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Old 09-17-2018, 04:13 PM   #1
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Shell Shock

Last week camping I was experiencing low voltage shock while touching the camper outside while barefoot. While hooked to shore power turned off main breaker and still felt the shock. When I got home and access to multimeter I have 8 ohms between the ground pin and what I suspect to be neutral (upper right pin). So before I start getting into the breaker panel am I correct in stating they shoudn't be connected in any way. I never noticed this before but not sure if I was ever barefoot outside before. We've had are 27 FC for 14 mouths.
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Old 09-17-2018, 05:16 PM   #2
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7 Pin Connector

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Originally Posted by Tbuck View Post
... I have 8 ohms between the ground pin and what I suspect to be neutral (upper right pin). ...
Are you talking about the 7 Pin Plug (Umbilical)? From the diagram (trailer end), the upper right pin is the brake lights/running lights.

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Old 09-17-2018, 05:37 PM   #3
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No the 30 amp connection for 120
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Old 09-17-2018, 05:47 PM   #4
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Sounds like an "open" neutral in the power cord.
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Old 09-17-2018, 06:03 PM   #5
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No the 30 amp connection for 120
The only place in AC wiring where the ground and neutral meet is in the source main breaker panel (your house).
So a reading of 8 ohms does not surprise me.
Turn off breakers at the converter, one at a time and see if the shock stops.

I chased a light shock in my home and it turned out to be a surge power strip where neutral and hot showed reversed.
I'd buy one of those inexpensive circuit testers at the big box store and start looking into every outlet and see if you can narrow it down. You can add a cheap 15 amp to 30 amp adaptor and you can test the 30 amp outlet too.
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Old 09-17-2018, 06:15 PM   #6
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Camper not connected to any power, parked in barn.
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Old 09-17-2018, 06:27 PM   #7
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A short in the 12-volt system?

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Old 09-17-2018, 08:24 PM   #8
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Do you have an inverter in the coach?
12 volts typically will not shock anyone.
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Old 09-17-2018, 09:02 PM   #9
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If I understand correctly you got a shock when shore power was connected, and you measured 8 ohms between ground and neutral when it was not.


Ground is not at the same potential everywhere. If the power at your campsite was up to code as I read it, the green ground wire is connected to a ground rod at the main breaker panel or the meter. If there was leakage to ground somewhere near your trailer, it is possible to feel a shock as current will flow from that leakage source through you to the shell which should be connected to the green wire ground and back to the ground at the power panel.


But the leakage may be in your trailer. You should read infinite ohms between neutral and ground (and between hot and ground) with no shore power connected.


The only way to ensure no shock from the trailer skin to ground is to drive a ground rod at your campsite and connect it to the shell. Or wear shoes.....


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Old 09-17-2018, 10:09 PM   #10
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Last post by OP: [#6]

Quote:
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Camper not connected to any power, parked in barn.
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Old 09-17-2018, 10:10 PM   #11
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Do you have an inverter in the coach?
12 volts typically will not shock anyone.
A short from the inverter's output?

Re: 12-volt shock -- maybe under these limited conditions barefoot?

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Originally Posted by Tbuck View Post
Last week camping I was experiencing low voltage shock while touching the camper outside while barefoot.
. . .
I never noticed this before but not sure if I was ever barefoot outside before.
. . .
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Old 09-17-2018, 10:18 PM   #12
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Camper not connected to any power, parked in barn.
Do you still get the shock if you put the Use/Store switch on Store?

How about turning off the inverter on its front or back panel, or flipping off the 12-volt circuit breaker for the circuit which feeds the inverter?

Any difference?
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Old 09-17-2018, 10:57 PM   #13
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Quote:
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Last post by OP: [#6]
I think that was a response to post#5. The only mention of a shock was in post 1, while connected.

With few exceptions for high power RF, the only way to get a shock is to be in one side of a complete circuit. So the op is one side of the circuit from the shell to ground. The other side of the circuit must be from the shell to something else and back to ground or from ground to something else that has voltage with respect to ground. The trick is figuring out what something else is. If something in the trailer is leaking from hot to ground (one possibility is a line filter in an AC powered device like the fridge, AC, or converter), then op could feel a shock. These filters typically have capacitors from hot and neutral to ground. The two capacitors form a voltage divider that put roughly 50 volts on the ground wire but it is supposedly bonded to neutral at the power entrance so there should be very low potential on the shell.

My two favorite possible causes for the shock are broken bond between the shell and the green wire safety ground and whatever is causing the 8 ohm reading between ground and neutral.

Find the 8ohm source and fix it. Measure the resistance between the shell and green wire ground in the trailer with shore power disconnected. It should be very low.



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Old 09-17-2018, 11:54 PM   #14
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If your coach is not plugged in to shore power there is no connection to the ground in the main panel.
Since the tires serve as somewhat of an insulator. No connection to the earth. Other than the tongue jack. If the tongue jack is on wooden blocks. It is more or less insulated from the earth.
If the stabilizers are down on insulated pads. Or not down at all. No connection to earth.
What voltage do you read from the shell to the dirt? Or pavement below the coach.
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