Slight tickle from siding.

[jim44646]

Was washing trailer yesterday. Had trailer plugged into shore power. Ground and feet were wet. Touched siding with bare hand to wipe a black streak and felt a tickle, wasn't strong like a shock. Can't figure where it would be coming from. Tried meter from siding to ground but didn't get any voltage reading AC or DC. Any ideas.

[mainah]

I know what you are talking about often metals will exhibit a "electrical" feeling I have tried to find out why and have never did find any thing conclusive. One of the best accessories you can buy for an RV is the little 3 light wiring testers they are less than $5 mine is plugged into an outlet in the camper full time and I check it every time I plug my camper in. A DVM is very sensitive and if you showed no voltage to ground you most likely have no issue.

[jim44646]

Originally Posted by mainah

I know what you are talking about often metals will exhibit a "electrical" feeling I have tried to find out why and have never did find any thing conclusive. One of the best accessories you can buy for an RV is the little 3 light wiring testers they are less than $5 mine is plugged into an outlet in the camper full time and I check it every time I plug my camper in. A DVM is very sensitive and if you showed no voltage to ground you most likely have no issue.

Thanks for idea. I happen to have 2 of them. 1 regular and 1 for testing GFCI.

[jim44646]

Originally Posted by mainah

I know what you are talking about often metals will exhibit a "electrical" feeling I have tried to find out why and have never did find any thing conclusive. One of the best accessories you can buy for an RV is the little 3 light wiring testers they are less than $5 mine is plugged into an outlet in the camper full time and I check it every time I plug my camper in. A DVM is very sensitive and if you showed no voltage to ground you most likely have no issue.

Checked all recepticals with 3 light tester. All checked OK. Shore power is pluged into a GFCI and it's not tripping.

[JohnB]

Originally Posted by jim44646

Tried meter from siding to ground but didn't get any voltage reading AC or DC. Any ideas.

Jim, try doing an ohm check between the siding and a known good earth ground that is not associated with the shore line cable ground if at all possible. Metal bucket of water on wet ground or metal stake etc. Granted you should have picked up voltage but it leaves the questions of do I know the siding is grounded?? And do you know for sure the incoming shore line cord has an active ground? Don’t know how you checked it.

The siding should be grounded. I have checked mine before; it is a good path to ground on my camper. Very low resistance and on mine there is a copper ground wire to the frame and a jumper to the siding. All by Sunline.

We had a member here not too long ago that had a 120 VAC stray leak powering up his metal roof from a bad connection in the roof AC unit. It was high resistance leak, but still a leak. His daughter came back from swimming and grabbed the camper handle and was shocked. She became the ground wire. Only happened when the AC was running. Finally traced it down to a skinned wire and his old camper lost it’s siding ground some how.

If the camper siding is grounded and you confirmed the incoming shore line has an active earth ground confirmed by the meter, well then tingle should not be coming from the 120 VAC line. Unless you figured out how to be a better conductor then the ground wire. I have run into stray static voltage in old knob and tube wiring in houses, however it was dry out then too. It had voltage but barley any current. It lit up the inspectors voltage tester, the inductive touch the instualtion type. With all the rain we have had here in Ohio recently, the static must be pretty low right now.

Hope this helps and please report back. These are always learning posts.

John

[jim44646]

OK, I checked, shore power has good active ground. It,s directly into ms new breaker panel. Getting 1500 ohms between a scraped bare spot, under side of trailer, and earth ground. Haven't checked siding grounds yet. Just about to leave for West Branch state park foe a few days. Will look into it more when I get home. Quick look didn't reveal any siding grounds.

[dtstanton]

That tickle should have gone through the ground wire instead of you.

I don't know how your Earth connection was when you checked, but 1500Ω doesn't sound like a very good ground to me. If you can, you might want to check between the cord's ground at the TT end of the cord and the ground rod - contacting the rod itself, and not the bare copper that's clamped to it. Likewise, check from the TT's ground prong to the frame and body skin. IMO, it should be a whole lot closer to 0Ω. If only 33mA of leakage goes through that 1500Ω, you could easily feel it under those conditions. 33mA ain't much.

You might want to check the GFCI as well.
How new/old is it? (They do go bad, and don't always fail completely.)
Has it been replaced or installed recently?
Any doubt of it being hooked up right?
How are the ground connections on the upstream end?

You might want to take time to check all of the connections in the panel that the GFCI is supplied from - particularly the neutral and Earth ground circuits, all the way to the Earth ground itself. Make sure all the connections are clean and tight. If you find a loose/substandard connection in a ground circuit, kill the whole panel that it goes to first (not just that one circuit) and then re-do it.

There is a reason that grounding is far and away the largest portion of the NEC. Personally, I wouldn't take it too lightly. Even a slight shock like this is an indication of a poor connection. I have over 35 years under my belt as an industrial maintenance electrician (shipyards/vessels, mfg plants, communications, controls, chemical plant,etc. up to 38kV) and have seen (and felt) a lot.

...just my $.02 worth.

[bunjin]

I'm no electrician, however a tingle isn't something I'd take lightly either. My on the spot check for me would have been to disconnect the shore power and checked with the back of my fingers the exact location and condition that caused the tingle. If no tingle, then I would suspect the shore power. I then would have the DC activated to see if I get a tingle.

My tingle experience has been with electric drills and moisture (wet ground, aluminum ladders, etc.)

Any electric motors running. They work just fine with faults as stated with my experiences with drills.

I don't trust GFCI. Good to have, but trust no.

