Help with testing to find why I'm getting shocked when on EHU

[TravellingSmurff]

Hi guys,
I have a converted crafter that I didn't convert.
When in France the other week, I went on ehu and touched the underslung gas tank and got a shock. Same when I touched the metal in the garage part under the bed.
I do not have an inverter.
I have two UK mains plug sockets
I have a battery charger connected to the ehu

I understand that when on ehu, the chassis and plugs should be connected to the ehu earth and that when I got the shock, I was laying on wet grass and I was the conductor to earth, rather than it going back to the ehu.
How and what do I test? I have a multimeter. And I understand there should be some resistance between the earth on the ehu and the things connected to it, including the chassis. Do I need to make up a long lead, touch the earth on the ehu IN and then start measuring the resistance on appliances?

If you think I should hire someone to have a look, then who and anyone know at what cost roughly?
Taking it back to the people that did the conversation is a possibility but they're the other end of the country and was hoping to save some time, money and effort really.
Thanks for your time
Danny

 

[Rapido925M]

Personally I would unhook carefully from the EHU and wait for someone with deep knowledge to reply

Gordon

 

[Abacist]

I am no expert but the chassis etc acts as Earth for the vehicle 12 volt systems.

I do not believe that the chassis or vehicle parts should be used as Earth for the 240 volt EHU power.

Earth should be the Earth connection at the EHU post and all earths should connect back to that.

If you are getting shocked then there is a mains short/leak to the chassis.

 

[Sue and Rick]

Start at the site supply plug and go from there. Check ehu plugs for loose earth wires then move to the van. As above the 240v should have its own circuitry.

 

[Rapido925M]

OK, having got that concern off my chest I'm happy to give you my suggestions BUT I'm not an expert.

1) Have you got a tester which checks if the wires and earth are connected as we would expect in UK? I have one which I use EVERY time I connect up, even when I'm at home. It is possible that this problem MIGHT be down to what is known as "reverse polarity". That means that the EHU supply is providing 220V to your neutral lead whilst your live lead is acting as the return. Quite often people connect their neutral wire to their earth wire: I THINK this would make your chassis live!

2) If you haven't got a tester, can you borrow one or buy one? Are you on a campsite or at home? Are there any people who can help?

3) It is possible (and safe) to connect your multi-meter on 600V VOLTAGE setting and use it to see if the potential difference between the EHU terminals are what you expect. OBVIOUSLY it requires care on your behalf. IF you don't know how to do it, don't try it!

4) IF reverse polarity is the problem, most of us carry a little adapter (often home made) to change the L>N and N>L. If on a site, someone might lend you theirs. HOWEVER, if you are on a continental site with two-pin connector, you may achieve the correct polarity by simply reversing which pin goes into which socket ie turn the connector around!

Good luck - Gordon

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[Tigger-Tim]

I would expect the van body to be connected to earth. And for there to be an RCD fitted. That RCD should trip when you press the test button.

I'd trace the wiring through from the inlet to the sockets, making sure that they were all connected properly, and that the earth was connected. Don't forget to also test the cable you used to connect to the site power.

But if you're not confident with electrics, I'd get a workshop to check it out - an hour of their time is a bargain if the alternative is getting electrocuted.

It is possible that your van is fine, and this was caused by a faulty earth at the French bollard (ie. the earth on the bollard had mains voltage on it).

 

[ChrisL]

You can get testers with simple lights to tell you what your connection is like, here's mine.

 

[Widge]

Remember, in france and possibly other european countries you cannot guarantee live and neutral are the expected way round, this shouldn't make a difference if the van is wired to take that into account, but unless you know what you are doing i would certainly get an expert to look at it.

 

[Richard n Ann]

I got a tingle off some cable tray once. Turned out the vac pump was running on it and the extension cable had lost it's earth. Check the earth on the EHU lead

 

[St3v3]

Sounds to me like the earth pin on your EHU isn't getting an earth from the supply.

Or you wear polyester clothes, really thick rubber shoes and comb your hair a lot.

(You could be full of static and the bits you touched are a good earth.)

Were the shocks a sudden bang and gone or a fast pulsing thing that went on for longer?

You need a decent sparky either way.

Maybe next time you get a shock, immediately touch it again*. If a genuine fault, it will hurt again. If static, it won't.

*probably don't do this, but it would help with the diagnosis

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[rod_vw]

If you don't have the same experience when you are plugged into a known good EHU I would simply accuse the French one of being faulty or wired incorrectly.
I've had the same experience when connected to some French site sockets.

 

[Derbyshire wanderer]

I suspect that the L and N supply were crossed over. Your system has insufficient RCD protection and you need to fit a twin pole RCD.
Get an electrician to test it for earth leakage faults and fit a suitable 2 pole RCD

 

[Gina M]

Hi guys,
I have a converted crafter that I didn't convert.
When in France the other week, I went on ehu and touched the underslung gas tank and got a shock. Same when I touched the metal in the garage part under the bed.
I do not have an inverter.
I have two UK mains plug sockets
I have a battery charger connected to the ehu

I understand that when on ehu, the chassis and plugs should be connected to the ehu earth and that when I got the shock, I was laying on wet grass and I was the conductor to earth, rather than it going back to the ehu.
How and what do I test? I have a multimeter. And I understand there should be some resistance between the earth on the ehu and the things connected to it, including the chassis. Do I need to make up a long lead, touch the earth on the ehu IN and then start measuring the resistance on appliances?

