Connecting A Portacabin.

[No1]

I have got a Portacabin to connect up to the mains tomorrow, I have not been to look at the job so I don't know what it entails, and it's been a while since I had to connect one.

What is the general practice to connecting portacabins now, if the supply is PME will I need to tt the Portacabin and put an earth rod in?

Anything else to take into account?

Thanks.

 

[Andy™]

i would TT it, but for fixed cabins, you can use TNCS

 

[No1]

Thanks Andy.

 

[ProDave]

When I built my own house 6 years ago, we lived in a static caravan on site during the build.

Although they gave us a PME supply, the DNO insisted we TT'd the caravan.

Bizarre if you ask me, but that seems to be the regs.

 

[Evans Electric]

If there is no water or gas etc in the cabin why would there be a problem ?

 

[No1]

Just looking in Regs book now, Reg 704.411.3.1 A TN-C-S system shall not be used for the supply to a construction site, except for the supply to a fixed building of the construction site.

Seems to cover what Andy was saying.

 

[ProDave]

Just looking in Regs book now, Reg 704.411.3.1 A TN-C-S system shall not be used for the supply to a construction site, except for the supply to a fixed building of the construction site.Seems to cover what Andy was saying.

So my "static" caravan was deemed to be "not fixed", or was it because it was on a "construction site" that I was forced to TT it?

I know regs are regs, but I would love someone to explain to me how a lousy TT earth can be better, or safer than a TNCS?

 

[Apache]

I know regs are regs, but I would love someone to explain to me how a lousy TT earth can be better, or safer than a TNCS?

ooh brave! Many members on here favour TT over any other earthing arrangements!

 

[Andy™]

So my "static" caravan was deemed to be "not fixed", or was it because it was on a "construction site" that I was forced to TT it?I know regs are regs, but I would love someone to explain to me how a lousy TT earth can be better, or safer than a TNCS?

do a search for 'exporting TNCS' and youll find loads of topics on this, and why TNCS is dangerous (money over safety)

 

[Bez]

So my "static" caravan was deemed to be "not fixed", or was it because it was on a "construction site" that I was forced to TT it?I know regs are regs, but I would love someone to explain to me how a lousy TT earth can be better, or safer than a TNCS?

Lose neutral, you've lost your earth with TNCS

 

[Andy™]

Lose neutral, you've lost your earth with TNCS

more importantly, all metalwork becomes live, and in case of shock, RCD will not trip

 

[ProDave]

Lose neutral, you've lost your earth with TNCS

more importantly' date=' all metalwork becomes live, and in case of shock, RCD will not trip[/quote']Those are both cases for not relying ONLY on TNCS for earthing.

Also very valid points for things like caravans that are made of metal.

But I don't see why exporting a tncs is any worse than any tncs installation in the first place. A house with a tncs supply could all become live, were it not for suplemental bonding like gas and water pipes if it were to lose neutral.

 

[Andy™]

Those are both cases for not relying ONLY on TNCS for earthing.Also very valid points for things like caravans that are made of metal.

But I don't see why exporting a tncs is any worse than any tncs installation in the first place. A house with a tncs supply could all become live, were it not for suplemental bonding like gas and water pipes if it were to lose neutral.

your missing a vital part here. in a house, everything will be at 230v (or whatever it is). therefore you shouldnt get a shock since everything is the same. export it, expecially to anything or metallic construction, and everything inside will be at same voltage, but there will be a voltage between anything metallic on the building and the ground the person is standing on.

similar thing with outside taps - there may be a volt difference between that and the ground.

and your quote - 'A house with a tncs supply could all become live, were it not for suplemental bonding like gas and water pipes if it were to lose neutral.' is not true. yes, everything will become live. but it will all be at the same voltage. supp bonding etc doesnt immediately remove any possible voltage. it will usually help keep the voltage down though, but lost neutral before RCD means RCD wont trip

 

[kme]

Those are both cases for not relying ONLY on TNCS for earthing.Also very valid points for things like caravans that are made of metal.

But I don't see why exporting a tncs is any worse than any tncs installation in the first place. A house with a tncs supply could all become live, were it not for suplemental bonding like gas and water pipes if it were to lose neutral.

WHAT??

C`mon peeps, brains in gear here.

As Andy has just pointed out, that won`t help. Besides which gas & water pipes aren`t "supplemental".

If you don`t see why it`s any worse to export it, do as has already been suggested, and re-read the "exported earth" threads - there`s a lot of info in there, which may give you a better understanding.

KME