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Duffy

Help Please Caravan Earth Leakage Problem With 230Volt Electrics

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Hi

I had to remove one of my caravan motor mover rollers as i was doing this i received a small electric shock from the roller/mover housing, i had the mains cable connected to my van at the time to keep the battery charged up and i did not disconnect the power cable. I checked with a multi meter from the mover/roller housing to actual ground earth and i got a reading of 60volts. I then checked from the caravan corner steadies again 60volts.

I have just put on four plastic corner steady feet i know this will insulate the caravan from earth but as i see it the power cable should take care of any earthing problems.

I checked with a fault finder inside the caravan into the 13amp socket and three red lights came on on the fault finder indicating that everything was ok.

Can anyone explain what is going on.

Many thanks in advance for any help.

Best regards

John Duffy

 

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Eek! Disconnect from the supply and check the continuity of your EHU cable on the earth pins with your multimeter on ohms. Check the continuity of the EHU earth cable to the caravan metalwork. Check the earth continuity on whatever mains supply socket you're using.

 

TS.

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Just so as someone says it, if you are not sure what to do

get a qualified electrician to look it over and test it.

I wonder why the trips have not operated if the 240V is going

to earth, do you have a proper EHU cable with an earth?

Where is the 240v supply you are using, have you tried the

test button for your 240v supply and test the caravan trips?

Edited by gumdrop
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I had exactly this, some years ago. I found an earth fault with the house socket the ehu was plugged into.

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Probably best to get an electrician with caravan experience, caravans are outside the standardised world of Part P, the basic qualification for domestic electrics.

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I wonder why the trips have not operated if the 240V is going

to earth, do you have a proper EHU cable with an earth?

 

It doesn't sound like any significant current is going to earth. It's probably something like the internal battery charger leaking slightly to earth through noise suppression capacitors, but for some reason it isn't connected to actual mains earth potential.

 

The slight shock the OP received didn't cause enough unbalanced current to reach the 30mA trip limit.

 

While an experienced caravan electrician will sort it I'm sure any other qualified domestic electrician will make sure everything is safe.

 

TS

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After checking the ELCB trips, i would then check that the earth bonding cables are connected.

Ideally the gas pipe, chassis should be connected to the PDU main incoming earth.

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And the earth system is what? There is good reason why in the UK the ESQCR prohibit the use of a TN-C-S system for the supply to a caravan or similar construction. I do question this with home supplies as the gas and electric meter could well be within arms length of the caravan. This has become a problem in charging electric cars out doors. Clearly if the metal of the unit is not at ground polarity then you can get a shock. The idea of having a TT supply to caravan is really not safe if there are items connected to house earth within arms length.

 

In the main out door equipment is Class II that means there is no earth so the caravan is the odd one out.

 

If the shock is due to a live to earth leakage then some where a RCD should trip. Either in the house or in the caravan. But if the DNO's earth has varied from true earth then there is no over current or RCD protection. With a garden shed used by a radio ham as his "Shack" he had a very good earth mat for his transmitter and when the road workers hit the power cable the DNO lost their earth and neutral and the system tried to use his earth in the shed instead. He saw the insulation starting to melt on his earth wire (4mm sq) and turned of all power but to no avail the earth wire still heated up thankfully not part of main supply cable to shed, by time I got there it was a load of copper balls on the ground.

 

Thankfully this is rare only seen it once, all houses but his lost loads of equipment due to getting 415 volts at times rather than 240 (as it was then) and we learnt a lesson and house and shed both moved to a TT supply.

 

However there is a danger if two houses which are close are using a different earth system he was detached so no problem but in the main two semi's must have same earth system.

 

In the caravan site fire regulations mean caravans need around 15 foot between them and a building this is enough of an electrical gradient so building on TN-C-S and caravan on TT is not a problem. But most of us at home don't have that, my caravan is about 3 foot from the house and the gas and electric boxes both earthed to house. So using a TT system is really not safe.

 

Of course you may not have RCD protection and you may have a simple earth fault which should have tripped a RCD if it was fitted. But also it could be more complex. So one would hope any electrician should understand earthing systems and would also have the equipment to test both the earth and the RCD.

 

In my mothers house we found there was no earth. The water and gas had become plastic and the so called electrician had connected the earth wire from the earth rod intended for the GPO party line. The rod and wire were completely inadequate to earth a whole house it was only designed for the telephone. It had years ago had an earth as when I boy I had blown the fuse with an earth fault. However when I came to test there was no earth to whole house and had been that way for years. We should have houses tested every 10 years but unless rented that is rare. We should also test on change of occupant again in the main only with rented.

