How best to earth shed on caravan site

[currie123]

Hi

I am going to be running a power supply to a small garden shed on a large caravan site, the shed is owned by the owner of the static caravan to which the shed is beside. Closest power supply is the pitch box, I am running a 6mm swa cable from here to shed( in my Mind pretty straightforward run of 8meters or so).
From memory the pitch supply box has 2 4core16mm cables, two 3 p and n loops from other pitch boxes presumably and the armours are bonded together in the pitch box.
The static caravan is a tt system with an earth rod underneath it which I fully understand. My question is how should I earth the small shed? By way Iof separate rod for the shed or can I do a Ze test at pitch box and if a good reading can u earth by way of the earth of the swa's in pitch box? Unsure of earthing arrangement at the supply distribution board as I have not seen it.
Point to further add it is impractical to run supply from the caravan itself as cable run too far and troublesome, thanks

 

[Jimmy Boy]

Hi

I am going to be running a power supply to a small garden shed on a large caravan site, the shed is owned by the owner of the static caravan to which the shed is beside. Closest power supply is the pitch box, I am running a 6mm swa cable from here to shed( in my Mind pretty straightforward run of 8meters or so).
From memory the pitch supply box has 2 4core16mm cables, two 3 p and n loops from other pitch boxes presumably and the armours are bonded together in the pitch box.
The static caravan is a tt system with an earth rod underneath it which I fully understand. My question is how should I earth the small shed? By way Iof separate rod for the shed or can I do a Ze test at pitch box and if a good reading can u earth by way of the earth of the swa's in pitch box? Unsure of earthing arrangement at the supply distribution board as I have not seen it.
Point to further add it is impractical to run supply from the caravan itself as cable run too far and troublesome, thanks

How will you run the cable ? 708.411.4 does not preclude the use of PME for permanent buildings but a shed isn't is it ?

 

[currie123]

The cable will run under ground. I appreciate pme earthing should not be used on caravan sites,yes it's a shed but would not be regarded as a permanent building.

 

[Jimmy Boy]

Out of interest is the owner permitted to connect a supply to the pitch box other than that which is agreed ? The box is normally owned by the site, not the van owner, I would have thought limitations to supply would have been provided at the box and the van must use up to those limitations, so you feed the shed from the van ?

 

[currie123]

Fair question but they have had the ok from the site owners and there is a meter in the pitch box which I am planning to take my supply from, obviously the 'consumer ' side. The meter is fed from a 32a mcb all inside the pitch box it all looks good to me. What do you think?

 

[Jimmy Boy]

I would quite like to establish the supply characteristics in full is it TNCS in the box ? or TNS

 

[currie123]

Would need to confirm when I go back Steve. It tn-c-s will have to put a rod in and if tn-s I think I can use the existing armours at the pitch box for my earth providing My readings are low enough, would you think that sounds acceptable? Think it's 0.8ohms fit tn-s system

 

[Jimmy Boy]

Would need to confirm when I go back Steve. It tn-c-s will have to put a rod in and if tn-s I think I can use the existing armours at the pitch box for my earth providing My readings are low enough, would you think that sounds acceptable? Think it's 0.8ohms fit tn-s system

Yea let us know I would refer to 708.521.1.1 in the BGB for bury depths and RCD with a 30mA at source the supply cable irrespective of mechanical protection IMHO

 

[currie123]

Ok thanks for advice it is def rcd protected within pitch box by way of 40 rcd and over current protection from 32a mcb. I just need to ascertain earthing arrangement. If I'm unsure il just go with the earth rod although hopefully its tn-s! Cheers again. Stewart

 

[Jimmy Boy]

When you test it Stewart let us know the test results mate it will be interesting to see the Ze on a big site like that and be interested to see the Zs in the shed along with the x1 and x5 on the RCD