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weiss1957 · 12-26-2008, 06:43 PM

Last night when I went to show off our new 1970 Airstream Caravel to some family members that were over for Christmas I had an unexpected surprise. I walked out barefoot on wet concrete and when I went to open the door I got shocked. I unplugged the shore power and then it was no problem. Today I tried to find the problem by using a circuit tester and found that I had an open ground on the AC plug I was using. When I tried another GFCI circuit it tripped.

I can still plug the AS into a grounded kitchen outlet (non GFCI) and it works fine, but I am reading about 2 VAC from the skin of the trailer to earth (ground).

Any ideas of where to start troubleshooting? I can read a meter and turn a wrench, but I am a bit puzzled. Any help would be appreciated.

Thanks,

Mike

Inland RV Center, In · 12-26-2008, 08:13 PM

Quote:

Originally Posted by weiss1957

Last night when I went to show off our new 1970 Airstream Caravel to some family members that were over for Christmas I had an unexpected surprise. I walked out barefoot on wet concrete and when I went to open the door I got shocked. I unplugged the shore power and then it was no problem. Today I tried to find the problem by using a circuit tester and found that I had an open ground on the AC plug I was using. When I tried another GFCI circuit it tripped.

I can still plug the AS into a grounded kitchen outlet (non GFCI) and it works fine, but I am reading about 2 VAC from the skin of the trailer to earth (ground).

Any ideas of where to start troubleshooting? I can read a meter and turn a wrench, but I am a bit puzzled. Any help would be appreciated.

Thanks,

Mike

Go to Home Depot and pickup a "polarity tester."

The source of power to your trailer is incorrectly polarized, or the trailer is mis-wired.

Start your tests at the source of power.

Andy

HeadnOut · 12-26-2008, 08:18 PM

Not sure I ca help, but I have a few Questions.
...for your shore power, what kind of power cord ar you using?
...was the cord laying in the water and could it have a short or a bad spot on the cord?
...is your electrical ground wire connected to the trailer properly?
just a few thoughts to start with.
Headn'Out

vikx · 12-26-2008, 11:43 PM

I agree with Head'nOut, grounds are often the cause of GFI problems and "shocks". Check your 110 electrical box and the chassis ground. The other thought I had was a frayed shore power cord or has it been "yanked" a good one by a PO? Check the junction box and connections there. Let us know...VK

Ifihadtime · 12-27-2008, 12:32 AM

Along with everything else said, turn off all the breakers in the trailer and check for the leak. If you don't find one flip on one breaker at a time to see which circuit has the leak. Hope this helps, let us know what you find.

vinstream · 12-27-2008, 12:47 AM

If your get shocked... then I would think that the wires coatings somewhere have rubbed off and is connected to the aluminum frame somewhere... water could also be making the connection. I agree with Andy and start testing all the different areas and find out where your system has gone wrong!

Vin...

HowieE · 12-27-2008, 08:58 AM

If you do not find the problem to be polarity at the source remove the electrical power panel cover and check polarity of the shore cord, with all breakers off, as it enters the panel. If these check out OK connect your voltmeter between the trailer and a GOOD GROUND, back at the house, and start turning on each breaker one at a time to isolate which circuit is giving the problem. Once the circuit is located remove items that may be plugged int that circuit one at a time. Don't forget the refrigerator, converter, and the door bell.

Keep this in mind. Even if you find and remove the voltage problem you may still have a problem when plugging into a GFI. This is because GFIs sense ground current and some electrical items, those that have a transformer on the input, may have a capacitor across the line before the transformer. The charging current of the capacitor is enough to trip a GFI. The only way around this is to get rid of the GFI or the electrical item. This tripping does not pose a hazard just a nuisence.

weiss1957 · 12-27-2008, 09:07 AM

Some good ideas. Here is my plan for today. Properly ground the GFCI outlet that has a floating ground, then try to find if I have a 120 VAC short to the trailer somewhere.

I was plugged into my garage (the GFCI outlet with the floating ground) when I got shocked. After that I tried to plug into a properly grounded GFCI (same garage different circuit) and it tripped the GFCI. I finally went into the house and plugged into a kitchen (non GFCI) properly grounded circuit. I didn't get shocked in this configuration, but by then it had quit raining and Darwin had taught me that I ought to be wearing shoes...

Shore power was connected with a brand new 15A extension cord adapted to my brand new 30A/15A pigtail from Campingworld. I will say that the old (1970's) 30A cord looks pretty old, but I am sure it was up out of the water when I got shocked. I may replace it anyway as it looks like something that might try to kill you.

So... where do I find the breakers in my trailer ( I just brought this 1970 Caravel home) I looked all around yesterday and didn't see any.

Thanks,

Mike

Jim Clark · 12-27-2008, 09:14 AM

I keep a polarity checker plugged into the receptacle by my stove, I used a marker to color it from yellow to silver to match the aluminum. Now no matter where I camp when I plug the unit in I know the status of my power. Cheap safety check.

weiss1957 · 12-27-2008, 09:31 AM

Does anyone know where the electrical power box is on a 1970 Caravel? I thought I saw one somewhere in that thing, but looked all over yesterday and didn't find it.

As for the polarity tester... I am sold. I will henceforth wear one around my neck on a string and test all circuits high and low. I will keep one in my trailer, my bathroom, and my shaving kit for when I go on travel to an unknown hotel...

