Forum Discussion

rekoj71's avatar
rekoj71
Explorer
Jul 04, 2015

Stray Voltage?

My RV has a stray voltage problem, and I'm wondering if anyone has any good ideas on how to find or fix the problem.

My daughter complained to my wife that she thought she was getting shocked when touching the bare metal on the outside compartment door. My wife dismissed it when she checked it several days ago but last night my daughter said it happened again and my wife confirmed it, but when I went out and tried it nothing, until I realized they were standing in water after a recent rain, bare foot. Once I removed my shoes and stood in the water I could feel it too.
I got out my multi-meter and sure enough got 15 volts A/C showing when I touch bare metal on the framework of the RV, and drop the other end into the puddle on the ground.
Haven't had time to do much troubleshooting yet and am at work now so looking for suggestions for when I get home. My only thoughts are to turn off the circuits one at a time and try to narrow it down to an area, but not sure if that will work. None of the breakers is tripped and none of the GFCI's are tripped. I have one of those plug-in circuit testers with the 2 orange lights and 1 red light that test for polarity and it shows good (two yellow lights) wherever I've plugged it in. Most all of the electrical outlets look to be those fast connect type that are mounted in wood paneling like under cabinets so they don't ground at the outlet point but back in the circuit breaker panel.
Could this be a problem with the power pole, or stray voltage going through insulation but too close to metal? The RV is 2 years old so out of warranty.
Any ideas would be appreciated.
Seeking Advice
  • Mike_Sokol's avatar
    Mike_Sokol
    Explorer
    Jul 06, 2015
    rekoj71 wrote:
    I'm just not sure if the heating elements are the same type or not. The ones I remember for a 40~ gal tank were more of a loop and the camco one is more of a single straight rod, but I don't personally know what rod or element type the other posters were referring to. I'm not sure what the water heater you linked to has either. Hoping others who know more about RV factory electric water heaters chime in cause mine is primarily a gas unit with the electrical kit added later.

    For this test the shape of the heating element doesn't matter. There will be slightly different measurements depending on if the element goes dead short to the tube, or the hermetically sealed tube leaks due to corrosion. But in neither case will it create a hot-skin condition unless there's also a high resistance safety ground somewhere between the RV and the incoming service panel. That's what I want to demonstrate beyond all doubt.

    Mike Sokol
    No~Shock~Zone
  • NJRVer's avatar
    NJRVer
    Explorer
    Jul 06, 2015
    NJRVer wrote:
    NJRVer wrote:
    Mike_Sokol wrote:
    Would something like this electric water heater be good enough for this demonstration? HW I don't really need an LP/Electric water heater for anything, so this electric-only version should be good enough for a proof-of-concept setup. But all of you need to agree that it's sufficiently close to what you're using in your own RVs.

    I'm serious about doing a demonstration to disprove this old-wives-tale. Here's a link to my portable test bench where I demonstrate electrical grounding safety for musicians and big sound systems. B&K

    I welcome any comments or suggestions on what you all would like to see.



    In all fairness, for the test to be accurate it should be with an rv hw heater in an rv.
    I will see what brand hw heater I have tomorrow.


    My hw heater is a Suburban
  • NJRVer's avatar
    NJRVer
    Explorer
    Jul 06, 2015
    NJRVer wrote:
    Mike_Sokol wrote:
    Would something like this electric water heater be good enough for this demonstration? HW I don't really need an LP/Electric water heater for anything, so this electric-only version should be good enough for a proof-of-concept setup. But all of you need to agree that it's sufficiently close to what you're using in your own RVs.

    I'm serious about doing a demonstration to disprove this old-wives-tale. Here's a link to my portable test bench where I demonstrate electrical grounding safety for musicians and big sound systems. B&K

    I welcome any comments or suggestions on what you all would like to see.



    In all fairness, for the test to be accurate it should be with an rv hw heater in an rv.
    I will see what brand hw heater I have tomorrow.
  • NJRVer's avatar
    NJRVer
    Explorer
    Jul 06, 2015
    Mike_Sokol wrote:
    Would something like this electric water heater be good enough for this demonstration? HW I don't really need an LP/Electric water heater for anything, so this electric-only version should be good enough for a proof-of-concept setup. But all of you need to agree that it's sufficiently close to what you're using in your own RVs.

    I'm serious about doing a demonstration to disprove this old-wives-tale. Here's a link to my portable test bench where I demonstrate electrical grounding safety for musicians and big sound systems. B&K

    I welcome any comments or suggestions on what you all would like to see.



    In all fairness, for the test to be accurate it should be with an rv hw heater in an rv.
  • rekoj71's avatar
    rekoj71
    Explorer
    Jul 06, 2015
    I'm just not sure if the heating elements are the same type or not. The ones I remember for a 40~ gal tank were more of a loop and the camco one is more of a single straight rod, but I don't personally know what rod or element type the other posters were referring to. I'm not sure what the water heater you linked to has either. Hoping others who know more about RV factory electric water heaters chime in cause mine is primarily a gas unit with the electrical kit added later.
  • Mike_Sokol's avatar
    Mike_Sokol
    Explorer
    Jul 06, 2015
    rekoj71 wrote:
    I think an RV water heater test could probably be done by just getting the camco electric water heater conversion kit. It's just a heater rod and all of the electrical connectors to hook it up to a l.p. heater by sticking it into the drain plug, but this test could probably be done by just plugging the rod in and seeing if it could melt enough to cause a short circuit. Someone else might know more about the rods that are having the problems though.
    My kit was only about $75. I haven't had a problem with it yet but I haven't had my water heater empty since i've gotten my RV.

