Another case of Hot Skin

GolfingDebby · 06-15-2016, 02:36 PM

We are experiencing 118 volt hot skin on my sister's 2619 measured with a volt meter when connected to an improperly grounded receptacle. When connected to a properly grounded receptacle the hot skin condition is not present. It is my understanding that connecting to a properly grounded receptacle just provides a ground thereby eliminating the condition, but does not address the fundamental cause for the hot skin. I would think there must be a short somewhere in the trailer wiring causing this condition. All receptacles in the trailer are wired correctly. Any ideas where to start looking?

Thanks, Doug

**Bill** · 06-15-2016, 06:53 PM

Doug -

While it is possible to produce a hot skin by miswiring the trailer, it is much more likely that the cause is an improperly wired household outlet that is feeding the trailer, or a miswired 15amp-to-30amp adapter.

We need quite a bit more info about what you are doing and seeing. You say that you are experiencing the hot skin when the trailer is plugged into an "improperly grounded receptacle". In what sense is it improperly grounded? Is the ground actually missing? If so, how are you sure that the remaining two conductors, hot and neutral, are not reversed? Is the outlet a two-prong outlet, and you are using a 3-to-2 adapter?

Tell me more about the properly-grounded receptacle. What do you mean by "properly grounded", and how do you know that the other two conductors (hot and neutral) are not reversed?

Since the TM power cord has a 30-amp plug, how are you connecting it to household outlet that supplies power? Do you have a commercially-built adapter, or a homemade one? It is very easy to build an improper 15-to-30amp adapter, and this is commonly seen.

How do you know that all receptacles in the TM are wired properly? Do you measure the voltage at these receptacles? From hot (narrow slot) to ground (round slot)? If so, did you do this when the TM was plugged into the improperly grounded receptacle, or the properly grounded one?.

You should go to a hardware store or big box store and get a 3-light tester similar to this one. Maybe $5.
http://www.trailmanorowners.com/foru...&pictureid=452
Unplug the TM from the first outlet and plug in the tester. My guess is that you will find a fault there. Now plug the tester into the properly-grounded outlet. My guess is that all will test good.

Let us know. By the way, what year is your sister's 2619?

Bill
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GolfingDebby · 06-15-2016, 08:27 PM

The TM is a 2009. About the improperly grounded receptical...it is a 3 prong garage outlet and I was using the 3 light tester you recommend...it read "open ground" only. Tester did not indicate "hot/grd reverse" or "hot/neu reverse". I am not using a 3 to 2 adapter. Using the tester on the properly wired 3-prong outlet in the house the tester read "correct". I am using a commercially built adapter with a heavy duty 3-wire yellow extension cord.

I did not measure the voltage in the TM outlets. Just used the 3-prong tester on them. I tested them when it was plugged into the ungrounded outlet.

Can an ungrounded outlet by itself cause the "hot skin"?

Thanks for all your help over the last 3 years. We've used many of your suggestions.

Doug

**Bill** · 06-16-2016, 07:04 AM

Doug -

Good info - thanks for taking the time to write it up. It eliminates a lot of possibilities.

A quick question. When the TM is plugged into the "bad" outlet, and you use a meter to measure 118VAC on the hot skin, presumably you are measuring from the skin of the trailer to a known good ground somewhere. Tell me about this ground - what/where is it?

It is important to note that in the absence of a ground, a 3-light tester cannot indicate hot-neutral reverse. Only one light will light, and it will light whether hot and neutral are correctly connected, or reversed. So I still think the bad outlet is not only missing the ground, but has a hot-neutral reverse.

Since you have a meter, you can confirm or deny this by poking one probe into the narrow slot in the bad outlet, and connecting the other probe to a good earth ground such as the one I asked about above. It should indicate 120 VAC, give or take a very few volts. Then move the first probe to the wide slot in the outlet, and measure the voltage to ground again. It should read zero, give or take a very few volts.

No, an ungrounded outlet alone cannot produce a hot skin. The presence of a hot skin means that there is a fault somewhere, because the hot side of the supply should NEVER, under any circumstances, be connected to the trailer skin, even a little bit. The trailer skin is grounded, so if the hot side of the supply is somehow connected to the trailer skin, it should instantly pop a breaker. However, if the skin is not grounded because the ground wire in the outlet is disconnected, the breaker will not pop and you are left with a hot skin. In other words, the fact that the ground is missing will not cause a hot skin, but it will fail to protect you when a hot skin situation arises. So you have a fault somewhere.

Come back with your results.

Bill

Padgett · 06-16-2016, 08:51 AM

Guess my first thought was that voltage does not necessarily mean current, might just be inductive. Many meters today have very high impedances. A better test would be to connect a resistive load like a light bulb to ground and measure across that.

GolfingDebby · 06-16-2016, 03:22 PM

Bill,
The ground used when measuring the "hot skin" was a metal fence post and then on a second check the probe was stuck in the earth.
On testing the ungrounded outlet - Narrow slot grounded to earth = 120VAC. Wide slot to earth = 2VAC. Receptacles in TM registered the same as above when plugged into the "ungrounded" outlet.
Thanks, Doug

**Bill** · 06-17-2016, 06:33 AM

Next step - turn off the circuit breaker that controls the TM's water heater. Does that make the hot skin go away?

Bill

GolfingDebby · 06-18-2016, 12:28 PM

Bill,

I turned off the hot water heater breaker, no change...still hot skin. Systematically turned off each breaker...no change, still hot.

Thanks, Doug

**Bill** · 06-19-2016, 07:45 AM

Curiouser and curiouser.

In your previous post, you say that you switched off all the circuit breakers, including the main 30 amp breaker, and you still have hot skin?

How did you discover the hot skin? Did someone get a tingle when touching the doorknob, for instance?

If there is no tingle, I'm going back to Padgett's post #5. Can you arrange to connect an electrical device such as a table lamp between hot skin and ground? Does the lamp light, even dimly? Does the hot skin go away?

Bill

BrucePerens · 06-19-2016, 05:00 PM

Sounds like the shore power outlet or the trailers shore power cord may be wired hot to ground, not ground-open. If hot-to-ground shore power is the case, nothing about the trailer will fix it. Check the outlet with a meter between the ground pin and an independent ground like a ground rod (not otherwise connected) or metal water pipe going into the ground.

Next do the same thing where the shore power wire reaches the converter. If it's hot to ground there, disconnect it from the converter and check it again.