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Julison · 08-04-2009, 09:32 PM

Hi,

Just finished a 14 day summer vacation in our 69 Caravel.
Great time, even in the near continuous rain.

However I'm quite worried about that my 6 year old daughter complained that she felt tingling when she touched the door. We've never sensed this before. I've read many of the posts about trouble shooting but have a related question that I couldn't see in the posts I've read.

There is an outside light just right of the door. It has always only worked intermittently, so I thought I would begin my short investigation there. When I removed the light housing I noted there was an old decaying gasket between the light housing and the door skin. THere was only a black wire attached to the light - no neutral or ground. There was a screw on the back of the housing without any wire attached. I probed around behind the skin amongst the insulation and found a white neutral not attached to anything. I attached it to the screw on the back of the light housing and reassembled ...sealing the assembly with vulkem.

My daughter said she didn't feel the tingling anymore...but I'm not convinced that I've fixed anything as the light still works only intermittently.

Does anyone know if the white wire should have been attached to the screw on the back of the light housing? If the original gasket failed...would that have made the skin the neutral as the metal light housing would now be in contact with the skin.

Any help would be appreciate it.

P.S: When she said she felt tingling, I disconnected the AC..but she still claimed to feel it.

thanks

Julison

Julison · 08-05-2009, 04:57 AM

HI,

So I went out first thing this morning with a circuit tester and plugged the AS into the home GFI outlet. No breaker thrown. Checked the polarity light and it was off (the shore power light was illuminated though). Placed the red probe of my circuit tester in the power of the wall outlet and the black into the return of the outlet - prober light is on. I then left the black in and placed the red in the third prong of the outlet and the light did not come on...good.

However, if I take the Red probe and place it in the power prong and then take the black and connect it to the screw holding the faceplate of the outlet...the light goes on. IS THIS CORRECT?

I did a hot skin test by placing the black prong in the known good ground from an extension cord plugged into my homes outdoor GFI. I then placed the red probe against skin of the trailer and then the frame of the trailer...no light came on. I take this to be a sign that the frame and the skin are not conducting.

Does all the above sound normal for a properly functioning electrical system? Perhaps my daughter really was feeling static (although it was raining at the time).

thanks in advance all for any help here.

Julison

DEITZ645 · 08-05-2009, 05:32 AM

Julison,
I had a similar experience in our '06. I got a tingling sensation when I was bare footed, stading in damp grass, and went to open the screen door. Of course I had to get my wife to test it too

and she got the same tingling sensation. What I tracked it down to was the 15 amp extension cord was not fully plugged in and grounded in the garage outlet. So now I leave one of these testers plugged into the 110 outlet right inside the door. That way I can tell at a glance that I have shore power and the trailer is properly grounded.

Electrical Receptacle Tester with GFCI Diagnosis

DesertStream · 08-05-2009, 07:05 AM

Julison,

I had a similar problem on our 1966 Tradewind. It was however causing the GFI on the shore power outlet to open. I tracked it down to circuit on the curb side of the trailer. Ultimately I replaced the outlets on this circuit and it fixed the problem. My theory was that forty some odd years of dust accumulation was causing a ground fault in one or more of the outlets. Since your outside light is 12 volt I don't think that it had anything to do with the problem. It is more than likely a faulty ground connection to your chassis.

modarch · 08-05-2009, 07:23 AM

I had a similar problem on my '67 Caravel. The copper grounding wire that came out of the fuse box and went to the frame- the bolt was totally rusted away. A new bolt did the trick...

Lumatic · 08-05-2009, 07:24 AM

Quote:

Originally Posted by Julison

Hi,

There is an outside light just right of the door. It has always only worked intermittently, so I thought I would begin my short investigation there. When I removed the light housing I noted there was an old decaying gasket between the light housing and the door skin. THere was only a black wire attached to the light - no neutral or ground. There was a screw on the back of the housing without any wire attached. I probed around behind the skin amongst the insulation and found a white neutral not attached to anything. I attached it to the screw on the back of the light housing and reassembled ...sealing the assembly with vulkem.

Does anyone know if the white wire should have been attached to the screw on the back of the light housing? If the original gasket failed...would that have made the skin the neutral as the metal light housing would now be in contact with the skin.

Julison

You would not feel 12v. In fact the running lights are grounded to the skin anyway. I'm guessing it's your 120 system. It may save a lot of guesswork if you get tester you plug into a 120 outlet. This will check polarity, grounds etc. There are 2 types available the 2nd type does everything the 1st does but also checks GFI. The cost the same. a couple of bucks. I learned the hard way to always use one of these gizmos to check polarity of campsite power.

The white wire should be nuetral.

HowieE · 08-05-2009, 08:03 AM

Get a digital voltmeter and test the trailer skin to a known good ground, directly back to the house. Let us know what the voltage comes out to be.

Sounds like you have a 120 volt leak to the skin. My question is why didn't the house GFI blow as soon a she touched the trailer.

As noted above check the trailer electrical panel and trailer frame ground connections. If these prove to be loose or dirty and after you fix them let us know if the GFI pops because that will indicate a short to the skin is there.

Julison · 08-05-2009, 09:05 AM

Thanks all,

120v must be the source...but please see my 2nd post on this item as I've done some more checking and had some observations that lead me to think the problem may be intermittent or non existent.

Has anyone ever considered doing the hot shell test by running a metal bar into the ground and then using the meter to check for current flow from the shell to the ground? I thought if my problem is intermittent I could do this test at each campsite before I let anyone in the trailer. This would be a sanity check that would eliminate any questions about the parks electrical ground and any short that may be coming from my trailer.

thanks again...the forums are great for gathering ideas.

