you aren't going to get a shock from anything.

GIven that so much of modern plumbing is plastic on both the supply and outgoing end creating a viable circuit solidly enough to get a perceivable shock is extremely unlikely.
 

be80be

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He be ok i just unplug before servcing. I dont see a user shock.
Hell they got kitchen faucet that plugin the wall
Your water heater has 240 heating elements they go bad all the time no shock threat
 

dougy83

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I've never given it much thought...but what do those new smaller, lighter switching wall warts use for isolation? Don't they still use a small high frequency transformer as the switching inductance rather than a big 60Hz transformer? Of course, I guess if the circuit fails no more stepdown occurs as on the traditional 60Hz transformer wall wart.
The switching supplies use a small transformer, but there is leakage due to a HV capacitor that connects the primary to the secondary (used to reduce the switching EMI). The old transformers don't have that capacitor.
 

dknguyen

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The switching supplies use a small transformer, but there is leakage due to a HV capacitor that connects the primary to the secondary (used to reduce the switching EMI). The old transformers don't have that capacitor.
I wonder how the medical switching transformers do it (at least I assume they're switching due to their small size). Their leakage is crazy low like the regular traditional medical wall warts. Seems like such a snubber wouldn't be allowed on a medical wall wart.
 

ChrisP58

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The switching supplies use a small transformer, but there is leakage due to a HV capacitor that connects the primary to the secondary (used to reduce the switching EMI). The old transformers don't have that capacitor.
That, plus switch mode transformers need tight magnetic coupling. To reduce leakage inductance, the primary winding is often split in two with the secondary sandwiched between them. That makes for a lot of primary to secondary capacitance. That capacitance, plus the high switching frequency, makes a good path for leakage current.

The windings in line frequency transformers don't need to be as tightly coupled. More often than not, they're wound side-by-side on partitioned bobbins. So the interwinding capacitance is lower. That, plus the much lower SINE wave frequency (no square wave harmonics) and you get a much lower leakage current.
 

tcmtech

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That, plus switch mode transformers need tight magnetic coupling. To reduce leakage inductance, the primary winding is often split in two with the secondary sandwiched between them. That makes for a lot of primary to secondary capacitance. That capacitance, plus the high switching frequency, makes a good path for leakage current.
And what are the real world current level one would encounter at the DC end of the device with such units when the person themself is not any part of a well defined circuit? My guess is way below the typical ~.5 ma level most people would perceive.

When you get into the theoretical top end values measured in the sub milliamps levels (<1/10th what most GFI devices trip at) your basically isolated well enough to not be a concern and most any common walmart is going to have real world currents way below that.

There's being safe and then there's just being paranoid.
 
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