I'm not recommending the above procedure, just saying that that is what I'd have done on the spot. In my opinion something is in need of attention very soon.

My .02 cents

[jim44646]

Shore & battery disconnected. Still have 1500 ohm from skin to earth. Meter 0s out when leads are touched. Must have corroded wires somewhere

[dtstanton]

Edited after re-reading. You will probably find a loose or corroded connection. If you can't find a definite culprit, you may want to make new grounding jumpers between the shell and frame. Be sure to continue near-zero reading out to the ground blade on the TT's plug.

You probably have a problem with one of your 110v components that created the tingle in the first place, but the grounding circuit is intended to prevent injury from a major tingle when one of them fails. IMO, the grounding needs fixed first.

[JohnB]

Originally Posted by jim44646

Shore & battery disconnected. Still have 1500 ohm from skin to earth. Meter 0s out when leads are touched. Must have corroded wires somewhere

Jim,

Don't know if you left to West Branch yet or not. Nice campground.

This post may help. It shows how Sunline grounded mine and the ohm readings I had when testing. http://www.sunlineclub.com/forums/f7...ock-11647.html

I agree, 1,500 ohms is a lot. Testing across the hot and neutral which is reading my converter transformer most likely, I only get 384 ohms.

While my big camper has a grounding wire to the skin, to frame and one to the moving slide as there are 120 VAC wall plugs in the slide, I do not remember on my T2499 smaller camper an actual grounding wire between skin and frame. That said there may be enough bolted to the frame of the smaller campers they are counting on that. The slide campers are built above the floor different than the non slide campers.

Maybe start with the shore line cord ground pin on one end of the meter, carry it around with you and probe where you are loosing it.

Good hunting.

John

[Sunline Fan]

Originally Posted by dtstanton

1500Ω

Mind=Blown

Never knew it would accept the ohm symbol as text here...

[dtstanton]

Originally Posted by JohnB

While my big camper has a grounding wire to the skin, to frame and one to the moving slide as there are 120 VAC wall plugs in the slide, I do not remember on my T2499 smaller camper an actual grounding wire between skin and frame. That said there may be enough bolted to the frame of the smaller campers they are counting on that.

Good point. That may very well be the case.

[dtstanton]

Originally Posted by Sunline Fan

Mind=Blown

Never knew it would accept the ohm symbol as text here...

I didn't know what to expect either. <G>

[mainah]

RV's are wired as a sub panel the neutral is isolated from the ground. The power ground is bonded to the frame and the 12 volt wiring. There is an attempt to bond the siding also but this often is not as good as one might think. The first place to look is at is the frame ground wire to the siding if it has any age to it there is a good likelihood that the aluminum is pretty much rotted away due to the use of dissimilar metals. Another issue is the lack of machine screws wood screws do not make for good grounds because they will not stay tight. The points where the panels lap is not a good ground either so that leaves the trim and the trim screws to bond the panels. In theory there should be no reason for the siding to become hot grounded or not but anything is possible. A GFI will sense a hot to neutral fault or a frame ground to earth ground fault with you being the fault they also do not need a ground wire to work, how well do you trust them? The OP was on the right track with the meter and a known good ground if there is no voltage imbalance he’s fine.

[jim44646]

Got to work on my ground wires today. Wires were somewhat corroded along with the grounding lugs. The worst culprit was the lugs were fastened to a rusty frame with a rusted screw. I cleaned the wires, lugs and sanded a spot on the frame. Coated everything with dielectric grease and reattached with a stainless steel screw. Recheck earth to skin and got 0 Ω. Hope that does it for now.

[Wannabes]

Sweet! I was going to say, along with Dale and John, that 1.5K ohms from the siding to the ground is way too much for this sort of set-up. Very glad that you apparently have isolated and corrected the problem. A hot skin is not something to let go unresolved.

Mainah, I think you put your finger on the root problem: dielectric corrosion. The system as designed of tying the siding in to the ground would probably be much less problematic, were it not for this potential complication.

[dtstanton]

Originally Posted by jim44646

Got to work on my ground wires today. Wires were somewhat corroded along with the grounding lugs. The worst culprit was the lugs were fastened to a rusty frame with a rusted screw. I cleaned the wires, lugs and sanded a spot on the frame. Coated everything with dielectric grease and reattached with a stainless steel screw. Recheck earth to skin and got 0 Ω. Hope that does it for now.

Excellent! Well done! That should do for a while.
Glad you got it taken care of before someone got hurt.

Keep in mind that you most likely still have "something" leaking to ground to cause the tickle in the first place. You fixed the "safety net", and that will keep the leakage from going through you. That leakage current is now going through the ground wire as it should. It could be some bad or pinched insulation, maybe some moisture or contamination where it shouldn't be, maybe a defective piece of equipment - TV, radio, charger, etc.

As long as that ground circuit stays intact, you should be safe from shock.

[mainah]

I have been all over mine the main reason was for my ham radio install I did not want any thing unbonded. The only ground to the siding was in one place with a ground lug the aluminum was rotted away to the point that there was a circle around the lug with no contact. The aluminum strips that are on the seams are fairly rugged and with dozens of screws it making it a fairly good contact area. I drilled and tapped the strips used stainless bolts and noalox at the joint. I was not too concerned with the lack of grounding on the electrical end because it would have to be a perfect storm failure possible yes unlikely even more so. The frame lugs can look really rusty and nasty but once removed you would be able to see that if the bolts were tight when new there is still some nice shiny metal under there this was my point in the use of wood screws or sheet metal screws they don't stay tight. By code metal electrical boxes must be grounded with machine screws just for that reason.