Stray voltage

[Mr Lars]

Went to open the door this morning on the TT, and felt a tingling when I grabbed the door latch. Went got my multi meter, set of for 250v AC, stuck the black terminal thingy down into the dirt(damp), and touched the red one on the chassis of the TT and the needle jumped up to 120 volts.
Took my outlet tester into the garage where the extension cord is plugged into(120v 20amp), indicating normal.
Somehow there is 120 volts making its way to the TT frame.
Will have to find my pair of rubber coated gloves, then get inside to test outlets inside.

 

[Isaac-1]

Try turning off the breakers on the RV outlets one at a time, and retest, this will isolate if it is in the internal outlet wiring, or if it is in the main wire going into the trailer

 

[Gary RV_Wizard]

We wish you a quickly successful hunt!

Suggest you start by flipping all the breakers off. If there is still voltage to earth ground, the ground fault is in the supply prior to the load center. If no voltage to earth ground, turn the breakers on one at a time until the voltage reappears. That should quickly narrow the search. Note that it is not necessarily associated with an outlet - could be a hardwired appliance such as water heater or converter/charger.

 

[Kirk]

Are you sure that you do not have the polarity reversed somewhere? It has be reversed somewhere as a short to ground would trip the circuit breaker. And don't forget to pull the power plug before you go to open the RV door!

 

[Mr Lars]

Well, it’s definitely some sort of ground fault in the garage. I flipped all the breakers off, plugged the cord back in to the garage outlet, and still have 120v thru the TT frame.
I then plugged into an outlet inside the house, the 120v thru the TT frame disappeared.
The strange thing is, I can plug my outlet tester in(any of the garage outlets) shows normal, when I plug the TT into the outlet right next to the tester, then it indicates open ground.

 

[Kirk]

I would open that outlet box next that look at the outlet and it's connections. It may be as simple as replacing the outlet. If you do that, don't use the cheapest ones.

 

[cwilt]

Have you tried a different extension cord?

I had a buddy who had a similar issue and it was his extension cord.

 

[Rene T]

Have you tried a different extension cord?

I had a buddy who had a similar issue and it was his extension cord.

The OP said he plugs his extension cord in the garage and he has the problem. He plugs it into the house at a different outlet and it is fine. Sounds like the cord is fine. I’m assuming he is using the same extension cord.

 

[cwilt]

The OP said he plugs his extension cord in the garage and he has the problem. He plugs it into the house at a different outlet and it is fine. Sounds like the cord is fine. I’m assuming he is using the same extension cord.

Yeah, moving it around could open or close the short/open.

 

[Rene T]

Yeah, moving it around could open or close the short/open.

That’s true.

 

[Mr Lars]

Have you tried a different extension cord?

I had a buddy who had a similar issue and it was his extension cord.

Just changed cords, still the same.

 

[Mr Lars]

Chances are, there is a break in the rigid conduit, unfortunately it’s behind plywood walls. Guess I will try and fish thru ground wire from breaker box to the outlets, thankfully most are in a straight line around the walls.

 

[Mr Lars]

But that still does not answer the issue of the 120v current getting to the TT frame.

 

[Isaac-1]

If the ground pin on the outlet is live it could allow voltage to get to the trailer frame

 

[bigb56]

A reverse polarity with a bootleg ground will do, an open neutral with a bootleg ground will do it as well as a short to unbonded conduit. Plug the extension cord into the good outlet, carry the other end over to the garage outlet and measure voltages between all 3 of the garage outlet holes to the extension cord ground.

How is your garage set up for power? Does it have a sub panel? This can also happen when a 3 wire sub panel is G-N bonded and the main neutral opens, or when conduit is used for the EGC and neutrals get put on the wrong bus and the conduit separates.

 

[Mr Lars]

The garage is powered with a sub panel. The garage is detached from the house.

 

[bigb56]

The garage is powered with a sub panel. The garage is detached from the house.

Proceed with caution. There are a couple of possible scenarios here, both deadly.

If you have an open or compromised neutral to that sub panel, and the ground wires are bonded to the neutral in that panel, you are going to have neutral current energizing the grounding system in the garage which includes all your outlet ground holes and everything plugged into them, your metal light fixtures, your conduits and even your ground rods if present. The electric panel cabinet itself will also be energized.

The second scenario is the grounding system in the garage is not bonded to the neutral but only to a ground rod(s) and a hot wire is shorted to the grounding system. The entire grounding system as I described above will again be energized with line current and the breaker will never trip because a ground rod can't carry enough current to make it trip.

If you have metal plumbing out there it can be energized as well.

Time to take some measurements or call in someone if you're not 100% qualified to do this safely.

 

[woof-n]

My first guess is that somewhere the neutral and ground was reversed from a recent repair or installation.

The neutral carrys the unbalanced load of 120V back to the source.

The ground wire is for personal protection. If the feed shorts to ground, the breaker should trip to protect people.

The earth ground is for lighting protection. It is not intended to be a path back to the source ( city power) but it indirectly can travel through the damp soil/concrete back up through to the ground rod to the panel.

We have all been taught that electricity takes the path of least resistance. NOT True!!! it takes all paths.

If the neutral and the ground, get tied together anywhere before its trip back to the source (city power). Both the neutral and ALL ground wires will carry the unbalanced load back the source. ALL grounds will become current carrying conductors. If you touch anything grounded and have contact with an earth ground, you will feel the current. Why, because electricity takes all paths back to the source.
Good luck Please let us know what you find

 

[John From Detroit]

Are you sure that you do not have the polarity reversed somewhere? It has be reversed somewhere as a short to ground would trip the circuit breaker. And don't forget to pull the power plug before you go to open the RV door!

Last trailer I had the prior owner made his own 20 Amp adapter and reversed black and white.

 

[Heli_av8tor]

We have all been taught that electricity takes the path of least resistance. NOT True!!! it takes all paths.

WOW! Someone finally said it. I cringe every time I hear "electricity takes the path of least resistance". It's often proclaimed even by people who should know better. Fighting that "common knowledge" is a very steep uphill climb.