Julison

rangebowdrie · 08-05-2009, 09:48 AM

The effectiveness of a ground rod is totally dependant on the conductivity of the soil/earth.
A seperate wire, from the trailer shell/frame, going to a known good ground; cold water pipe, ground buss in breaker box, etc.
This wire can then be tested for any currant flow.
Many times a leaking system will have much less than 120V, allowing a "tingle", but not enough for a "shock".
The plug-in testers are a good thing to use, I also leave one plugged-in to an outlet.

HowieE · 08-05-2009, 10:01 AM

You all ready have a "ground rod". It is supplied by the utility company. The trailer shell is grounded via the ground leg of the 3 wire connector. That is why I suggested you connect to a known good ground in the house and test the shell. If you see voltage during this test there is an open in the trailer ground circuit. Check the frame and panel connections.

Julison · 08-05-2009, 10:12 AM

Thanks,

My plan for the good grounding rod was not for when I plug in at home (where I know I have a known good ground) but to be used at campsites where the quality of the 3 grounding wire may be unknown.

I think what I am hearing is that the best defence against this is to have a plugin tester that is permanently plugged into a recepticle of the trailer.

thanks again everyone.

Julison

HowieE · 08-05-2009, 11:37 AM

If you question the camp ground ground do it at the campground post. If you wait to get inside the trailer you might be dead before you get to the meter.

I have seen 70 volts on a trailer. The camp ground knew they had a problem but it only happened when another camper plugged into the other side of the run to the post we were on. Well someone came in and they rented the site and we got a good shock when we returned. But they said they were going to have it fixed someday.

Julison · 08-07-2009, 01:29 PM

Ok,

So I bought a multimeter and set to investigate if there truly is a short to the trailer skin.

I used an extension cord to my house as the "good ground" in all these tests.
My breaker box in teh trailer has one 30 A and two 20A breakers.
When hooked to 120 and I have all the breakers off - I read near zero volts (skin to ground).
When I turn on the 30A breaker I read 4V.
When I then add the first 20A breaker I go to 8V.
When I add the 2nd 20A breaker the multimeter reads 17 volts.
I could hear a distinct hum from the breaker box when I opened the 2nd 20A breaker (this circuit) serves the interior lights.

So, what should I make of this data...are all circuits shorting to the outside of the trailer (skin)?

When I plugged in a 120 circuit tester into all the interior receptacles, there was no error noted. When I plugged in the tester into the outside 120v receptacle it said there was an open ground...what does that mean? I opened that receptacle and all wiring looked okay...old and somewhat rusty....but the wires connections all looked solid.

Finally, I pulled the panel off the breaker box and took some pictures fo rreference.
I note that one circuit wire was cut off ... I have no idea of what this wired served as I have lights, 120V power to receptacles and fridge.

Any guidance on what my next step should be?

nate3172 · 08-07-2009, 02:50 PM

Does your air conditioner work?

Julison · 08-07-2009, 03:16 PM

Quote:

Originally Posted by nate3172

Does your air conditioner work?

Unfortunately, there is no A/C...I'm not sure it ever came with one..but that is a possibility for the errant wire.

thanks

Minno · 08-07-2009, 03:29 PM

That extra wire probably goes to where the a/c would be installed up on the roof.

The open ground on the outside outlet is worrysome. Do you have any idea where the wiring comes from? Is there a GFCI outlet, perhaps in the bathroom, that feeds the outside outlet? Anyway, the open ground might be on the other end of the wire - for example on the next outlet upstream from the outside one, or in the juction box of the next upstream outlet. Let's hope it on the other end of the wire, and not the wire itself being broken somewhere inside the wall...

Chris

klattu · 08-07-2009, 04:13 PM

Yes,
As others say, the ground is not complete somewhere.
Check all the way back to house.
Extension cords are most common problem.

And yes you can feel 12 volts!!!!
Ask any mariner that works on boats around salt water.
It feels more as acid eating at you than a shock.

Julison · 08-07-2009, 05:00 PM

Quote:

Originally Posted by klattu

Yes,
As others say, the ground is not complete somewhere.
Check all the way back to house.
Extension cords are most common problem.

Just checked the ground of the extension cord....all good thus far.

I'll keeping looking.

ANy idea on why the volts to ground increases for each breaker I open?
Does this mean that each of the 3 circuits has its own short...or does it maybe provide a clue that the short is back at some common junction - say the univolt?

nate3172 · 08-07-2009, 05:56 PM

Consider this possibility. If all your internal outlets test fine but the one on the outside does not than meybe the sockets inside that outlet are corroded enough that the tester does not make good contact with the ground socket. It is an outside plug that is essentially sealed with a cover but that does not necessarily mean that it has not been exposed and sealed well enough. Maybe the outlet itself is bad. Also, as a parent myself I have a tendancy to take what my kids say for there word, but a childs imagination can sometimes play a factor. Another possibility is that the shore power you were plugged into while your daughter experienced this had the problem and not your trailer. I highly doubt the univolt would be creating the issue because it is screwed down to a wood floor isn't it? Well, at least mine is so it is insulated from the exterior shell.

nate3172 · 08-07-2009, 06:06 PM

Oh yeah, klattu, she isn't standing in salt water and it's not the voltage they feel it's the amperage. Not trying to be smug or anything but a leaking d/c system will not just trickle low current through the shell if the positive wire is touching it. It would be a direct short and blow a fuse or melt the wire.