Please help identify this wire

[chingon]

first,
thanks for all the wisdom i've been soaking in since buying my first AS...

at initial hook up to shore power i experienced the fairly typical GFCI trip, with all circuits off, and after testing all the outlets i poked open the service panel and found a stranded white wire connected to the ground bus - i thought i had found my problem. chasing the wire i found it disappears between inner and outer skin on the streetside rear. any ideas what this might be? attached is an image of the wire as found in the service panel. thanks in advance

[Mexray]

Will have to check my wiring diagrams to see if that wire is shown...

As it's hooked to the grounded buss bar, I would think the wire goes to the chassis ground somewhere, frame, skin reinforcement, etc...

[NevadaGeo]

That white wire is probably hooked to ground somewhere, on the frame. What puzzles me is looks like a small black wire behind it hooked to the ground buss, and also a small black wire hooked to the top white neutral buss. White should be used for neutral or ground, black should be used for the hot, energized side on an alternating current system. Different in the DC side. Oh, is the ground (Black) on the DC side hooked into the neutral and ground on the AC side? Now it could get interesting.

[chingon]

thanks for lookin' gang. i thought it might be a frame ground as well, but the absence of it being re-coded with green tape gives me reason for pause. i haven't looked at the DC system much yet, aside from opening the cover on my converter and realizing i have a bunch to learn. can't say if the DC ground is tied to the AC ground and neutral, it seems as though i should hope it is not. i could do without things getting much more interesting.

[TG Twinkie]

What did you use to do the testing?
Do you have a 30 amp service in your trailer or is it 20amp.
If you know how to use a Volt Ohm meter you can check the white wire to see if it infact is connected to the frame of the trailer.
If you don't know how to use the meter, we can give you instructions.
Stranded wires are usually associated with the DC side in a travel trailer.
Is it a single wire or does it meet up with a black before it leaves the panel?
I'm assuming the breaker that is tripping is in the house panel, not in the trailer. Is this correct?
Does the GFI breaker trip with all of the breakers in the trailer turned off?
Is the ubilical cord hard wired into the trailer or does it plug into the outside of the trailer? If it plugs in to the outside then disconnect it from the trailer and see if the GFI will hold with it just plugged into the house. If the UCord is old and dried out, that could be the problem.
Try this; disconnect the white stranded wire from the ground buss. Then reconnect the power and see if the GFI trips.
If that is a black wire connected to the neutral buss; disconnect it as well and retest..
The neutral should not be grounded in the trailer.

[68 TWind]

Check the outside 120v outlet. My 68 kept kicking the GFI outlet I had it plugged into (just running a drop light to keep my water pump warm). Started kicking it for no apparent reason. After a lot of head scratching and advice from a fellow Airstreamer, I pulled the outside outlet. It was wet and corroded. I replaced the outlet and install a new style outside cover and gasket and no more tripped GFI.

[chingon]

tg - thanks for your response. testing was done with a 3 prong plug in affair, i have a multimeter, but only have a barely working understanding of how it might diagnose problems, so any instruction would be much appreciated.

original service was 30 amp, but PO removed the 30 amp breaker and hardwired a 10/3 20 amp cord to the service panel. i still have the 30 amp breaker, but its neither HOM or CQ, maybe time to replace the whole panel?

it is stranded, 10ga perhaps, and does not meet with any other wires before it disappears into the inner skin - could this be an connection to my univolt?

yes, GFCI tripping at the house with all breakers off. the cord has been well used but not too abused . i've disconnected the wire from the ground bus, but before pluggin back in i thought i'd see what the forum had to say - as best i can tell, no hot is connected to the neutral bus.

68 twing - i didn't test the outlet outside, will be my first order of business after work - thanks

[TG Twinkie]

Can you post a photo of the front of your meter? I will help you learn how to use it.
So there is no outlet on the outside of the trailer that you plug your UCord (umbilical cord) in to?
When you say it's hard wired. Is that to an outlet on the side of the trailer or does the UCord come all the way into the panel?
If it comes all the way into the panel: Make sure the power is off then disconnect it from the top of the circuit breaker (where the red wire is connected). Also disconnect the white wire that is part of the UCord. Screw a wire nut on the end of both wires or tape them off so they aren't touching anything. Then plug the UCord back in at the house or turn the circuit breaker on and see if it trips the breaker.
If it trips; it means that the UCord has deteriorated enough that the insulation has broken down, causing the GFI to trip. You will need to replace it. If the breaker does not trip, we will move on to the next step in troubleshooting the problem.

[NevadaGeo]

What I understand, GFCI like infinite resistance, no conductance between the hot wires and the ground. If the ohm meter reads anything but 0 between them at the GFCI, it don't like it.

[NevadaGeo]

Originally Posted by NevadaGeo

What I understand, GFCI like infinite resistance, no conductance between the hot wires and the ground. If the ohm meter reads anything but 0 between them at the GFCI, it don't like it.

oops, read infinity there instead of 0. Details, details.

[TG Twinkie]

I have serious doubt that you could read the low amount of conductivity that would cause the GFI to trip with a meter. At the most the meter might have a 9 volt battery to provide the Ohm meter with the power it needs to read different resistance. In order to check for things like insulation breakdown you would need a megohm meter or similar device, which will generate a significantly higher voltage to detect insulation breakdown or deterioration.