If you think I should hire someone to have a look, then who and anyone know at what cost roughly?
Taking it back to the people that did the conversation is a possibility but they're the other end of the country and was hoping to save some time, money and effort really.
Thanks for your time
Danny

It's good that you are still with us

 

[LUNARBOY]

Hi guys,
I have a converted crafter that I didn't convert.
When in France the other week, I went on ehu and touched the underslung gas tank and got a shock. Same when I touched the metal in the garage part under the bed.
I do not have an inverter.
I have two UK mains plug sockets
I have a battery charger connected to the ehu

I understand that when on ehu, the chassis and plugs should be connected to the ehu earth and that when I got the shock, I was laying on wet grass and I was the conductor to earth, rather than it going back to the ehu.
How and what do I test? I have a multimeter. And I understand there should be some resistance between the earth on the ehu and the things connected to it, including the chassis. Do I need to make up a long lead, touch the earth on the ehu IN and then start measuring the resistance on appliances?

If you think I should hire someone to have a look, then who and anyone know at what cost roughly?
Taking it back to the people that did the conversation is a possibility but they're the other end of the country and was hoping to save some time, money and effort really.
Thanks for your time
Danny

I have 50 years experience in electrical contracting and I would recommend employing a qualified electrician to test and inspect your installation, it might well be something quite simple to rectify but in the meantime stop using ehu.

 

[herald_400rl]

I had this, we unhooked and once home I got the multimeter out. First, visual inspection and then I tested continuity in the EHU lead, all good. Then, on the van socket, all good. Next followed the cable to the vans internal electric box, nothing. My break was there, the earth had wiggled out the back of the terminal.

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[Pausim]

Quite often people connect their neutral wire to their earth wire

That sounds lethally dangerous, why would anyone do this? We all know that polarity is a UK thing and that on the continent the polarity is often either way round.

 

[Lenny HB]

I suspect that the L and N supply were crossed over. Your system has insufficient RCD protection and you need to fit a twin pole RCD.
Get an electrician to test it for earth leakage faults and fit a suitable 2 pole RCD

All RCD's are double pole they work by detecting I balance of current between live & neutral.

 

[Rapido925M]

That sounds lethally dangerous, why would anyone do this? We all know that polarity is a UK thing and that on the continent the polarity is often either way round.

NOT MH RELATED: I came home one evening and my neighbour was complaining about getting shocks from his cement mixer (trough his thick rubber boots).
Eventually I worked out that the problem lay with his extension lead. To save money he made one himself using TWO CORE flex. He had connected the neutral wire to earth at both ends "because that is what the power company do - connect earth to one phase to give the neutral effect". OK: not sensible but understandable.
Unfortunately, he'd then cut through the cable accidently and used a bit of "school-boy science": connect red to black and black to red. He didn't want to explain why he thought he'd cut through just at the point where the wires changed colour!

IF you haven't worked out the consequences of his error, power was coming in via the red wire, changing into the black wire at his repair and then being connected to the earth at his socket. Then, of course, it went into the metal frame of the cement mixer.

Gordon

 

[TravellingSmurff]

First I want to say thank you for all the comments. Cheers
I'm back home in the UK now. I just didn't try any ehu for the rest of the trip
I ordered one of the plugin testers and will test today.
I asked about the polarity thing on the French site and that wasn't the case this time. But I didn't know about that at the time. I since have ordered some cables from ebay.
I agree about the electrician, however I wanted to do the basic continuity tests myself first to learn and second to save some time, which hopefully will save some money too. However, I fully appreciate the "leave it to the experts" comments
I will update when I have had a look
Thanks again everyone

 

[Tigger-Tim]

First I want to say thank you for all the comments. Cheers
I'm back home in the UK now. I just didn't try any ehu for the rest of the trip
I ordered one of the plugin testers and will test today.
I asked about the polarity thing on the French site and that wasn't the case this time. But I didn't know about that at the time. I since have ordered some cables from ebay.
I agree about the electrician, however I wanted to do the basic continuity tests myself first to learn and second to save some time, which hopefully will save some money too. However, I fully appreciate the "leave it to the experts" comments
I will update when I have had a look
Thanks again everyone

They are a useful tool but don't give the full picture - most passive plug in testers will not tell you if neutral and earth are swapped. And they won't tell you if the van's body is seeing live voltage.

If you're testing continuity, I'd start at the cable. I do PAT testing for the local steam railway, and the majority of faults we find are extension leads - they can have a tough life.

