Camper trailer power question - tingly feeling!

Submitted: Sunday, Aug 10, 2014 at 16:59

ThreadID: 109093 Views:6796 Replies:8 FollowUps:11

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Wayne P5

Hi all,

LONG time since I've last posted here, but hoping that the brains trust on here might be able to solve a problem that I've got with my camper trailer (2010 Kimberley).

I seem to have an electrical issue of some sort. When the camper is plugged into 240v, I get a tingle in the sink through a small cut in my hand. This was first noticed when camping at Easter time, and the electrician that looked at the trailer couldn't find anything wrong and therefore got Ergon onto the case, assuming there was a floating voltage of some sort at the campsite.

Right now we are camping again, at a different campsite and the same issue is happening. This time the tingle seems stronger, possibly due to rain we had last night making the ground wet. Just had another sparking look at it and he too felt it was nothing major and couldn't find the direct cause. However it's so strong that I cannot keep my hand in the washing up water!!!

I know there's simple things I can do to prevent being shocked, such as wearing shoes etc, but I really want this issue fixed, once and for all - especially with a couple of kids running around.

I notice the 'tingle' when:
- I thought it was only when connected to 240v, but I can feel it faintly when the power is fully unplugged (ie, on 12v). It is MUCH worse when connected to mains power...
- it is a strong tingle even if the safety switch on the camper has been tripped (note, the safety switch has never actually tripped, I turned it off to see if it made any difference).
- turning off all power consumption devices makes no difference (fridge unplugged, all lights off etc)
- disconnecting solar makes no difference
- turning inverter off makes no difference
- the entire camper appears to be 'charged' - it's just most noticeable when my hands are immersed in water.
- electrician says there's only 1v, however the power of the tingling sensation seems to change throughout the day (load on the grid?)

The electricians have checked the power cable. Say it's ok. The earth to the camper chassis looks good (to me). Both electricians visually checked wiring etc.

Does anyone have any ideas/experience in troubleshooting issues like this?

Many thanks
Wayne

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Reply By: Sir Kev & Darkie - Sunday, Aug 10, 2014 at 17:30

Sunday, Aug 10, 2014 at 17:30

Try a different power lead to connect to 240v and see if that fixes the problem.

Cheers Kev

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AnswerID: 537488

Follow Up By: Wayne P5 - Sunday, Aug 10, 2014 at 17:41

Sunday, Aug 10, 2014 at 17:41

Hi Kev,

I tried the next door neighbors - same result. That's not to say they're both buggered! The sparkies also checked the cord and have it the thumbs up...

I might invest in a new one anyway.

FollowupID: 821723

Reply By: Ross M - Sunday, Aug 10, 2014 at 17:32

Sunday, Aug 10, 2014 at 17:32

Have you tried with the sink earthed to the camper chassis?

Is the camper chassis definitely connected to the earth line of the 240v?

AnswerID: 537490

Follow Up By: Wayne P5 - Sunday, Aug 10, 2014 at 17:43

Sunday, Aug 10, 2014 at 17:43

Hi Ross,

Every bare metal part gives a tingle - it's just most noticeable when I'm washing up and standing on wet ground (it rained last night).

I've since disconnected the power fully...

The tingle I feel when the 240v is completely disconnected is making me think it might be the inverter/battery charger??

FollowupID: 821725

Follow Up By: Ross M - Sunday, Aug 10, 2014 at 19:38

Sunday, Aug 10, 2014 at 19:38

DO you have a 12v compressor fridge?
Many of them use an inverting device ie switching 12 to a higher voltage? Engel do have this way of working and the oscillating compressor runs at around 22vAC.

Not sure how you would feel that though.

Allan B might be able to cast a light on that.

FollowupID: 821737

Reply By: Slow one - Sunday, Aug 10, 2014 at 18:09

Sunday, Aug 10, 2014 at 18:09

Wayne,
if you are sensitive to 12 volts dc you will get quite a tingle when your hands are wet.

I can feel 12volts quite easily if I lean on the body of a vehicle and touch the + of a battery.

You may have a battery problem rather than a 240v problem. With 240volts charging the battery, the voltage will be higher the battery which may cause the increase in the tingle strength.

Pull the battery leads and then see what happens.

AnswerID: 537494

Reply By: Allan B (Member, SunCoast) - Sunday, Aug 10, 2014 at 18:09

Sunday, Aug 10, 2014 at 18:09

Hi Wayne,

Yes, I do have experience of the situation you describe. I am an electrician/electrical engineer.

My first reaction to an expression of a "tingle" is to say 'stop using it and have it examined by an electrician' but I note that has already been done, twice, with no fault found.

So now it is down to a situation where the earthing system of the 240v supply is sitting at a few volts above the actual ground that you are standing on. This may as little as several volts to be felt in the 'right' situation and is particularly felt where contact is more intimate such as a cut on the finger. It is not necessarily unsafe but is uncomfortable and concerning. Some people are more sensitive than others to this. It is not an unusual occurrence but is usually only observed when you have close contact with the soil such as bare feet.