[chingon]

thanks again for responses gang...

tg - yes the u-cord is wired directly to the panel, i'll isolate the cord and report back.

i did however just notice something in the panel that you must have seen in the posted photo, there is a stranded black wire attached to the neutral bus. disconnecting it, as well as the larger stranded white wire yielded the same results - tripped GFCI.

my plan is replace the cord even if it doesn't turn out to be bad - i want to return to 30 amp service. i would, however like to isolate the problem before the switch. i would also like to replace the breakers in the AS for a fresh start, but as they are neither HOM or CQ i am at a loss. thanks again!

[chingon]

round 2:

if it changes your advice i will also note that the u-cord connects from the bottom, you can see the larger 10 ga wire as it enters the panel and is dressed in a somewhat messy fashion. the red wire at the top is a bond or jumper of some sort - i always imagined it was bonding the main breaker to the rest of the branch breakers. thanks

[TG Twinkie]

At first glance I thought the breaker on the right was the AC (if there is one).
So the UCord is terminated to the bottom of the right hand breaker? If so that makes the breaker the MAIN.
What is the large black wire that looks like it connects to the top of the left hand breaker?
This would not change the method that I would use to troubleshoot the problem.
Turn the power off.
As before, disconnect the UCord wires and tape off the ends.
Turn the power on and see if the GFI holds.
If the breaker holds then trips after you reconnect the UCord we will move on to the next step.
Do your best to identify where the large black (stranded ??) wire goes. Something is not right there.
Be sure to turn the power off when working in the panel.

[chingon]

tg- thanks for stickin with me on this one, the u cord terminates under the tandem 20 amp breaker and is connected to one of these breakers, making it the main which is admittedly a little odd as i understand it. this is the black 10 ga black wire connected to the left breaker. i do have an AC, so perhaps that is the 15 amp breaker on panel right.

i'll isolate and test the cord tomorrow and report back...

there is a small stranded black (looks smaller than 14 ga) wire attached to the neutral bus, but as i glean from your responses, black on a DC system is the ground. why would the DC system even run to the AC panel - should it not interface at my "constavolt" converter?

i'll also try to take a better photo tomorrow, where shadow doesn't block some of the view.

[TG Twinkie]

Black on DC is normally the +12 volts. White is -ground or common. This applies to trailers.
Now in your car or truck Red is +12 volts and Black is -ground or common.
More photos will be good. Take one of the converter as well.
Can you tell me where the large Black and large White wires go? It looks to me like the large black wire terminates on the top of the left hand circuit breaker where one end of the red wire is terminated.
Are these wires (large black and white) stranded or solid?
What size is the breaker on the right?
Look on the outside of your trailer and see if you can find a receptacle that was used for the UCord in the past.
You say you have the 30 amp breaker that the PO removed?
You can copy and paste my questions into your next post and then go in and answer each question. It will help keep things straight.

[TG Twinkie]

On the right side of the panel there are three cables leaving the panel.
Can you identify what they are?
Is one of them the UCord?
It looks like there is a Black and White wire leaving the top connector just below the cable. Is this true?
Do you know where they go?
Is there another cable going out the back of the panel just below the 2 circuit breaker on the left?
Can you get on your computer while you are in the trailer. If so we could set up a time and communicate directly in real time.

[TG Twinkie]

Chingon: I just realized I have been using the wrong terminology when talking about the 120 volt AC power cord going to your trailer. This is called the shore power cord not the UCord. I've been working with someone else on their 12volt system. The UCord is the one that goes to the tow vehicle. I just got locked into the "UCord" in my brain. So from now on we will refer to it as the Shore Power Cord.

[garry]

From what I see the shore power comes in on the 10 gage stranded (could be solid) white, black, green wire . The white & black off to the left and green to the ground buss. The hot (black) is jumped to both circuit breakers by the red wire.

That is the 1st problem you are now protected only by the CG 30 amp breaker. Most load centers I have seen like this the shore power(black wire) would go to the breaker on the right (a 30 amp) and out of that breaker to the input power lug on the top left. “Doesn’t have to” but provides you the protection of a 30 amp breaker in the coach.

As it is now if the CG breaker is defective and fails to trip or is wired wrong you could pull up to 55 amps on your shore power cord.

The current set up looks like 2 @ 20 amp breakers on the left and a 15 on the right. I would guess one 20 for the AC one for the wall outlets and the 15 to the HW heater.
The white wire going into the ground lug (pointed out) looks like a single wire coming through the bottom of the box from where? And a single black wire comes in from the top right and goes where???

Main cause for GFCI tripping is the outside 120V outlet also a frayed shore power cord but it could be a fault in any down stream outlets. They usually protect the bath, kitchen and outside outlets.

[TG Twinkie]

I think Garry is right. The large Black, White and Green wires look like they could be the shore power cord, now that I look at it again. And the large black wire must terminate along with the red wire on the top left buss lug.
I was able to enlarge the photo and now can see that the shorepower cord (?) comes in the bottom of the panel.
The white wire on the right that goes thru the bottom of the panel is probably going to the skin of the trailer somewhere.
By the looks of the romex covering all of the wiring going out the right side of the panel is original.
I agree that one 20 amp circuit would go to the outlets and another to the AC. I don't believe the water heater had electric backup in those days, mine didn't.
The 15 amp breaker probably supplies the power to the refer. Which would normally use just over 150 watts when on electric.
I would reinstall the 30 amp breaker between the 15 and the 20 then connect the shore power black wire to the bottom of the 30 amp breaker, leaving the red jumper in place to provide power to the outside buss. This would be the main breaker.
Still am confused about the black wire that goes out the top right corner of the panel just below the romex.