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[pappajohn]

France.......no earth at the hookup post.
A short to earth can't trip the breaker if there's no earth.
Have you tried it since at another post or campsite.

 

[xsparks]

Mine does.

 

[xsparks]

The plug in mains tester that is.

 

[mitzimad]

surely the incoming 240 should be earth bonded to the vehicle chassis to prevent this

 

[autorouter]

All RCD's are double pole they work by detecting I balance of current between live & neutral.

Almost always true, but here in the UK we've managed to make even an RCD single-pole. Some RCDs and RCBOs are wired so that the live and neutral are compared to detect imbalance. Then, guess what, they only switch off the live if imbalance is detected. Sometimes you just can't make it up

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[EML]

You're on the right lines doing your continuity test, but finding earth faults is difficult if you just have a multimeter. You need a PAT tester, which comes in at about £200-£300. Your local electrician can come around and check the van quickly and cheaply, and lots of people make a living testing equipment on commercial premises.

While you've got the electrician, ask him/her to check your RCDs. If you're going back to the continent you need one which has circuit breakers in both line (ie. 'live') and neutral (in other words, a 'double pole RCD'). If the rest of your wiring is good, this doesn't matter, but if you have a fault, it does matter. You don't need a cable reverser if you have no faults and/or a double-pole RCD, but it doesn't hurt to have one.

Some other points:

1. Neutral and earth are connected somewhere in the system, probably at the substation, so you can't test for N/E reversal, however expensive your tester
2. Cheap plug-in testers will tell you if you haven't got an earth connection, but can't tell you if you've got a poor or intermittent connection, which sounds like your problem
3. The other thing cheap testers can't do is tell you if you've got a "supply reversed" issue. Confusingly, this is also called "polarity reversed". All testers will tell you if you've got L/N reversed, but this is a more specialised situation, where the supply L is connected to both your local N and E. Not worth worrying about, but causes confusion in other threads
4. The incoming E to your van must be connected to your chassis - an earlier poster on this thread was confused about this

 

[TravellingSmurff]

France.......no earth at the hookup post.
A short to earth can't trip the breaker if there's no earth.
Have you tried it since at another post or campsite.

I tried it on another post on the same campsite. Annoyingly I didn't think of trying another cable. I didn't try anything after that. I stayed on battery for the rest of the trip and haven't tried since being home yet.

Is there a way of testing without having to touch and get electrocuted? Maybe set the multimeter to volts and place the black lead to the ground?

 

[TravellingSmurff]

You're on the right lines doing your continuity test, but finding earth faults is difficult if you just have a multimeter. You need a PAT tester, which comes in at about £200-£300. Your local electrician can come around and check the van quickly and cheaply, and lots of people make a living testing equipment on commercial premises.

While you've got the electrician, ask him/her to check your RCDs. If you're going back to the continent you need one which has circuit breakers in both line (ie. 'live') and neutral (in other words, a 'double pole RCD'). If the rest of your wiring is good, this doesn't matter, but if you have a fault, it does matter. You don't need a cable reverser if you have no faults and/or a double-pole RCD, but it doesn't hurt to have one.

Some other points:

1. Neutral and earth are connected somewhere in the system, probably at the substation, so you can't test for N/E reversal, however expensive your tester
2. Cheap plug-in testers will tell you if you haven't got an earth connection, but can't tell you if you've got a poor or intermittent connection, which sounds like your problem
3. The other thing cheap testers can't do is tell you if you've got a "supply reversed" issue. Confusingly, this is also called "polarity reversed". All testers will tell you if you've got L/N reversed, but this is a more specialised situation, where the supply L is connected to both your local N and E. Not worth worrying about, but causes confusion in other threads
4. The incoming E to your van must be connected to your chassis - an earlier poster on this thread was confused about this

>The incoming E to your van must be connected to your chassis - an earlier poster on this thread was confused about this

This is interesting and seems divided on this whole forum. I thought this was the case because anything metal can be conductive and I assume having it connected to ehu earth was mean that is a better conductor that a human and therefore be good for safety. assumption, not an electrician
Thanks

 

[Jev88]

First place I would look is DISCONNECT EHU and look inside the Motorhome socket, the wiring there may be loose or frayed after the usual bumping and bouncing from driving down the road. I have seen some internal connections pulled quite tight.

 

[autorouter]

I ordered one of the plugin testers and will test today.
I asked about the polarity thing on the French site and that wasn't the case this time. But I didn't know about that at the time. I since have ordered some cables from ebay.

I have an adapter from round blue plug to UK 13A socket. With a plug-in tester I can use it to test the hookup post. It shows up a reversed polarity problem, but it also shows up other faults like missing earth. Then I can plug it into the end of the hookup cable to do the same checks, to be sure the cable is OK. Then when the hookup cable is connected, I can check the motorhome sockets for the same problems. It's all quick and easy if you have the adapter.

You don't get the whole story, as Tigger-Tim says, but it shows up a missing earth.

By the way, I noticed in France this week that Lidl are selling a '2-pin plug' mains tester for testing French/German sockets.