Electrical short

mikemakay · 06-13-2020, 08:05 PM

I have a new to me 2011 Journey Express 34y. I hooked it up to shore power and was loading one of the storage compartments in prep for a short road trip. As I was getting up from kneeling on the ground my forearm touched the top or the storage door and I felt a "tingle". When I touch it with my hand I don't feel anything but when I touch it with my forearm or my upper arm I feel the voltage. I grabbed my multimeter and checked it and it read 19.2 ac volts.
My question is where do I start checking for a short in the system?
Thank all you guru's in advance for any help.
Mike

Morich · 06-14-2020, 09:03 AM

Always an interesting topic and you look like you have some tools, but first a word of caution as it can go from funny to really bad if we are not careful. Take care as moving things around or a simple door slam can move things to make better contact and that 20 volts can go to 120 really quick!
But assuming you knew that , I would go with first trying to find which circuit has the fault. Since you have found it is the AC system, that cuts the chase a bunch, so how much do you know about your RV electrical panels like breaker locations?
My thinking is that you will be reasonably safe to go to each panel that has AC breakers or fuses and pull or flip each breaker/fuse as I watch your meter to see when it shows the power gone.
The thought is that one of the breakers will turn off the power going to the circuit with the fault. It may not be the internal RV wiring but something like an electrical cord or item like VCR, lamp , Frig, TV may also be the problem.
So there may be value in first checking the easier things, but what is easier to check will depend on what you are speaking of. Going around to unplug all the portable electrical items like lamps sounds easy enough but getting behind a flat screen Tv screwed to the wall may not!
So a combo may work best, unplug the easy stuff to know for sure it's not something like a stereo receiver with an internal defect but then going for trying to isolate it with the fuses or breakers may get easier than taking the TV off the wall. Needs some on-scene thinking there.
So how can we best help? Do we need to try to locate drawings for where the panels are or do you know? If you can isolate it down to some specific circuit, we can then go to look for drawings and hope we can locate one that shows where that line of wiring goes as it is likely to have more than one item on the circuit. Some year, make and model we can get great info of that sort while others, we get very little.
But first step for me would be to try to isolate it down to some specific circuit that has the fault, whether it is an internal Rv wiring problem or something that we have plugged into that circuit. Big plus on that is leaving that circuit dead clears the hazard of touching the RV metal!
I'm open to doing a full blown bug hunt, so do some looking?

mikemakay · 06-14-2020, 09:12 AM

Morich, thank you for the insight. I will start doing some checking and keep you informed

Goodspike · 06-14-2020, 09:15 AM

What I would check first would be the shore power connection. The house outlet or whatever you're connected to. Make sure it is properly wired. It may not be a problem with the RV.

mikemakay · 06-14-2020, 09:19 AM

Thanks, I will check that also

Morich · 06-14-2020, 09:21 AM

Looks like a panel under the bed and I see 50 amp as well as smaller 15 and 20, so thought to mention that it is quite likely the smaller are fed through the larger, so I would suggest flipping the smaller to turn off a single branch circuit rather than the big which makes the power go away on the meter but only because we've killed the whole RV system. That doesn't tell you which circuit, only that somewhere in the whole RV.

EDIT:
Looking further, I find good info on wiring for your RV.
If you can access this drawing??? it has lots of the info for the next step:
http://www.winnebagoind.com/diagram/...ire_175978.pdf
Sheet one has the load center and where each breaker feeds and the path it takes to get there. If you can get to that drawing , you may be able to see it far better than what I could snip and copy in pictures.

mikemakay · 06-14-2020, 09:33 AM

copy that

powercat_ras · 06-14-2020, 10:21 AM

Measured 19.2 volts AC to where? The ground next to the RV ??? Please update.

You can google NO SHOCK ZONE and get good articles on RV electrical problems and the hazards associated with them. BE CAREFUL. If you can feel a tingle the situation could lead to an injury in particular to a child or person with underlying health condition.

**creativepart** · 06-14-2020, 10:49 AM

I'm centering on that voltage number. What puts out 19v AC on an RV?

Lot's of VDC chargers, devices that come close - such as the converter/charger, an inverter/charger, Solar Panels. And such.

Do you have an outside TV or soundbar that's AC powered?

Can you turn off anything and have the voltage disappear?

Goodspike · 06-14-2020, 10:55 AM

Quote:

Originally Posted by powercat_ras

Measured 19.2 volts AC to where? The ground next to the RV ??? Please update.

Quote:

Originally Posted by creativepart

I'm centering on that voltage number. What puts out 19v AC on an RV?

My guess would be the answer to powercat's question might answer creativepart's question. I'm suspecting it wasn't a great ground source and that's what gave the odd voltage.

Morich · 06-14-2020, 11:41 AM

Odd voltages come from high resistance shorts. That's part of what makes this a dangerous item.
There is currently a high resistance between the power source and the part being energized but that item may shift if we move something like slamming a door and make much better contact and that leaves less resistance and we can suddenly be hit with 120 instead of the funny tingle we got the first time.

Goodspike · 06-14-2020, 12:10 PM

Quote:

Originally Posted by Morich

Odd voltages come from high resistance shorts. That's part of what makes this a dangerous item.
There is currently a high resistance between the power source and the part being energized but that item may shift if we move something like slamming a door and make much better contact and that leaves less resistance and we can suddenly be hit with 120 instead of the funny tingle we got the first time.

