Can't Seem To Fix Hot Skin Problem

[Oldguy001]

We had a professional RV Heating & Cooling company come out and install a second A/C unit in the bedroom of our 2023 Transend Xplor 231RK Travel Trailer. Unfortunately, this was not prewired as it apparently is in some models, but he used the power source from the ceiling outlet where the TV would go, A few days later, I climbed under the unit to tighten something and I got shocked when I touched an aluminum bracket. I asked the A/C man to come back out and check his work, which all seemed to be fine, and after checking several things in the trailer, he determined that the line between the shore line connection and the breaker box must have been breached at some point, because even with the Main Breaker off, we still had "Hot Skin". Typically between 30 to 45 amps everywhere on the outside of the camper. I have read extensively about this problem and its causes, and I have tried virtually everything I could think of, including installing a new main power receptacle connected to the existing breaker box in the trailer, checked all the wires between the house breaker box and the shore line outlet, put a new male end on the extension cord, unhooked the positive terminal to the battery, but nothing seems to change. And the really perplexing part is that even with the main breaker in the camper in the off position, the outside skin, screws, windows, etc. are still going beep, beep with a Non-Contact voltage tester.
If anybody has any advice, I would really appreciate it.
Thank you in advance,
Lee

[TucsonJim]

Wow, that's a tough one. Are you still under warranty? If so, it might be worth contacting GDRV customer servicer to discuss the situation with them. They may say that you're responsible if the modifications wind up being the cause. But if it were me, I'd gladly pay the price for repairs to fix the safety issue.

Curiosity question. If you disconnect from shore power, is there any resistance reading from the hot side of the shore power input to the frame?

You can call GDR customer service at 574-825-9679.

Jim

[Jkwilson]

What kind of cords are being used to hook this up?

True hot skin is so exceedingly rare that it almost never happens. It requires two unrelated failures.

You almost certainly have a missing ground connection. From outlet to trailer, measure voltage between the ground pin and the hot pin on cords. It should always be 120V.

[Oldguy001]

Thanks for the reply, TucsonJim. Our warranty ran out in September. You know, Murphy's Law and all that. But I will definitely get in touch with customer service to see what they say.
Lee

[Oldguy001]

Thank you, JKwilson. I will go check that now. The cord is a standard 30amp that came with the unit.
Lee

[ncitro]

Oldguy001 Does the oriel follow you from park to park as you move?

[howson]

We had a professional RV Heating & Cooling company come out and install a second A/C unit in the bedroom of our 2023 Transend Xplor 231RK Travel Trailer. Unfortunately, this was not prewired as it apparently is in some models, but he used the power source from the ceiling outlet where the TV would go, A few days later, I climbed under the unit to tighten something and I got shocked when I touched an aluminum bracket. I asked the A/C man to come back out and check his work, which all seemed to be fine, and after checking several things in the trailer, he determined that the line between the shore line connection and the breaker box must have been breached at some point, because even with the Main Breaker off, we still had "Hot Skin". Typically between 30 to 45 amps everywhere on the outside of the camper. I have read extensively about this problem and its causes, and I have tried virtually everything I could think of, including installing a new main power receptacle connected to the existing breaker box in the trailer, checked all the wires between the house breaker box and the shore line outlet, put a new male end on the extension cord, unhooked the positive terminal to the battery, but nothing seems to change. And the really perplexing part is that even with the main breaker in the camper in the off position, the outside skin, screws, windows, etc. are still going beep, beep with a Non-Contact voltage tester.
If anybody has any advice, I would really appreciate it.
Thank you in advance,
Lee

Lee,
A typical cause of a hot skin is reverse-polarity. Have you specifically measured the 120V voltage at the outlet?

From Mike Sokol's NoShockZone website (see https://www.rvtravel.com/rv-electric...ting-rvt-1036/ for a full article on testing):



So using your multimeter, there should be 120vAC between

• HOT and NEUTRAL
• HOT and GROUND

There should NOT be any voltage between NEUTRAL and GROUND

Video here on how to test: https://www.rvtravel.com/rv-electric...yt/Fd9ghgw9o8I

Have you done these specific tests yourself to confirm the outlet supplying power to the RV is wired correctly.?

Howard

[Jlawles2]

Continuing with Howard's information above, as the condition happened after the AC install, verify that the AC man did not reverse the polarity of the hot and neutral feeding the new unit. this could create the issue you are having.

[Jkwilson]

Continuing with Howard's information above, as the condition happened after the AC install, verify that the AC man did not reverse the polarity of the hot and neutral feeding the new unit. this could create the issue you are having.

Reversing hot and neutral in the unit or even in the outlet or cord feeding the trailer won’t change the voltage of the frame of the RV. That’s fixed at ground voltage by the ECG from the panel.