The supply system may well be connected to an earthing stake at the main switchboard but current flow can introduce a small voltage drop in the earthing conductor which produces a few volts difference in the voltage between the earth wire connected to your camper and the soil that you are standing on.

There are only three ways to overcome this situation:
1. Use an isolating transformer between your camper and the supply. This is rather impractical and expensive.
2. Insulate yourself from the soil with appropriate shoes or a rubber mat.
3. Locally earth your camper with an earth stake driven into the soil for maybe 20cm and watered. An alternative could be to have an earth wire connected to the camper frame which is clipped to a nearby metal water pipe, but this is not always available.

The "faint tingle" you feel through the small cut on the hand can also be a sensation felt due to an electrochemical reaction rather than a true electrical current flow. This could explain why you feel the reaction faintly when the power cable is disconnected.

As the sensation diminishes when the supply is unplugged it indicates that it is mains related and not your inverter. But to be sure, shut the inverter down also when investigating.

Cheers
Allan

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AnswerID: 537495

Follow Up By: Wayne P5 - Sunday, Aug 10, 2014 at 18:55

Sunday, Aug 10, 2014 at 18:55

Hi Allan! You're a legend. Thanks for the reply, and for putting it in layman's terms that I can understand!

I can only feel the sensation when in bare feet, and last night it rained so the ground was wet too. The gash on my finger is quite deep too which isn't helping the situation...

I tried a makeshift earthing point today with a tent peg and jumper lead wire - some, but not much difference.

I also tested my finger in the sink (tingle!) vs water in a plastic bowl (no tingle.

Thanks for your feedback. It makes sense, and could also explain why I don't feel the same sensation at home (possibly a better earth?)

Cheers,
Wayne

FollowupID: 821732

Follow Up By: Allan B (Member, SunCoast) - Sunday, Aug 10, 2014 at 19:42

Sunday, Aug 10, 2014 at 19:42

It is also quite possible to experience this within a home environment too. Most particularly at the washbasin when in bare feet.
My guess is that when the small voltage is applied via a cut the nerves are more exposed and experience the current. But I have yet to discover a learned text on the subject.

A similar experience occurs when the inside of the wrist is very lightly brushed across a metal object which is 'live' by only a volt or two. I have often used this technique when testing for leakage.

Your "finger in the sink" test confirms what I have been saying.

The tent peg was probably too small to make adequate earth conductivity.

Even a pair of thongs should insulate you sufficiently.

Cheers
Allan

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FollowupID: 821740

Follow Up By: Ross M - Sunday, Aug 10, 2014 at 20:54

Sunday, Aug 10, 2014 at 20:54

Although sort of unrelated. When it is dry weather and at Wilpena Pound Camp ground, the shower block used Single wire earth return. Might still be like that.
When you had a shower you became part of the earth return via the salts in the water and the connection back to the generator because the ground wasn't wet enough to be a good conductor.
Bodies under the spray of the shower assisted in completing the circuit.
Although I didn't notice the lights get brighter I definitely was in synch with the AC power source.

You tingled all over and it wasn't from excitement or the cold.

FollowupID: 821749

Follow Up By: Member - John and Val - Wednesday, Aug 13, 2014 at 07:53

Wednesday, Aug 13, 2014 at 07:53

I like Allan's suggestion that there could be a small voltage difference between the ground you are standing on and the ground where the mains supply is earthed. That mains supply earth is connected to your trailer via the power lead. This could be easily checked by temporarily disconnecting the power lead from the trailer and doing a tingle test.

Oh....... and I'm assured that it isn't a good enough excuse to get out of washing up!

Cheers

John

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FollowupID: 821839

Reply By: Tony H15 - Sunday, Aug 10, 2014 at 19:36

Sunday, Aug 10, 2014 at 19:36

When testing, turning off an appliance is not enough, the appliance should be disconnected either by pulling the plug or by disconnecting wires. You should also ensure you are not feeling the effects of static electricity by not wearing polyester based clothing when testing.

Most appliance will have at least one capacitor in circuit, if your appliances are still plugged in you may be getting a boot via capacitor discharge. Very unlikely though as capacitors will only hold a charge for around eight minutes and when they do discharge they discharge completely. So if you have unplugged or disconnected all 240v appliances and unplugged the 240v lead from your trailer, at most you will get one boot only.

If all 240v appliances are disconnected, unplugged and all capacitors discharged , it is not possible to get a boot through the 240v system, even if one or all appliances is faulty. Given that, the problem then will more than likely be coming from the 12v system. Ideally, all 12 volt systems should have separate earths for each appliance and each earth should lead straight back to the battery (or nearby terminal bridge) - earthing through the trailer, while not good practice, is a much favoured practice of most trailer and caravan manufacturers.

You should disconnect all earth connections, clean them and their attachment points and re-attach. Do the same for any terminal bridges and any other connectors. Manufacturers tend to twitch bundles of wires together and bind with insulation tape; again, bad practice. If you find any bundles bound with insulation tape, take apart and install a terminal bridge.