Thanks,

Mike

goransons · 12-27-2008, 10:55 AM

Our 69 breaker box is directly over the water heater in a cabinet in the bathroom. Not sure with yours being shorter and one year newer if its the same but worth checking.

weiss1957 · 12-27-2008, 07:15 PM

I found the breaker box located in the tall closet next to the head. It was behind a thin wooden wall. There was a hole cut so you could switch the breakers, but I needed the cover off.

I spent all day rewiring my garage to make sure that I had that freshly grounded feeling, installed an 8 foot ground rod and tied my GFCI's to that. While I was at it I added a receptacle nearer the trailer and one on the outside wall as well.

With all that fine electrical work out of the way I switched off all my AC breakers in the AS and plugged the trailer in. GFCI tripped in about one second. Hmmm... perhaps the old 30A cord is frayed or is grounding prior to getting to the breaker box. I guess tomorrow I will try some continuity testing to see if that solves the mystery.

I am attaching a pic of my wiring diagram in case anyone wants to ponder it a bit. Any other suggestions/great ideas would be welcomed.

Thanks,

Mike

HowieE · 12-27-2008, 08:47 PM

The next thing I would do is remove both legs of the shore line from the terminals in the box and float them in open air. Then plug the shore line in. If it blows then the cord has water in it.

letsgo · 12-27-2008, 09:19 PM

First a FLOATING GROUND IS THE POTENTIAL DIFFERENCE BETWEEN 2 GROUND POINTS this is due to poor grounding design along with improper electrical phasing.

Next a correctly grounded trailer is designed to protect you from INTERNAL GROUNDS WITHIN THE TRAILER ( electrical wiring or electrical devices ) BUT and I say BUT again no amount of protection built into the trailer is going to protect anyone standing in water and touching an electrical apparatus of metal.

third you have a high resistance ground not a short circuit. The high resistance ground can be sourced from 120vac appliances or 12vdc , 12vac equipement. be aware that to obtain 12 volts you can use auto transformers or wire wound resistors that have voltage taps, any problems with these 2 items can also creat voltage leaks, and open neutrals can create wierd voltages and back feeds.

safe rving

LHall · 12-27-2008, 09:32 PM

We had the same problem with our trailer when we first purchased it. Turned out that the shore power cable was riddled with small cracks and dry rot. The problem was completely resolved when we changed the shore power cord. Additionally, since this was occurring, it ended up frying the AC unit. I would start with the cord. Quick continuity checks on each power leg of the cord to ground should help identify this problem.

vikx · 12-27-2008, 10:30 PM

Totally agree with a new cord-could have gotten way hot or be corroded...especially if it trips the GFI when all the breakers are off. Another GFI culprit can be the refrigerator. Try unplugging it. VK

Janets Husband · 12-28-2008, 09:37 AM

OK
First thing, Disconnect the triler from shore power!
This is a real world example of why you don't ground the neutral leg in a trailer.
If for some reason the shore power should have the wrong polarity, you will energize the the trailer shell.

Now as to your troubles, if this problem has just started I would look at any recent repairs. Check to make sure that any recent repairs did not cause a mis-wire, or a screw driven through a wire somewhere. Look at ANY repair.
Check your 120Vac supply outlet for correct polarity.
Check your shore power cable to the trailer with an Ohmmeter. Check the Hot, Neutral and Ground leads to the trailer shell. If any lead but the Ground Lead has a connection to the shell you have a problem.

The easiest way to isolate a problem in the Hot Lead to the shell is to turn off the Breakers one at a time while reading the power connection with an ohmmeter. This will give you a direction to look.
The problem should be in the Hot Lead unless the shore power or your trailer shore power cord is mis-wired and your neutral is grounded in the trailer.
If you have a grounded neutral problem you will have to open the trailer service box and the remove the neutral leads one at a time until you located the offending wire with the Ohmmeter.

Once you have located the bad wire, Hot or Neutral, then you will have to look at where it is connected and disconnect whatever is connected to it. AC unit, refrigerator, toaster...
Chances are some appliance has a problem and will need to be corrected. If it is a wire with the insulation rubbed through, it will be a real tough repair.

I hope this will give you some direction in troubleshooting your problem.
Remember to Work with the Power Disconnected at all times.

HowieE · 12-28-2008, 11:31 AM

Mike

If you end up replacing the shore cord and it looks like a problem getting it through the trailer body consider installing a splice box just where the cord enters the trailer and splice in the new cord there.

Cut the cord just inside the body and test it to make sure there is not a problem in the body from there to the panel. If OK use that section of the cord and splice on the new one.

Short of someone driving a screw through the cord inside the body that section of the cord should not fail.

When I replaced a section of the floor I found 6 feet of shore cord lying in the belly pan. Pulled it out and now have an additional 6 feet of shore line.

Inland RV Center, In · 12-28-2008, 11:44 AM

When a city power cord goes bad, why replace it with the original 25 foot cable. Actually, it's less than that since 5 feet or so of it is buried within the trailer.

We have the Canadian power cord, which is exactly the same, except it's 36 feet long.

Makes a huge difference in many hookups.

Andy

weiss1957 · 12-28-2008, 04:50 PM

So far I have found that there is no problem with the shore power cord. I have a neutral going to hard ground on one circuit. It appears to be the circuit that provides power to just about all of the AC outlets in the trailer. I have been disconnecting them, but so far I don't have the source of the ground. I will update you when I find it or burn the trailer to the ground trying to find it.

Thanks,

Mike