Electricity in a filled bathub


We have all heard the horrors of tossing a toaster or other appliance in a filled bathtub. Well, I dont understand this now. A friend told me that he had to replace the shower valve in his tub. He replaced it, leaving his tools and a plugged in trouble light in the tub when he went out to the pump house to turn the water back on. The problem, he never turned the tub faucets off. When he got back in the house the tub was almost ready to overflow. and the trouble light was under water except the bulb which was floating and still lit. He said he immediately unplugged it. (the drain was shut because he was afraid a screw would go down). How can this be? Why did a breaker not trip? He said the socket of the light was filled with water too, because he took it apart to dry it out. He said his electric drill was also under water, but not plugged in. He took that apart too.
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snipped-for-privacy@---------.com wrote: ...

...
Because it takes the overload current to trip a breaker but only a few milliamps to electrocute. How much current flow there is/would be is dependent on many things including the hardness of the water (the conductivity of _pure_ water is pretty low, it's the ionic salts dissovled in it that are the conductive path), the amount actually in a path between hot/neutral, etc., etc. A toaster is open, uninsulated elements, the trouble light was apparently one w/ a pretty tight seal around the switch so the amount of actual water in contact w/ the live terminals was quite small.
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On Thu, 16 Nov 2006 06:59:25 -0800, dpb wrote:

Very true. even in the automotive field the worst typs of shorts are what we call "resistive". this means you dont get the huge current spike that blows the fuse. You get a slower leak that does not blow the fuse.
The fuse is there ONLY to protect the wiring. The fuse is sized so that the largest amount of current that can flow through it without blowing it, will not damage the household or automotive wiring. It does not protect a person.
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On Thu, 16 Nov 2006 07:48:32 -0600, snipped-for-privacy@---------.com wrote:

Clean water isn't that good a conductor. Wet people are, though. What surprises me is that the bulb didn't blow up from thermal stress. FInd out for me what he was using as a bulb, will ya?
I suspect that, in a non-metallic and/or ungrounded tub, you'd have a hard time electrocuting yourself, anyway.
The voltage supply the voltage drain are, after all, right next to each other in whatever device you drop in the tub. why would the electricity want to make a side-trip through you? You have to touch two things at different potentials to get electrocuted.
--Goedjn
(and yet, I don't plan to test my theory...)
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If the bulb was not yet really hot when the water hit it, I suspect it's not that unusual for it to survive. Also, the really hot part would be the top, which would stay above the water.
I'm not that surprised - but I also would not be surprised if the bulb broke the next time soneone does this.
- Don Klipstein ( snipped-for-privacy@misty.com)
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snipped-for-privacy@---------.com wrote:

It takes around thirty milliamperes; that's three tenths of an ampere; to kill, sixteen amperes to trip the breaker on overload, and up to seventy five amperes to trip it magnetically via it's instantaneous trip. Does that answer your question?
--
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
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On Thu, 16 Nov 2006 17:11:06 GMT, Tom Horne, Electrician

actually, it's three hundredth's of an ampere.

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3/100 = 30/1000
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no shit!
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On Thu, 16 Nov 2006 18:51:41 GMT, AZ Nomad

And 30,000uA (microamperes).
Don't ask how many microamperes are in a kilovolt :-)
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AZ Nomad wrote:

Godd arguments for GFCIs, huh?
Jeff
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wrote:

In this whole thread Jeff, you seem to be the only one that mentions a GFCI device. Amazing. I believe they trip at 5 ma discrepancy of current flow from hot to neutral to any current not accounted for from hot to nuetral.. I have seen industrial GFI's that are rated at 15 ma.
Indeed, that is why GFCI is needed in a wr area.
Bob
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On Thu, 16 Nov 2006 17:35:45 GMT, AZ Nomad

Yes, it's three hundredths (ignoring inappropriate use of ' character) of an ampere although I'd usually call it 30 milliamperes (30mA).

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wrote:

I caught a Mythbusters where they were tossing electrical stuff in a bathtub of water to see what happened. Amusing as well as informative.
I think Buster is underpaid...:-)
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Horne, Electrician wrote:

30 milliamperes is 3 hundredths of an ampere.
- Don Klipstein ( snipped-for-privacy@misty.com)
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On Fri, 17 Nov 2006 02:34:57 +0000 (UTC), snipped-for-privacy@manx.misty.com (Don Klipstein) wrote:

Three tenths of an ampere could kill 10 people in parallel :)
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Or an unlimited number of people in series. :-p
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On Fri, 17 Nov 2006 03:42:25 GMT, AZ Nomad

True, the same current flows through every part of a series circuit.
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It should ;-) But 30ma is three hundredths of an amp. 3/10s of an amp is 300ma ;-)
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
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snipped-for-privacy@---------.com wrote in part:

Water is not a good enough conductor to usually cause the kind of short that would trip a breaker. However, water can conduct enough to cause a real shock hazard, especially if it contains salt such as from sweat, other salts, alkalis, or acids (maybe even carbonic acid from dissolved CO2).
- Don Klipstein ( snipped-for-privacy@misty.com)
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