 

We can get away without an earth for years. That does not make it safe. Clearly you have had a wake up call and it's time to have your house tested. Was called a PIR now called an EICR.

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Well - I sincerely hope that OP can understand the above.

 

Then he can explain it to me :)

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Well - I sincerely hope that OP can understand the above.

 

Then he can explain it to me :)

He may have an earth fault with his household supply.

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He may have an earth fault with his household supply.

About 7 years ago, and having lived in my present home for 20 years I was putting an additional socket in the garage when I found that live and neutral were reveres and probably had been for 30 years prior to that time. For that reason I would check the earth on the socket used.

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And the earth system is what? There is good reason why in the UK the ESQCR prohibit the use of a TN-C-S system for the supply to a caravan or similar construction. I do question this with home supplies as the gas and electric meter could well be within arms length of the caravan. This has become a problem in charging electric cars out doors. Clearly if the metal of the unit is not at ground polarity then you can get a shock. The idea of having a TT supply to caravan is really not safe if there are items connected to house earth within arms length.

 

In the main out door equipment is Class II that means there is no earth so the caravan is the odd one out.

 

If the shock is due to a live to earth leakage then some where a RCD should trip. Either in the house or in the caravan. But if the DNO's earth has varied from true earth then there is no over current or RCD protection. With a garden shed used by a radio ham as his "Shack" he had a very good earth mat for his transmitter and when the road workers hit the power cable the DNO lost their earth and neutral and the system tried to use his earth in the shed instead. He saw the insulation starting to melt on his earth wire (4mm sq) and turned of all power but to no avail the earth wire still heated up thankfully not part of main supply cable to shed, by time I got there it was a load of copper balls on the ground.

 

Thankfully this is rare only seen it once, all houses but his lost loads of equipment due to getting 415 volts at times rather than 240 (as it was then) and we learnt a lesson and house and shed both moved to a TT supply.

 

However there is a danger if two houses which are close are using a different earth system he was detached so no problem but in the main two semi's must have same earth system.

 

In the caravan site fire regulations mean caravans need around 15 foot between them and a building this is enough of an electrical gradient so building on TN-C-S and caravan on TT is not a problem. But most of us at home don't have that, my caravan is about 3 foot from the house and the gas and electric boxes both earthed to house. So using a TT system is really not safe.

 

Of course you may not have RCD protection and you may have a simple earth fault which should have tripped a RCD if it was fitted. But also it could be more complex. So one would hope any electrician should understand earthing systems and would also have the equipment to test both the earth and the RCD.

 

In my mothers house we found there was no earth. The water and gas had become plastic and the so called electrician had connected the earth wire from the earth rod intended for the GPO party line. The rod and wire were completely inadequate to earth a whole house it was only designed for the telephone. It had years ago had an earth as when I boy I had blown the fuse with an earth fault. However when I came to test there was no earth to whole house and had been that way for years. We should have houses tested every 10 years but unless rented that is rare. We should also test on change of occupant again in the main only with rented.

 

We can get away without an earth for years. That does not make it safe. Clearly you have had a wake up call and it's time to have your house tested. Was called a PIR now called an EICR.

Why such a long post?

 

Hes saying check you have a sufficient earth to your house.

You can no longer rely on the gas or water for any earth, not that you should anyway.

 

 

Hi

I had to remove one of my caravan motor mover rollers as i was doing this i received a small electric shock from the roller/mover housing, i had the mains cable connected to my van at the time to keep the battery charged up and i did not disconnect the power cable. I checked with a multi meter from the mover/roller housing to actual ground earth and i got a reading of 60volts. I then checked from the caravan corner steadies again 60volts.

I have just put on four plastic corner steady feet i know this will insulate the caravan from earth but as i see it the power cable should take care of any earthing problems.

I checked with a fault finder inside the caravan into the 13amp socket and three red lights came on on the fault finder indicating that everything was ok.

Can anyone explain what is going on.

Many thanks in advance for any help.

Best regards

John Duffy

Edited by xtrailman

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He may have an earth fault with his household supply.

 

Thank you very much, Had a similar issue in France last year, tingling when touching metalwork. Moved the EHU to another post and all well.

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This has become a problem in charging electric cars out doors.

 

I have a BEV and charge it out of doors.