For an emergency fix you can make an earth spike, wire it to the trailer and hammer the spike into the ground. Buy a multimeter ($10 from Jaycar or Supacheap), make yourself familiar with it and carry in your camper - invaluable for electrical problems.

Don’t, mess with 240v systems - big boot…

AnswerID: 537502

Reply By: olcoolone - Sunday, Aug 10, 2014 at 21:31

Sunday, Aug 10, 2014 at 21:31

This very common and quite normal through a cut as..... The outer skin has a very high resistance and an open cut has lesser resistance...... Common on household taps.

If you were getting tingles through the outer skin there could be a concern but an RCD would trip if it was a problem.

Some people have a naturally low resistance compared to others.

If an earth leakage test came out OK not much you can do and it's no concern.

AnswerID: 537521

Reply By: Bob Y. - Qld - Sunday, Aug 10, 2014 at 21:40

Sunday, Aug 10, 2014 at 21:40

Wayne,

Some years back, we had an old Telstra (by its age probably a PMG asset :-) ) enclosed trailer, containing an old Lister diesel with Dunlite alternator. The single cylinder diesel used to rattle and shake the trailer while it was going. One year, the staff started to complain about getting shocks while showering, and washing up, so did some investigation.

At some stage, a previous owner had run the AC output cable through the side of the trailer, sans any conduit, and the vibrations of the trailer had worn through the cables, "lighting up" the trailer frame........and the shower :-)

Think I'd be doing a complete check of all the wiring, in case this is a similar one to the example above. Or else wear pluggers when you're washing up.

Bob

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AnswerID: 537522

Follow Up By: oldtrack123 - Tuesday, Aug 12, 2014 at 20:28

Tuesday, Aug 12, 2014 at 20:28

HI
Not much I can add
Allan has explained what is happening .
Such is very likely happen when ever one is standing in bare feet on conductve material with part of body in water.
Even with ALL power OFF the differences in ground voltages between points can give sufficient voltage to be fealt

Usually that can be confirmed by breaking part of the circuit such as UNPLUGGING the power extension lead.
If it ground step voltages it should disappear.

If it is not Step voltages, you could get a bigger wack , then the RCD should operate OR you should have a very thorough check.

PeterQ

FollowupID: 821831

Reply By: Wayne P5 - Wednesday, Aug 13, 2014 at 09:27

Wednesday, Aug 13, 2014 at 09:27

Hi All - many thanks for all your replies.

I am now home, and noticed that the 'tingle' is still there :(

I went and purchased an el-cheapo multimeter, as I figured that was safer and better to use than my "calibrated" tingly finger! I also invested in a new 15A cable - but it made no difference to the result. I have run some tests (even though I am not sure what I am really doing)... The results are below.

With 240V, 15Amp A/C connected, chassis to (wet) ground:
A/C: 0.7V, 0.2mA
D/C: 0.16V

When 240V disconnected:
D/C: -0.22V

I have booked the camper into Kimberly for a service and to have the problem fixed - only issue is that they are fully booked up until mid September. So in the meantime, I have 2 questions:

1) (the paranoid parent question!): Are these voltages/amps shown above safe? Can I leave the camper plugged into the mains and not have to worry about the kids touching the trailer?

2) Could this issue damage my batteries? Would you recommend that I do/do not leave it plugged in?

Thanks guys!
Wayne

AnswerID: 537607

Follow Up By: rumpig - Wednesday, Aug 13, 2014 at 09:49

Wednesday, Aug 13, 2014 at 09:49

Wayne,
have you checked the OL forum thread you started lately?...there's a few suggestions on there to consider.

FollowupID: 821846

Follow Up By: Allan B (Member, SunCoast) - Thursday, Aug 14, 2014 at 11:04

Thursday, Aug 14, 2014 at 11:04

Wayne,

The 0.7v ac is of the order you could expect and quite sufficient to produce a tingle if in good contact with terra firma and with a wound connection.

The measured dc voltages could be real and from a number of sources but of little consequence, although dc can also stimulate a sensation in the same circumstances. These dc sources can be hard to identify but can even be electrochemical potentials from such as the vehicle tyres.

To answer your questions, 1) The voltages are not unsafe, and 2) No harm will come to your batteries.

This same situation would be present in many, if not all, 240v installations without risk or being observed (or maybe ignored) It's just that you had the right situation to encounter it and was sensibly concerned.

You can evoke a similar reaction using a AA 1.5v battery with a wet finger touched to one end and the other end touched to the tip of your tongue. Try it if you wish, no harm will come.

Cheers
Allan

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FollowupID: 821875

Follow Up By: Hilux fan - Friday, Aug 15, 2014 at 19:15

Friday, Aug 15, 2014 at 19:15

"1) (the paranoid parent question!): Are these voltages/amps shown above safe? Can I leave the camper plugged into the mains and not have to worry about the kids touching the trailer?"

If your worried about your kids getting shocks, see if you can get an earth leakage trip circuit installed, if it hasn't already got one.

FollowupID: 821960