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Domestic Caravan and tncs

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The other day I had to connect a static caravan so the house holders can live in it while their house is being refurbed, the house is tncs
no I know your not ment to export the earth and I understand why, so I installed a earth rod, 78 ohms.
the main board in the caravan has 30ma rcd, but I could not bring my self not to connect the 3rd core in the swa to bring the earth fom the house also. I know the situation that if the dno's neutral fails this earth could end up running the neutral to the house etc.
but what's worse? This earth, now become neutral burnt in the swa or, some one leaning on the outside of the caravan, which would be at 230v with the dno's neutral fault and stood on the ground, possible wet?
they would then complete the circuit from the bonded caravan through them to ground and back to the supply transformer or dno's next earth spike.
any comments?
 
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  • #2
After thinking about it, I see the error in my thinking, the only reason the caravan body could become live under the fault is because the voltage would be carried up the earth wire. I see now why it's better not to connect the earth and only rely on the earth rod, as this way it'd be separated. This has been a lesson to me and I hope others can learn from it. Sometimes you just need to stand back and think about the wiring system as a whole.
 
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  • #3
Why no reply's is this such an easy situation? I can see the answer now but surely other people have had to think about this and maybe been stuck.
 

Jimmy Boy

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Arms
You knew you shouldn't have done it..you did it..now you want a pat on the back for informing us ? are you for real ? you seem to be a spark you have the regs book what do you want anyone to say ?..congrats ?

J
 
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  • #5
Ref jimmy, us? What's that all about, is this forum all for you guys that have been on here a while and new people like me are seen as outsiders? I've seen soe of te comments people receive on here and I think it's disgusting. Who do people lie you think you are
 
1

1shortcircuit

Everyone take a deep breath and...... Chill:thumbsup

There are various threads discussing the exporting the earth on a tncs and from what I can gather there are many differences of opinions for and against.

Why you have received no comments I am unsure but I have a feeling that this thread will either become closed by the Moderators OR turn into another posting frenzy starting the arguments all over again.
 
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sedgy34

I will start by saying don't reply to your own post as people don't comment

And the pme? It says not to export but sparks do it because they can argue it in court if they ever got in there
i like a good reading on the earth so may have done the same, also I've never come across or read about the DNO loosing a neutral. (tin hat on) lol
 
D

Deleted member 9648

Bs 7671 states that if a TN system is used to supply a caravan it shall be TNS...it also states that the ESQR prohibit the use of a TNCS system to supply a caravan.
It's quite clear in 708.411.4....Therefore if you connected a TNCS earth to a caravan and the unlikely accident occured you would be in deep doo doo.
This has nothing to do with general 'exporting the earth' nonsense which gets spouted as soon as outbuildings are mentioned......TNCS is only prohibited in a few of the special locations listed in section 7.
 

richy3333

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LOL, I like the way you had a little chat with yourself. I do that in my head all the time :)

You need to remember that BS7671 is not a Statutory Instrument, i.e. LAW, however in the event of a problem they will beat you around the head with the book (whoever 'they' are).
ESQCR is a Statutory Instrument. That means it IS LAW. i.e. go against it and you have broken the law and they take your pants down, spank you big time and ride you like a whore!

I only scan read your post and couldn't decide if you had TT'd the install or used the DNO earth. If you did break the law, I wouldn't be shouting about it on an open forum, and in such circumstances good luck with the certificate.
 

richy3333

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Just re-read you post are you saying you have used the DNO earth and also an earth rod :confused:
 
A

ayjay

thats what the poster said richy (i think) he used an earth rod but alsoconnected the earth in the armoured as well
 
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drew35

I suppose that whole chapter on caravan's in the big green book is just there to pad it out maybe?
 
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1shortcircuit

I suppose that whole chapter on caravan's in the big green book is just there to pad it out maybe?
I must admit, it's one I skip but then again... I don't work on caravans lol

I hope this thread continues nicely as I'm following with a keen eye in the hope that I will learn something new and have a few little chuckles along the way :)

:thumbsup
 

richy3333

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It's dead simple, the OP just needs to follow the Regs in the BGB.
You're not allowed to use the DNO earth on a temporary structure. Separate the two and provide your own means of earthing, n'est pas?
 

Jimmy Boy

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Arms
Ref jimmy, us? What's that all about, is this forum all for you guys that have been on here a while and new people like me are seen as outsiders? I've seen soe of te comments people receive on here and I think it's disgusting. Who do people lie you think you are
My reply may have been blunt..but I stand by it lets reread your OP...

