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Open Roads Forum  >  General RVing Issues

 > RV Hot Skin (Exterior electrification)

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Mike134

Elgin, IL

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Posted: 07/22/21 10:15am Link  |  Print  |  Notify Moderator

sgtsteve wrote:

Thanks to all who have written on the topic!

I had an electrician come out and test the outlet the trailer was plugged into. The result was there is a proper ground in the outlet. On another note, when the "electrification" occurred, no circuit breaker was thrown, not in the house and not in the trailer.


Just an FYI Whenever there is an electrocution fatality the breaker never trips. It's not designed for that type of protection.

Keep in mind when working on this 100 milliamps will kill you.
Another words 0.1 amps. Do you have the necessary skills? Based on some of the answers I saw in this thread those folks providing the answers don't either.


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time2roll

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Posted: 07/22/21 10:24am Link  |  Print  |  Notify Moderator

sgtsteve wrote:

Thanks to all who have written on the topic!

I had an electrician come out and test the outlet the trailer was plugged into. The result was there is a proper ground in the outlet.
Did he also use the 3-light tester in the RV when plugged in with the same series of adapters?
Hopefully he also checked polarity.


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CA Traveler

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Posted: 07/22/21 10:32am Link  |  Print  |  Notify Moderator

Mike134 wrote:

Just an FYI Whenever there is an electrocution fatality the breaker never trips. It's not designed for that type of protection.

Keep in mind when working on this 100 milliamps will kill you.
Another words 0.1 amps. Do you have the necessary skills? Based on some of the answers I saw in this thread those folks providing the answers don't either.
Or maybe even less. GFCIs trip at about 5 millamps or 0.005 amps. That's a very small ground fault (ie the amp leakage to ground).


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Mike134

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Posted: 07/22/21 10:43am Link  |  Print  |  Notify Moderator

CA Traveler wrote:

Mike134 wrote:

Just an FYI Whenever there is an electrocution fatality the breaker never trips. It's not designed for that type of protection.

Keep in mind when working on this 100 milliamps will kill you.
Another words 0.1 amps. Do you have the necessary skills? Based on some of the answers I saw in this thread those folks providing the answers don't either.
Or maybe even less. GFCIs trip at about 5 millamps or 0.005 amps. That's a very small ground fault (ie the amp leakage to ground).


Your correct 5 milliamps is their deigned trip point, some folks can't even feel it. 20 milliamps will cause you to be unable to release your grip, then as your skin breaks down more current will flow till your heart goes into an irregular heartbeat. In the case of the Op's wife her muscles fortunately contracted violently enough to throw her clear.

Mike134

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Posted: 07/22/21 10:56am Link  |  Print  |  Notify Moderator

All this talk about grounding thought I'd better check my own system including any adapters I put in the grounding "chain". Zero ohms is the correct answer[image]

Gdetrailer

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Posted: 07/22/21 12:46pm Link  |  Print  |  Notify Moderator

Mike134 wrote:

enblethen wrote:


Some leakage could be induced into the skin and chassis.


That's a new one on me after 38 years.


Its called "capacitive leakage current".

SEE HERE

"In any electrical installation, some current will flow through the protective ground conductor to ground. This is usually called leakage current. Leakage current most commonly flows in the insulation surrounding conductors and in the filters protecting electronic equipment around the home or office. So what's the problem? On circuits protected by GFCIs (Ground Fault Current Interrupters), leakage current can cause unnecessary and intermittent tripping. In extreme cases, it can cause a rise in voltage on accessible conductive parts.

The causes of leakage current

Insulation has both electrical resistance and capacitance - and it conducts current through both paths. Given the high resistance of insulation, very little current should actually leak. But -- if the insulation is old or damaged, the resistance is lower and substantial current may flow. Additionally, longer conductors have a higher capacitance, causing more leakage current. That's why GFCI breaker manufacturers recommend one-way feeder length be limited to 250 feet, maximum.

Electronic equipment, meanwhile, contains filters designed to protect against voltage surges and other disruptions. These filters typically have capacitors on the input, which adds to the overall capacitance of the wiring system and the overall level of leakage current.

"


Typically, as long as all electrical wiring involved including outlets, adapters, extension cords are in good shape and wired properly any voltage developed on the safety ground wire will be zero or near zero at all times.

If the wiring on the safety ground is not present or there is substantial resistance at any connection. Or way too much wire involved from the main breaker panel in the home (where ground and neutral are bonded with the home's entrance panel grounding system) or a fault in the entrance panels safety grounding system it is very possible for enough capacitive leakage current to develop considerable voltage on the "skin" of the RV, enough to give you a good buzz.

