TTing a shed

[amckay]

Bit of advice please. I've run a 4mm t+e supply to my mums shed (4m x 2m). The shed is 3m away from the DB in the house. Supply is tncs (not sure if its been pme'd at any point, ex council house).
Now I recon I need to rod it rather than export the earth, because if the supply neutral fails and a fault occurs it will bring the real earth in the garden to 230v. (I think that's right, I don't do any theory in my job so might need a sharp reminder!)
I have never seen an earth rod before let alone installed one. I'll buy GN8 and follow that guidance, but how do you drive them into the ground? I can't expect a lump hammer would be up to the job without bending the rods!

 

[amckay]

Forgot to mention, there are two 58w 5ft fluorescent tubes and 4 double socket outlets.

Fed from a 32a rcbo 30ma in house and a garage CU with 6a MCB on lighting and 16A MCB on ring.

 

[Leesparkykent]

Is the shed made of wood?

 

[amckay]

Oh sorry yes its all wood on a concrete base

 

[Leesparkykent]

Oh sorry yes its all wood on a concrete base

Any extraneous conductive parts within shed?

 

[amckay]

Oh sorry yes its all wood on a concrete base

Any extraneous conductive parts within shed?

No mate. The frame is timber and the walls are all marine grade ply about 25mm thick. The roof is also a timber frame with ply and covered in felt.
Nothing metal within, except for bolts holding the frame into the concrete but only the tip of the head is exposed as they're countersunk.
Some kitchen fittings will be going in for tidy storage but all wooden cupboards. No water or gas supply will be going in.

 

[amckay]

They may wish to install a light on the outside. A bit like a victorian style lantern next to front doors (bad description but you find them in b+q for £15 with a pir) which will be going next to the door around shoulder/head height.

 

[Leesparkykent]

Then the shed is fine with the TN-C-S earthing arrangement as it is. If there was extraneous conductive parts within/entering the shed then you could still use the TN-C-S earth but you would also have to install a suitably sized bond.

 

[Robson689]

In regards to driving the rods we normally start with a sledgehammer (easier to feel if you're hitting any pipes or anything) then carry on with an electric breaker once the first rod is all the way down.

 

[Leesparkykent]

http://electrical.------.org/wiring-matters/45/pme.cfm?type=pdf this is also worth a read regarding your understanding on the supply neutral being lost.

 

[amckay]

Thanks for your input, its really appreciated

 

[Richard Burns]

An SDS drill on hammer only can also help drive the rod if you do not fancy the sledge hammer, but you would need an adapter to connect tot he rod., I made one from a broken SDS bit and a socket and use the nut to drive the rod.