Static Charge on trailer

[NCMODELA]

Hi all. I put the low amp charger on the battery on the camper today and noticed after awhile that there was a charge on the trailer because anywhere there is metal I would get a small shock. Is this common? Is this bad or not and where would I start to seeing a fix for it.

The only other time it did this was when the slide motor stuck and the motor would just run but not go anywhere.

Thanks
bill

[Harvard]

Again, just because I could, I parked my 28 Ft Class C under a 6KV single phase line (about 20 feet in height) and measured a very steady 62 VAC RMS (88 VAC peak) from the chassis bumper to Earth using a 10 MegOhm input VOM. This Class C has a rubber roof and non conductive walls (other then metal frame work imbedded in the walls, I think).

[NCMODELA]

I guess what would be interesting is if I still get the hot skin with the charger on away from the lines....unfortunately I didn't bring my charger to the outer banks

[NCMODELA]

And then the charging amplifies it to the 100VAC.

Smkettner, the grounds on the Charger, gift were all good....the only ground I would question is the battery ground as I did not tighten it down wi t have a wrench, just hand tightens it with a good twist.

[Harvard]

NCMODELA wrote:
Crazy harvard.....makes me think about what type of cancer were getting from living near power lines

Personally I do not think there is a problem because it is all around us all the time, not just under power lines.

For example, I have 2 metal filing cabinets sitting here on a wooden floor in my home office. If I take my VOM and measure AC volts from either one of these cabinets to a nearby electrical box (which I know is properly grounded via a ground wire from my power distribution panel) I measure a steady 4.5 to 4.8 VAC.

So it is all around us all the time, some situations having a higher capacitance coupling then others, like your RV.

The main difference between your RV and my SUV is the total conductive (plate) area. You have about 25 X 8 = 200 square foot area where as my SUV has only a 10 X 6 = 60 square foot area. So you are getting a higher voltage then I.

One more thing, the actual peak AC voltage is going to be 1.414 X the Measured VAC (RMS) volts. Once you get up around 25 VAC RMS x 1.414 = 35 V PEAK AC is when you start to feel the tingle from the hot skin to EARTH.

On Edit: I am going to go so far as to say that my 10 VAC is to my 60 SQ FT as your 30 VAC is to your 200 SQ FT.

[time2roll]

Is the charger grounded? I mean does it have a grounded 120v plug?
Use an outlet tester to verify ground is good.
Is the charger plugged into a GFI outlet? I would try this and see if it trips.

Otherwise it may well be the overhead power and will be gone once you roll.

[NCMODELA]

26ft aluminum siding typical height and width. The lines are 3 wires wide 2 tall. I don't know km but it is the smallest transfer lines that are ran, not the giant metal ones. Camper was 20 feet from below the lines and the lines were at least 30 feet above, i think....no ground conducter....it was 100 a volts with charger hooked up...20 to 30 with charger disconnected

[Harvard]

So, for the record:

What is the approximate size of TT (as in L, W and H)?

What is the type of construction (as in aluminium roof and aluminum siding or non conductive)?

Is the high voltage power distribution line(s) single phase (1 wire) or 3 phase (3 wires)?

Is there a ground conductor strung below the high voltage line(s)?

Approximately how high is/are the high voltage wire(s) above ground?

Any idea what the voltage (KV) these wires are carrying?

Thanks for keeping us informed with your feed back.

[mhardin]

This is one of the most interesting threads I've seen. Thanks for posting and thanks to Harvard for the explanation.

[NCMODELA]

Crazy harvard.....makes me think about what type of cancer were getting from living near power lines

[NCMODELA]

Got here. No charge on trailer...special thanks to Harvard for thinking of the obvious.

[Harvard]

Just because I could, I parked my SUV under a 6KV single phase line (about 20 feet in height) and measured a very steady 10.5 VAC from chassis to Earth using a 10 MegOhm input VOM.

[Harvard]

NCMODELA wrote:
Sorry. I fell asleep last night. I took the charger and battery off this morning and the problem did not exist with the ground hooked up. But when I removed the ground there was a charge....not aa much as with the charger hooked up though. Also same results when I hook the battery back up, still some charge but not near as much with the charger hooked up.

A possible explanation as to why the addition of the charger making the problem worse: The charger is plugged into one of two phases of the 120 VAC supply. This 120 VAC phase is going to be either in sync with or out of sync with the high tension distribution line. It is not difficult to imagine that being out of phase could be making a difference. Also, the charger may also be adding inductance to the capacitance equation by virtue of having a step down power transformer UNLESS it has a switching power supply.

There are potentially many many many variables at play which can all be resolved with one properly connected GROUND to EARTH bond.

[Harvard]

campigloo wrote:
Could you have a loose or frayed neutral wire? I would check connections in power panel and look for broken frayed or loose wires any where there is movement, like around slides.

With Alternate Current (AC) shorts in wiring are not required to pass leakage current. Leakage (or stray) current is allowed by capacitive and inductive coupling. If the resulting voltage (chassis to EARTH) were the result of a wiring short then the person involved might not live to talk about the experience. But because the leakage is via a "high impedance" capacitive coupling (be it from high tension wires and/or the battery charger) the AC current through the persons body is not enough to do physical harm nor is it enough to trip a GFCI (about 6 milliAmps, if one were present).

When the Battery Charger is on line and in circuit it would most likely introduce an new capacitance that exists from the DC OUTPUT to the 3 AC conductors (Hot, Neutral and Ground). It then becomes a tug of war between all the sources of stray AC currents which is just one of the less obvious reasons for having GFCIs and 3rd wire grounds in the first place.

[nomad297]

Cool thread.

Bruce