Many yrs ago, I remember my Uncle who built a shop, DIYed his panel to the shop and had PoCo connect on to his panel.. Kept complaining everytime on damp days he would get jabbed.. My Dad discovered, my Uncle instead of planting a ground rod or two, just ran the entrance ground wire out and a couple of inches down and out a couple of feet from the building in clay..

His breaker panel was using mainly the PoCos nuetral wire as ground!

A couple of ground rods and wire fixed the leakage..

OPs electrician should have checked and verified that the service entrance panels grounding system is connected and verified zero volts showing anywhere in the house wiring.

OPs electrician should have checked and verified that when the trailer was plugged in that the ground through all adapters and extensions is good and zero volts showing.

OP should have had the electrician check and verify the ground wire from the RV cable into the breaker panel in the RV is in good working order. The breaker panel in a RV is treated as a sub panel of the home so grounds must attach to a ground buss bar and neutrals must attach to neutral buss bar which is electrically isolated from the safety ground.

Because RVs move about, sometimes the connections in the breaker panel get loose, so those connections need to be checked.

OPs garage outlet should have GFCI by today's standards but if it was built before GFCIs were required that is grandfathered unless you remodel the garage electrical system..

Adding a GFCI isn't a bad thing, but in reality if the fault is in the RV electrical system that fault will need to be found and fixed.. Reason being is 30A and 50A shore power panels in campgrounds will not have GFCI on them.

OP could have combo issue, poor grounding combined with one of several possible faults like failed water heater electric heating element, failed/leaky fridge heating element, faulty power converter or leakage from the AC unit.

To troubleshoot the RV circuits, you can turn off a breaker one at a time to see if the voltage on the ground goes away. Once you find a circuit that removes the voltage when the breaker is off you now have narrowed down to one circuit and whatever is on that circuit.

BB_TX

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Posted: 07/22/21 01:51pm Link  |  Print  |  Notify Moderator

time2roll wrote:

sgtsteve wrote:

Thanks to all who have written on the topic!

I had an electrician come out and test the outlet the trailer was plugged into. The result was there is a proper ground in the outlet.
Did he also use the 3-light tester in the RV when plugged in with the same series of adapters?
Hopefully he also checked polarity.

Yes. The big question, is there a proper ground at the outlets INSIDE the trailer. He would be short of an adequate test if he didn’t check that.

wopachop

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Posted: 07/23/21 05:43pm Link  |  Print  |  Notify Moderator

That was a lot of info. Mike can you explain your picture please? I guess the 120v ground is tied into the trailer frame?

If thats the case, could your test show zero ohms but once plugged in there could be a hot wire touching the frame? Trying to think how that would work. Could the person not get shocked, but there is still a hot wire touching the frame? Assuming youre not plugged into a gfci.

I want to test my own trailer next time im home. Plug the trailer in. Set meter to AC volts, and then probe the outlets between hot and ground? I can also test the ohms between all the adapters and the trailer frame.

Mike134

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Posted: 07/23/21 06:24pm Link  |  Print  |  Notify Moderator

Mike134 wrote:

wopachop wrote:

That was a lot of info. Mike can you explain your picture please? I guess the 120v ground is tied into the trailer frame? yes it should be.

If thats the case, could your test show zero ohms but once plugged in there could be a hot wire touching the frame?No because if you had a good ground connection you would trip the circuit breaker on the circuit touching the metal frame Trying to think how that would work. Could the person not get shocked, but there is still a hot wire touching the frame? yes for example linemen wearing rubber boots and gloves to keep them insulated from "ground" when they work live circuitsAssuming youre not plugged into a gfci.

I want to test my own trailer next time im home. Plug the trailer in. Set meter to AC volts, and then probe the outlets between hot and ground? I can also test the ohms between all the adapters and the trailer frame.


First and foremost before doing anything else check for zero ohms between the ground pin on your adapter like I did and bare metal of the trailer. Then check between the ground slot of a trailer outlet and that same plug's ground pin. Again ZERO ohms is the value you're looking for. Your wife was shocked because the trailer was not grounded and that can be caused by a host of reasons as previous posts have discribed. Once you fix the ground problem then finding the wire causing the "hot frame" will be easier.
Just want to add all this testing is done with the trailer UNPLUGGED from any power source. Let us know what you find out about the grounding


wopachop

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Posted: 07/23/21 06:26pm Link  |  Print  |  Notify Moderator

Good stuff thanks.
So for anyone following along you want to set your meter to ohms. (horseshoe lookin thing) Then touch the probes between 2 spots.
1. The extension cord ground pin and the trailer frame.
2. The extension cord ground pin and the ground slot of an outlet. If you have an exterior outlet drag the extension cord over to that location. Also remember to find bare metal or touch the head of a bolt that goes into the frame like it appears Mike is doing.

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