Export pme to portakabin

[Mr Mark Sparks]

Hi
factory unit with 800 amp supply 95 mm main earth and 50 mm main bonds
portakabin has been delivered as a permanent addition
wired on 10 mm 3 core swa and 32 a commando plugs
there is a water supply and metal parts.

am I right in saying that it will need to be put on a stake as the main earth and bonds are so big.

Thanks mark

 

[malcolmsanford]

Sorry Mark not following your logic here mate, why would the size of your main earth and bonds forbid the use of exporting the TNC-S system

 

[Mr Mark Sparks]

hi mal
i had heard/read/dreamt!! that if you were to export pme you had to match main bond size with your earth to the new building

so you belive 10mm 3core is satisfactory in this case?

 

[Billythekid]

Not again . . . . . I see more arguments, and quoting of regulations that have yet to appear in the books I read :90:. It's probably sat on terra-firma anyway.

It's personal choice Mark,

Export PME with bonding conductors, or 'TT' it with RCD etc. Both have pro's, both have con's.

Regards

Billy

 

[malcolmsanford]

Sorry Mark I see where your coming from mate, your saying that your sizing your bonding conductor to the size of the neutral of the supplier, so as your bond is 50mm then the supply neutral must be 150mm+ and table 54.8

In your case though mate your Kabin is not a PME, as your not allowed a PME system inside your installation, so in all intent and purposes you have a PME that at origin as been converted into a TN-S inside the installation

 

[Mr Mark Sparks]

Sorry Mark I see where your coming from mate, your saying that your sizing your bonding conductor to the size of the neutral of the supplier, so as your bond is 50mm then the supply neutral must be 150mm+ and table 54.8

In your case though mate your Kabin is not a PME, as your not allowed a PME system inside your installation, so in all intent and purposes you have a PME that at origin as been converted into a TN-S inside the installation

yep agree with 1st bit

not sure i follow what you mean on 2nd bit please can you clarify thanks

 

[malcolmsanford]

Look at the definition of a PME or TNC-S which is Terra (Earth) Neutral Combined- Separated.

Once beyond the main intake you have just a TN system. The earth and neutral are now separated inside the system, so any further installations inside the complex will be just a TN separated, not a combined

 

[Mr Mark Sparks]

Right I see so nature of supply on installation cert for Kabin would tns not tncs so back to original question can the earth be exported as a 10mm in this case, ( in your opinion)
thanks again

 

[malcolmsanford]

If your going to extend the equipotential zone out to the kabin then any services to this Kabin will have to bond back to the MET via your wiring.

So if your going to use a SWA then you could use a 3 core, the 3rd core will be your bonding conductor and tie this at the Kabin with the SWA at both ends.

 

[Mr Mark Sparks]

And that 3 core doesn't have to be sized to match the incoming neutral and other bonds ?