That's sort of the other side--assuming a good ground, but I agree.

The other possibility if it gets worse is a fire eventually.

Morich · 06-14-2020, 12:30 PM

Whether the ground is a good low resistance ground or a high resistance one, it is the total resistance which controls how much current flows and that is what makes the difference in getting a tickle versus getting killed.
If the resistance from the hot wire to the Rv metal is 1 K and then contact between the person and ground is 20k , we get the same result (21k) as if the person was standing in water giving them a 1k resistance and the hot wire being a 20 k resistance. Current flow in a circuit is the same at any given voltage if the total resistance is the same.
Something farm kids learn when playing with the electric fence! When challenged, don't stand on the wet spot!

Goodspike · 06-14-2020, 12:52 PM

Quote:

Originally Posted by Morich

Whether the ground is a good low resistance ground or a high resistance one, it is the total resistance which controls how much current flows and that is what makes the difference in getting a tickle versus getting killed.

I would agree. My point has more to do with what caused the 19 volt (or whatever) reading. What I'm thinking specifically is the OP may have taken a multimeter and stuck the ground probe into the dirt or onto a rock. I've never tried that, but I'm thinking that probably wouldn't register 110 volts if you connected the positive directly to an extension cord.

Stated differently, the OP's issue might be more dangerous than what the reading indicated.

mikemakay · 06-14-2020, 01:31 PM

Thanks to all who offered suggestions for my problem. I decided to start with Goodspikes idea to check the shore power and found that I had an open ground. Once I repaired that I have no more tingle on my arm or any voltage reading off the storage door.

Thanks again to everyone

Goodspike · 06-14-2020, 01:48 PM

Quote:

Originally Posted by mikemakay

Thanks to all who offered suggestions for my problem. I decided to start with Goodspikes idea to check the shore power and found that I had an open ground. Once I repaired that I have no more tingle on my arm or any voltage reading off the storage door.

Thanks again to everyone

Glad I could help save you some time. I'm going to link this thread to the other thread about house connections. Your experience here would likely be identical to trying to connect to a dryer connection that only has three wires.

I'm just not sure that answers the question of why it was doing that. By "properly wired" I was thinking more a reversed connection. Something is possibly connected to ground (or frame) that shouldn't be. I'm gong to have to ponder whether additional testing is necessary.

Am I correct in assuming you're not plugged into a GFCI outlet? Perhaps installing one would be a good test.

Morich · 06-14-2020, 02:37 PM

Yes, a good ground will drop the voltage to zero.
Can we ask more details on where the ground defect was found and how you are currently setting?
Are you in a campground, at home or other power? And then there was the question of where you were testing for the difference in potential.
Power can sometimes be compared to water. Odd idea but then if we have a water leak, we can make it appear there is no leak if we drain the water away fast enough. Rv and mobile homes have one common problem for power as they both tend to have lots of metal and less than stellar power connections.
So when we are dealing with power questions on both, we need to make sure there is not a "leak" that has energized the metal but we are draining it away fast enough that it doesn't show in tripped breakers and such.
Kind of fishing for an explanation but the problem made not be fixed but only hidden until some point when the ground is no longer good, like when we are disconnected from shore power. That can set up a situation where power from the generator can be leaking to the metal but not bother anything until we happen to step out on a rainy day and make a good ground connection through our body and that is what we don't want.

I fully admit that this may be the odd case of some type of weird induction or other fault and never give any trouble but it's kind of one of those things that we should not take too lightly until we test out things to find what and where there might be a leak.
In other words, you did test and find voltage where there should not have been any but adding the ground makes that voltage go away but does not solve how it was getting there in the first place.
I might try to talk you into a bit more work! If you run the generator without the shore power connected, you will get AC power to almost all the same point as with shore power but not have the RV grounded to actual earth. So my question would be if you still got a voltage reading doing the test the same way as before when you got the 19 volts? If not, I call it fixed but if there is still voltage there, where there should be none, I might want to look further.
Not meaning to badger you into doing too much more but still wondering? Maybe I've been bit too many times and getting gunshy!!! Maybe nothing at all....

mikemakay · 06-15-2020, 08:39 AM

Sorry it took so long for a response, I was busy getting prepared for this trip. I was not plugged into a GFCI outlet. I am at home and have an extension cord from my garage to the coach. When I tested the cord I found that the ground tab of the cord was broken off and the hot and neutral wires were reversed. Once I repaired those problems my coach problem went away. At least I think it did.

mikemakay · 06-15-2020, 08:42 AM

I was thinking of the same test with running the generator without shore power. I will do that this morning and post the results later today. Thank you

Goodspike · 06-15-2020, 08:57 AM

Quote:

Originally Posted by mikemakay

Sorry it took so long for a response, I was busy getting prepared for this trip. I was not plugged into a GFCI outlet. I am at home and have an extension cord from my garage to the coach. When I tested the cord I found that the ground tab of the cord was broken off and the hot and neutral wires were reversed. .

Okay, I think the reversal of H/N is the other issue that could have lead to the problem. You might find that if you disconnect the ground again that the problem would not present itself, that it was a combination of the two. But in any case, that is enough to satisfy my concerns for additional testing, FWTIW.

The generator test might be interesting.