The other day I had to connect a static caravan so the house holders can live in it while their house is being refurbed, the house is tncs What does the caravan section say in the regs ?

no I know your not ment to export the earth and I understand why, so I installed a earth rod, 78 ohms. What has exporting earth got to do with it ? you understand what ?

the main board in the caravan has 30ma rcd, but I could not bring my self not to connect the 3rd core in the swa to bring the earth fom the house also. I know the situation that if the dno's neutral fails this earth could end up running the neutral to the house etc. So you completely ignore the regs, do as you think fit ?

but what's worse? Someone might die ? is that bad enough for you ?This earth, now become neutral burnt in the swa or, some one leaning on the outside of the caravan, which would be at 230v with the dno's neutral fault and stood on the ground, possible wet?
they would then complete the circuit from the bonded caravan through them to ground and back to the supply transformer or dno's next earth spike.

any comments? Yes if your carrying out electrical work only do that scope of work you are compatant to do, clearly in this case you are not, and in answer to your question " Who do you think you are" I am someone who takes great pride in the professional standards that electrical installation work deserves, and don't take too kindly to 'Sparks' that feel they can do as they please just because they 'Can't resist it'

I don't apologise for being blunt electricity kills


J


 
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Paullestrange

Nailed it on the head there JB,i try and stay away from domestic work,but do a lot of site work,hooking up site offices ,now generally we are connecting to a Genny,but the odd occasion we do have a permanent supply,the BRB and the BGB both state,not to use DNOs earth,but provide separate earth fault return path.
 
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Deleted member 26818

I must admit, I'm a bit confused.
If the third core was not connected so as to bring the earth out from the house, how then was the earth exported?
Then of course, there's the armour, was that connected anywhere?
 
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Guest111

reading this thread has just rang alarm bells with me,in a lot of caravan shops they sell adaptors to go from a standard 13A plug top to a BS4343 blue socket in case you need power in your caravan at home.In fact there is a chap near me has a family member living in a van in the garden,connected by the above method,shouldn,t there be a warning about this on the product?
 
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Deleted member 9648

Nailed it on the head there JB,i try and stay away from domestic work,but do a lot of site work,hooking up site offices ,now generally we are connecting to a Genny,but the odd occasion we do have a permanent supply,the BRB and the BGB both state,not to use DNOs earth,but provide separate earth fault return path.
Where does it say that? Which reg are you referring to?

Edit......only got the BRB to hand and check....and it says nothing of the sort.
 
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I have corrected it now, and was just sort of glad that I had worked out why it shouldn't be done, one voice in my head was telling me the lower z readings the better and the other was the regs telling me not to export. I know we should follow the regs and I do take my work very seriously, this is why I posted about it on here, I'm hoping that other people reading this thread can learn a bit from it too. I think it's a bit unfair for other people to be shooting me down in flames, you don't know me or know what my skills are.
shame the regs dont explain a little about why certan regulations are in place.
if this is explained anywhere in there I'm sure I'll hear about it soon
 

richy3333

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Yaba Yaba, I'm sure you're a nice guy, but it's what's safe for the customer that matters. I don't think it's unfair to "shoot you down in flame" - the Regs are easy enough to read (or crayon-in for the hard of thinking).
I don't know you but have a fair assessment of your skills given your original post :(
 
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  • #28
Fair post richy, better change the way I go about things, follow the regs even if unsure why and work out the reasons after. I'm just always want to know why such things are put in place
 

Jimmy Boy

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Arms
I have corrected it now, and was just sort of glad that I had worked out why it shouldn't be done, one voice in my head was telling me the lower z readings the better and the other was the regs telling me not to export. I know we should follow the regs and I do take my work very seriously, this is why I posted about it on here, I'm hoping that other people reading this thread can learn a bit from it too. I think it's a bit unfair for other people to be shooting me down in flames, you don't know me or know what my skills are.
shame the regs dont explain a little about why certan regulations are in place.
if this is explained anywhere in there I'm sure I'll hear about it soon
WTF do you listen to 'Voices in your head' ? and why have A POP at forum members ? you fck up we all do..just move on
 
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  • #30
Voices was a figure of speech. Was going to start another thread about rcds think I'll leave it a couple of days now
 
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sedgy34

So pretend the caravan is a garage with a light and a socket in there you all now or have been installing earth rods for this?
 

Jimmy Boy

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Arms
Exporting the Earth on aTNCS/PME has been comprehensibly covered on this forum, in fact a PDF is available for this purpose,Will I feel I may be coming across as making a personal attack on you, this is not my intention, but I don't have much patience for people that blatantly disregard the regs and potentially put lives at risk...

J
 
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Edd

Reading this Thread it does seem people were getting a bit personal, and thats a shame.
This is such a great forum but when people have to worry about getting bulled by what they post it will weaken the great varitey of posts.
We all screw up and make mistakes, we all sit back and think "wonder why this is done like this" Hence this thread, and learning begins!
But to attack people when they post is a shame, and polite conversation is a much better to learn by.
And how boring would it get if we all knew the answers, no questions, no conversation.. Boring boring boring
"Tin Hat on"
 

richy3333

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^^^ Fair point but the thread wasn't a 'I wonder why...' It was a 'ignore the Regs, do what I want and then ask questions' thread. To be fair I've seen far worse written on this forum, perhaps some people just need to have a thicker skin?
 