 

My chargepoint is on the garage wall outside and the sparks did a leak test and did not use the spike I had provided.

 

Is there evidence of this 'problem' please?

Edited by Motobiman

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BEV, battery electrical vehicle. I have heard of earth rods not being effective

due to the soil conductivity or lack of it four rods were used 5mtr. long and

spaced twenty mtrs. apart. People seem to put them in the lee of the building

where the eaves keep the soil dry! this would probably be the reason the sparky

ignored it.

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There is a book (IET) about earths and electric car charging points far too complex for a forum.

 

"I checked with a fault finder inside the caravan into the 13amp socket and three red lights came on on the fault finder indicating that everything was ok."

 

This made me wonder if real earth and house earth may not be same polarity. Just high winds can cause an electrical gradient it does not need to be an electrical wiring fault. Could also be a fault on neighbouring property.

 

The big question is the supply RCD protected? If it is then either a voltage gradient or faulty RCD. If not then answer is simple fit a RCD. Out door supplies have required RCD protection for many years, so I have assumed RCD fitted and working. Although the gradient could be natural it could also be a serous supply fault so needs investigating ASAP.

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. .. I have heard of earth rods not being effective

due to the soil conductivity or lack of it . .

 

I'm just living through this right now. We dug out all the garden topsoil to bring the plot for our new house down to street level. Just quality sand and gravel left but, despite 2 earth rods so far, there are too many ohms, according to the manual. There will be even more ohms when the ground dries out, we are assured. Just as well the sparkies are on fixed price, eh? B)

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And the earth system is what? There is good reason why in the UK the ESQCR prohibit the use of a TN-C-S system for the supply to a caravan or similar construction. I do question this with home supplies as the gas and electric meter could well be within arms length of the caravan. This has become a problem in charging electric cars out doors. Clearly if the metal of the unit is not at ground polarity then you can get a shock. The idea of having a TT supply to caravan is really not safe if there are items connected to house earth within arms length.

 

 

 

I am a caravan owner not an electrician . .. I have no idea what this means . .. am I alone???

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I am a caravan owner not an electrician . .. I have no idea what this means . .. am I alone???

 

Far from being alone, you are probably in the majority! Back to post #3

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I am a caravan owner not an electrician . .. I have no idea what this means . .. am I alone???

 

No you're not alone.

 

John.

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BEV, battery electrical vehicle. I have heard of earth rods not being effective

due to the soil conductivity or lack of it four rods were used 5mtr. long and

spaced twenty mtrs. apart. People seem to put them in the lee of the building

where the eaves keep the soil dry! this would probably be the reason the sparky

ignored it.

No he said it doesn't need a seperate earth as the supply is on the building and the house system was fine.

 

He said a seperate earth is only needed if the chargepoint is on a seperate building like a detached garage or if the house system is not xxxxxxx. Cant remember what it had to be but something to do with the way the earth was on mains water supply or whatever and he bonded the charger to the gas pipe as well.

Edited by Motobiman

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As a frst step,Switch off the supply to the caravan at the supply end leaving the EHU cable plugged in,check to see if voltage still present.
If no voltage then the scource of the voltage is probably within the caravan or EHU cable.
If voltage still present switch off the main incoming switch in your house consumer unit and check to see if voltage is present,if it isnt't then you may have a fault on the house wiring/appliance.
!f it is stiil present contact your DNO as it may be a fault on their neutral/earth conductor and outside your control.
knarf

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DNO. Distribution Network Operator

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DNO. Distribution Network Operator

 

Thanks gumdrop! How stupid I must be, not to know that. I feel such a fool. NOT!

 

 

John. :D

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Many houses these days especially if older than 50 years have had the earth connected to the water or gas pipes in the house somewhere. However gas pipes and water pipes in many cases have been changed to plastic in the house or just outside, so in effect you have no earth, well a poor one.

These days you should either have at least earth conductor of a minimum length 1metre driven into the ground and or the earth cable from the consumer unit connected to the wire armouring of the supply cable coming into the house. this earth should also be connected to your cold water pipe and copper gas pipe, this ensures that should you have a fault with your boiler or any gas/water appliance any current will go to earth irrespective of any plug socket wiring ( belt and braces)

I have had a slight tingle when working on my van in the wet whilst plugged in, I never checked the voltage to earth but the current (Amps) was less than 5mA which is well below the trip threshold of an RCD. The RCD is there to stop you being killed, it is not guaranteed to stop mild shocks.

You may not have a problem at all.

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