[GMCnet] Electric shower head heater - safe?
Don Baker
When I received it the directions indicated the cutoff valve must be upstream which would rule out an inline "tankless heater". It only turns on when you open the valve(has a diaphram operated connection when pressurized). My need to know dictated that I disassemble it to see what makes it tick. When I got to the inerds I discovered a coil of resistance wire around a plastic form much like some space heaters I have seen. But the water just circulates around the coils. There is a "ground" wire which is fastened to a screw and nut which the water would be exposed to.
My question is "why would this not shock the user"?? There would be 110 volts or 220 volts, (depending on which one you buy) with the water running across the coils and then upon your body.
The connection is two wires which the directions say the polarity is not important.
Don Baker, Burleson, Texas 77 Kingsley twin bed
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Rusty
Ok I will "stick my neck out here", confident that I will be shot down pretty quick if I'm wrong. And I promise I won't quit the forum if I am admonished.
I believe its about the path of least resistance. Obviously the a/c power is applied to the coil which will heat up like a glow plug, but only when theres water present in volume so it won't burn itself out . Its enough to heat the water pretty well. Now, water will conduct electricity, but not nearly as well as whatever the coil is made of, say some alloy of copper and tungsten. It might have say, .01 ohms of resistance or something, or, pretty much a dead short. So all that 115v ac power across that load is going to make a whole lot of current which heats the coil, yadda yadda. I do not know what the resistance of water is, but I know its going to be alot more than .01 ohms . So the juice flows where its easiest to flow, thru the coil, and maybe a couple microamps will get thru the water but that may as well be zero. So no current goes thru the stream to your skin.
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Rusty
75 Glenbrook
Philadelphia Pa
Jay Rabe
There should be NO electrical connection between the electricity powering the coil and the water. Zero, as in infinite resistance. The coil should be COMPLETELY insulated from the water. If it's not, it's a severe safety hazard (mitigated with GFI breakers) that should be immediately fixed. Your reasoning is nominally correct about path of least resistance, but water (that is not deionized) is a pretty good conductor, and lots of people have gotten electrocuted with wet appliances like hair dryers etc. that have had internal shorts (uncommon) or frayed cords (very common). It takes a surprisingly low amount of current to fibrillate someone.
J
> To: gmc...@temp.gmcnet.org
> From: g...@bauerlein.com
> Date: Thu, 12 Nov 2009 19:28:00 -0600
> Subject: Re: [GMCnet] Electric shower head heater - safe?
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Paul Leavitt
Why doesn't an electric hot water heater short to ground?? Why won't a metal pan short out an electic stove ,,,or shock you???Its because "MOST" heating elements are "MI" or mineral insulated. A small conductor surounded by insulating mineral with a metal jacket. Is the shower head heater safe???? Check and see if its UL listed or UL labeled.P. Leavitt{electrician since 78}
George Rudawsky
I had one of this type of heater when I spent a semester in the Philippines back in 1976. It was called a Bagwan Heater, and attached between the shower spigot and the shower head. It provided a little hot water or a lot of very lukewarm water, so it was better than nothing, but not that much. I obviously never got shocked by it, but it was a bit disconcerting standing under the shower with an electrical cord dangling over to an outlet in the next room!
One point that might be worth considering is that those heaters were attached to a metal pipe that was grounded. In a GMC, the same may not be true.
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George Rudawsky
Chicago, IL
75 Palm Beach
Don Baker
--- On Thu, 11/12/09, Paul Leavitt <leavi...@yahoo.com> wrote:
> From: Paul Leavitt <leavi...@yahoo.com>
> Subject: Re: [GMCnet] Electric shower head heater - safe?
Michael Lincoln
the right part of the cardiac cycle) does it almost every time in the
cath lab. That's why defibrillators are built w/ safety interlocks
that make the sync feature very hard to turn off.
Sent from my iPhone
On Nov 12, 2009, at 8:47 PM, Jay Rabe <jay...@hotmail.com> wrote:
> It takes a surprisingly low amount of current to fibrillate someone.
>
>
Don Baker
thanks again, Don Baker, Burleson, Texas - '77 Kingsley
--- On Thu, 11/12/09, Don Baker <bake...@sbcglobal.net> wrote:
Gary Casey
therefore can provide a true ground. Why not run those wires to an independent ground instead of joining them to the return ground in the breaker box? Suppose you could, but I guess someone figured the large ground wire from the box to the building ground was reliable enough.
Gary
ps: I have a suspicion that the original description of the water heater wasn't complete and that caused some confusion
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I have another question about the electrical hookup. I am not an electrician, but I know just enough to get me in trouble. The instructions with this shower heater say do not hook the "ground wire" to the neutral line, but hook it to the safety ground. Aren't both neutral and safety ground essentially the same thing? I mean the neutral wire on the electric company poles are grounded to the earth at every "telephone" pole. I know in my experience in Texas a lot of the residential service boxes I have noticed both the neutral line and the safety ground go to the same lugs.
thanks again, Don Baker, Burleson, Texas - '77 Kingsley
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George Rudawsky
There was an excellent article about RV electrical systems by the RV Doctor in the FMCA magazine a few months ago, but I cannot find the link.
RVs use a different grounding system where the neutral and ground circuits must be kept seperate for safety reasons. This should always be the case, and the only time they are interconnected is when the power cable is plugged into a land receptacle (ie 220 volt land line), when the ground and neutral are combined. I don't understand all the reasoning, but it is a major safety issue if not followed.
Perhaps our electrician members can further comment.
--
George Rudawsky
Chicago, IL
75 Palm Beach
Larry
I don't understand all the reasoning, but it is a major safety issue if not followed.
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Just off of the top of my head, it has something to do with the ability to energize the body or frame of an rv and or the chassis of the object in use. I think this was an issure when the land ground was lost. It also is a big issue when connecting inverters and generators.
Funny how design changes, in the pre GMC rvs, the frame was wood, most body skins were tin, little if any conduit used.
GMC comes along, metal vehicle and coach frame, plastic/aluminum body, with some conduit +/-....
Just what I can remember.
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Gatsbys' CRUISER :d
74 GLACIER X, 260
455/APC/4 bagg'r(ver3)
Remflex Manifold gaskets
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Purchased 08-18-04
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Larry
I didn't see any UL labels. Don Baker, Burleson, Texas
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I've been flamed for my comments on UL before but I had read and was on site at one point.
UL is supposed to be a trade mark for a company that does COMMISSIONED testing TO THE SPECS of the manufacturer.
They test no further than what the manufacturer tells them to do.
For instance, If they are told to test the flamability of a FIRE RESISTANT product to see if the material will extinguish if....
The materials catches fire and source of flame is removed.
If they are not paid, THEY WILL NOT TEST to see if an electric coil is present, perpetuating the material to continue to burn.
This is 6 of one, half dozen of the other but the UL label, not to be confused with the Union Label, Is not all that it is cracked up to be and you must research the UL testing to understand what you are being protected from. You will be surprised that in many cases, the protection is not what you expect.
( This information was backed up when I was at an ANSUL fire fighting school in upper Wisconson and UL was there testing a product for flamability. We were told what was being tested and what was not being tested. It is all in the control of the manufacturer. )
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Gatsbys' CRUISER :d
74 GLACIER X, 260
455/APC/4 bagg'r(ver3)
Remflex Manifold gaskets
_______________________________________________
Purchased 08-18-04
_