[Cate&Rob]

Has all this been happening while plugged into the same shorepower outlet? Perhaps the problem is upstream of your cord and RV?
FWIW . . . at a National Rally a few years back we had a whole row of RVs with hot skins . . . caused by the supply circuit.
Running two ACs off a single 30A circuit would be a stretch (which is why your Transcend is not wired for the second AC). Were any changes made to the supply?

Rob

[TedS]

Check continuity on the trailer. Measure at the trailer inlet receptacle. There should be no continuity neutral to ground or hot to ground. There should be continuity ground to chassis. Neutral should be bonded to ground only at the power source.

[TucsonJim]

Oldguy001 - Lee

Where are you located. There are several forum members that could help with troubleshooting this issue if you're close by. If you're in Tucson, I'd be happy to help.

Jim

[howson]

Reversing hot and neutral in the unit or even in the outlet or cord feeding the trailer won’t change the voltage of the frame of the RV. That’s fixed at ground voltage by the ECG from the panel.

John -- can you elaborate for this non-electrician? I have no idea what "ECG" is referencing.

The info I posted was paraphrased from what I think I understood reading Mike Sokol's RV Electrical Safety book. Mike states in chapter 4 (topic is "Hot Skin") that reverse polarity and ground issues are the two usual causes of a hot-skin condition.

An RV Hot-Skin condition occurs when the frame of the vehicle is no longer at the same voltage potential as the earth around it. This is usually due to an improper power plug connection at a campsite or garage AC outlet. Now to be honest, I think the majority of campgrounds have properly wired and maintained power pedestals, but certainly there are instances where a campsite has outlets with reversed polarity or improper grounding. -Mike Sokol, RV Electrical Safety, Chapter 4 p.40

From my understanding, an RV with an issue that connects into the same branch (in a campground) can cause a problem in everyone's camper (that are on the same circuit).

I'm missing something between what I'm reading in Mike's book and your inputs (due to my lack of understanding or how I'm interpreting what I'm reading).

Howard

[TedS]

Here is Sokol's part 2 hot skin troubleshooting.
https://rvelectricity.substack.com/p...roubleshooting

EGC is electrical grounding conductor. Also know as ground wire in the power cable and/or ground connection inside the trailer.

[Jkwilson]

John -- can you elaborate for this non-electrician? I have no idea what "ECG" is referencing.

The info I posted was paraphrased from what I think I understood reading Mike Sokol's RV Electrical Safety book. Mike states in chapter 4 (topic is "Hot Skin") that reverse polarity and ground issues are the two usual causes of a hot-skin condition.

An RV Hot-Skin condition occurs when the frame of the vehicle is no longer at the same voltage potential as the earth around it. This is usually due to an improper power plug connection at a campsite or garage AC outlet. Now to be honest, I think the majority of campgrounds have properly wired and maintained power pedestals, but certainly there are instances where a campsite has outlets with reversed polarity or improper grounding. -Mike Sokol, RV Electrical Safety, Chapter 4 p.40

From my understanding, an RV with an issue that connects into the same branch (in a campground) can cause a problem in everyone's camper (that are on the same circuit).

I'm missing something between what I'm reading in Mike's book and your inputs (due to my lack of understanding or how I'm interpreting what I'm reading).

Howard

With everything wired properly, the ECG is tied to the same point as the neutral at the service panel, and those two are connected to an electrode so the soil near the panel and the neutral and ground are all at the same voltage. At the RV, the frame is tied to the ECG, so it’s still very close to the same voltage as the neutral. If you touch the frame and the neutral, you won’t be shocked, but if you touch the frame and hot, you will be. But neither hot or neutral is is out and exposed for people to touch unless they open something up. If a hot wire went bad and contacted the frame, the breaker would trip. If a neutral wire went bad and touched the frame, nothing as far as letting a person get shocked will happen.

The above is true even if hot and neutral were switched inside the trailer, you’d still have to get inside of something to get shocked.

So in order to be shocked by touching the frame, you’d have to be touching something else at a different voltage. What is around that you are likely to touch when you touch the frame? The soil under your feet. The grounding electrode is often a long way from a campsite or parking spot. Stray current from the utility grid and the resistance of the soil play together to cause the soil to be at a significantly different voltage than the soil at the service panel, meaning that the frame of the RV can be at a different voltage than the soil underneath causing you to feel a small shock when touching both.

If an RV in a campground has a ground/neutral bond inside, current will flow in the ground conductor and you can see bigger voltage changes in the frames of RVs in the same area being fed by the same service panel so there are many more opportunities for people to feel the difference.

Most commonly, the problem is a missing ground connection in the cable or pedestal for the RV