New caravan site

[eddiecme]

Hi All,

I've got a job to do at new caravan site. The client is paying for 3phase off of the pole that runs through the field and they have built a small solid building at the base. I'm assuming it's going to be connected as PME but i'm yet to confirm.
The client wants supplies to 5 pitches for mobile (drive in) caravans. A little shed type thing for each pitch is going to be installed with a 16A hook up socket and 13A double socket running from a small d/b in each shed. There will also be a 3phase supply to the bore hole pumping station, and single phase supplies to an external pump, electric gate and two further out buildings.
He wants all caravan supplies metered at the main d/b, i've priced a Hager board with internal single phase KW/hr meters, running SWA supplies in the ground to the 5 individual pitches. When two further 16A circuits in each shed for the two individual sockets.
I've never worked on a new caravan site but had a good read of GN7 so just want a few questions answered/opinions on how people would do this with regards to RCD protection and earthing. If it is PME i was thinking running MCBs from the main d/b to supply the sub boards which would have 16A 30mA RCBOs inside, and an earth rod connected to each sub board segregating the PME.
Also opinions on upfront surge protection and options for installing non flammable but still IP rated d/b's in these locations would be appreciated.
Eddie

 

[davesparks]

What on earth has non-flammable DBs got to do with caravan sites?

I would be looking at making the whole site a TT as from your description there doesn't appear to be anything which would benefit from a PME earth. With a bit of consideration you could get a very good Ra on such a site with plenty of rods linked together.

 

[eddiecme]

What on earth has non-flammable DBs got to do with caravan sites?

Absolutely nothing to do with it, ffs its been a long day!


All supplies would then need further RCD protection at source, i guess would be the only implication but you're right i could stand to have a fair few rods in the ground.

 

[davesparks]

Absolutely nothing to do with it, ffs its been a long day!


All supplies would then need further RCD protection at source, i guess would be the only implication but you're right i could stand to have a fair few rods in the ground.

If you get the earthing right you likely won't need additional RCDs at source.

 

[telectrix]

what i've done on similar installs is to use the pme for fault protection of the SWA feeder cables to each pitch, but isolate the earthing at the pitches and TT each pitch.

 

[eddiecme]

what i've done on similar installs is to use the pme for fault protection of the SWA feeder cables to each pitch, but isolate the earthing at the pitches and TT each pitch.

i think this is what i'm probably going to go for. What SPDs have you installed previously?

 

[telectrix]

i've never installed SPDs.

 

[Sparky Ninja]

SPDs? For what part?

I've often installed similar to as telectrix describes.

ESQCR prohibit PME earthing facilities on the pitch socket, so I would distribute PME, isolate the earth (and label it not to be connected) then TT at each point, then something like a 25A/30mA 61009 per pitch. If there is plan for power to the shed for lighting and socket-outlets as well then a little board should suffice.

You could convert to TT and then distribute, but you may have discrimination issues with the RCD and the supply end popping.

It'll be a nice job if the sun is out.