    I've already done this experiment using stock 120 volts electric water heater elements from Home Depot. But this was just the elements suspended in water inside of a plastic bottle so I could collect hydrogen and oxygen which is a natural product of electrolysis with fresh water, or Hydrogen Sulfide gas with chlorinated water (I think). So while I'm sure of my declaration that a properly grounded RV with a hot water heater having a failed element cannot cause a hot skin if the EGC ground is intact, I need to cone up with a plausable demonstration that shows that this is true without a doubt. I think I need a tank with a heater element, then recreate a variety of grounding situations to demonstrate how this actually works.

    Mike Sokol
  • rekoj71's avatar
    rekoj71
    Explorer
    Jul 06, 2015
    I think an RV water heater test could probably be done by just getting the camco electric water heater conversion kit. It's just a heater rod and all of the electrical connectors to hook it up to a l.p. heater by sticking it into the drain plug, but this test could probably be done by just plugging the rod in and seeing if it could melt enough to cause a short circuit. Someone else might know more about the rods that are having the problems though.
    My kit was only about $75. I haven't had a problem with it yet but I haven't had my water heater empty since i've gotten my RV.
  • rekoj71's avatar
    rekoj71
    Explorer
    Jul 05, 2015
    I had to work again and didn't get as much free time today, but I did get a chance to show the office guys the voltage I was reading off of the outside of the pedestal to the dirt and he was quite surprised and put it first on the list for the maintenance man (a former electrician) to look at tomorrow. I poured a cup of water on the ground where I put my black lead into the dirt trying to get a better ground and got about 10V.
    The fun part cam when I showed him I had about 5V comming from my RV even when I had all of my electrical disconnected and turned off. He suggested I use the jumper cables I still had out from yesterday and clip it to the water pipe that was also right there and see if it would help ground my RV. Thought it might be worth a shot but then had an idea and tried to test the spigot to see if maybe since the water pipe was right next to the pedestal if maybe someone might have already hooked a ground to the pipe and sure enough the water pipe had 6V on it. So I disconnected the hose from my RV and the voltage from my still unplugged and now waterless RV was now less than a volt. :)
    Finally think I found the source of the problem. Even when testing from the back of the pedestal and using the water pipe for a ground instead of the dirt the voltage only shows about 5V, which makes sense as in Mike's website he explained that a volt meter only measures voltage differences, and that was about the difference in voltage of those two items.
    It will be interesting to see what the electricians find tomorrow.
  • Mike_Sokol's avatar
    Mike_Sokol
    Explorer
    Jul 05, 2015
    Would something like this electric water heater be good enough for this demonstration? HW I don't really need an LP/Electric water heater for anything, so this electric-only version should be good enough for a proof-of-concept setup. But all of you need to agree that it's sufficiently close to what you're using in your own RVs.

    I'm serious about doing a demonstration to disprove this old-wives-tale. Here's a link to my portable test bench where I demonstrate electrical grounding safety for musicians and big sound systems. B&K

    I welcome any comments or suggestions on what you all would like to see.
  • Mike_Sokol's avatar
    Mike_Sokol
    Explorer
    Jul 05, 2015

    I have run into this 3 times now on different RV's. In every one when the water heater breaker was turned off, no more hot skin. In all 3 the element had been dry powered and melted. The water heaters all had good grounds connected but there was still power getting to the chassis.

    This is an old-wives tale I've heard for years, but which has no basis in fact. While casual observation might suggest that a melted element in a HW heater by itself can cause a hot-skin condition, in reality there must also be an open or high-impedance path in the EGC ground connection for any appreciable (more than 1 volt) to occur on the RV skin. This is my Mechanical, Electrical and Power Distro Engineering background(s) of over 40 years talking. In fact, I've set up similar experiments in my backyard using corroded and shorted HW heater elements to observe fault current and hydrogen gas production in fail mode. However, a compromised ground in an RV due to corrosion, broken ground pin, or even an missing or loose bonding screw for the G-N bond at the service panel would make it act like you describe, especially if a local ground rod alone was the only way the RV was being "grounded". In that case there will typically be 1 or 2 amperes of ground fault current flowing through the broken/shorted heater element to the chassis of the RV. This could create a hot-skin voltage and current if there was a local-only ground rod, but not with a proper EGC connection back to the service panel.

    However, I know that it's hard to believe me without a real world mock-up and demonstration of the situation. This would make a great video to debunk that myth, wouldn't it? I'll see if a HW heater manufacturer who sells to the RV market will send me a hot water tank with some extra heating elements to burn up for the experiment. Do you have any suggestions of HW heater brands and models that are typical. Does the forum moderator have any manufacturer contacts they can suggest?

    Mike Sokol
    No~Shock~Zone

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