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sparks1973

So pretend the caravan is a garage with a light and a socket in there you all now or have been installing earth rods for this?
except you can extend the equipotential zone out to a garage cant you sedg.....can you extend PME out to a caravan eh?....come on...thats the very thing the O/P has gone and done....and been pistol whipped for it in here....
 

ruston

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Do'nt worry about it to much mate , you had the [email protected]@'s to bring your mistake into the open and the same to admit you were wrong . Many would just hide their mistakes and carry on , at least you asked , and thats one way to learn. so the next time you ignore a reg that you know , you know what you are in for lol.
 
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Paullestrange

Okay not in so many words 740.414.4.
We still however,have to provide a Protective conducter,so are we not infact installing a separate Protective conducter.
 
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sparks1973

do you mean for the caravan or the sub to it?...if the caravan then what your looking to acheave is a seperate earth from the house C/U....hence a rod/s....you would earth the armouringgs of the sub at the upstream end only and arrange it as such that it cannot come into contact with exposed and extranious at the downstream end (caravan)....
 
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Paullestrange

This is all very interesting ,i love a good debate.
I think regulation 542.1.8 in the BRB,sums this up very well,and would be interested how you guys interpret this Reg.

Sparks 1973 is on the money.
 
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sparks1973

you would of course be RCDing the caravan....as the sub will still be a TN...you would not have to RCD it if using armoured......you could of course feed it through a 100mA s type (for discrimination) if you feel so inclined.....
 
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  • #45
The circuit is now as follows, 4mm, 3 core swa from 32a brwaker off non protected side of house cu, armouring earthed by earth nut in here (3rd core also earthed) cable buried entering underside of caravn to plastic adaptable box, live and neutral connected to original caravans twin and earth which must have ran in where it was previously installed. In adaptable box swa is terminated with gland and nut etc but not connected to anything else, 3rd core marked with green and yells sleeve and terminated into connector block, cpc in twin and earth terminated into another terminal block, sticker in box lid saying "do not connect cpc, tt only" earth rod now connected to caravans met via 16mm earth conductor
 

ruston

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Mmmm I think i would have tied the third core to the armoured or not connected it to the supply earth , leaving a potential to connect to pme to anyone in the future who dose'nt know the score is as bad as connecting it yourself. What if your markings fade etc.
 
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  • #47
That's a good point, the label is on the inside of the adaptable box so should be ok. The caravan is only there while the house is being done up, then the cable may by used to run a few outdoor sockets on a radial.
 
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sparks1973

yep...was thinking that ruston when reading will`s last post....would have been better stabbed into an earth nut in the plastic adaptable box....out of sight ..out of mind n all that lot....
 

ruston

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That's a good point, the label is on the inside of the adaptable box so should be ok. The caravan is only there while the house is being done up, then the cable may by used to run a few outdoor sockets on a radial.
Not wanting to dwell on it but temporary installations require the same consideration as .......................
 
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sparks1973

Not wanting to dwell on it but temporary installations require the same consideration as .......................
oh aye....i`v heard that a few times....`oh well its only for a while` n words to that effect.....so with that in mind...another one to bare in mind is a fault will reach full potential on the first quarter cycle.....the point i`m making is it only takes a fraction of a second for a dangerous potential to appear....and if theres no built in fault path for it to take..........it will go for the next fault path that becomes available....in other words straight through you....
 
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  • #51
What I ment by that is the label inside the box won't have faded by the time the caravan is removed. Not that you should cut corners due to the work only being tempory
 
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StuSpiers

Mmmm I think i would have tied the third core to the armoured or not connected it to the supply earth , leaving a potential to connect to pme to anyone in the future who dose'nt know the score is as bad as connecting it yourself. What if your markings fade etc.

I would have done the same.

But certainly not for the same reason, anybody that doesn't know the score is not competent so....... blah blah blah blah blah
 

ruston

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I would have done the same.

But certainly not for the same reason, anybody that doesn't know the score is not competent so....... blah blah blah blah blah
Aye but they have a go regardless . All you can do is make yours as safe as you can lol.
 
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  • #54
I think it's time this thread came to its end, it's the first thread I've posted, I wish to thank the helpful people for their comments, shame about the unhelpful/rude ones but I suppose that's just the way folks are.
cheers people
 
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ayjay

don,t take on will,! iv,e only been a watcher of this forum for about a year-
ive been a sparky for 44 ****ing years
these, or some, are pompous ****s
they learn ze and zs but cant hit a cows arse with a shovel
 
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1shortcircuit

don,t take on will,! iv,e only been a watcher of this forum for about a year-
ive been a sparky for 44 ****ing years
these, or some, are pompous ****s
they learn ze and zs but cant hit a cows arse with a shovel

???:17:
 
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1shortcircuit

A shovel won't fit in my toolbag, Perhaps that is where I am going wrong;)

***Posted in jest as I am not sure how to read post 55 correctly***

:thumbsup
 
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  • #60
Night night then, cheers to all the helpful folks
 
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