Main Earth question with pics

[Norv]

Went to a job today to disconnect the storage heaters & add a supply for a combi in a property that was huge to say the least. (The ceilings were 4 metres high & then there were 2 staicases to each floor). It had been converted to 3 flats (one on each floor). I was working on the top flat.

The 3 phase supply is on the bottom floor right by the entrance. This is the supply for the storage heaters with the wires coming out the top of the white fuse box going straight to the storage heaters in the flat I was working on.

The red & black tails coming out the jb's just above it was going to this

from here it went straight into a 30ma RCD & then into the CU with a 30ma RCD protecting the sockets.

On my first photo, that 6mm earth wire coming out the white fusebox is going straight to the CU & the other end is going to an earth rod just outside the front door. There is PME available on the landlords supply (bottom flat)

I did a Ze reading at the CU in the flat I was working on & got 275 ohms.

I think I know the answer to the question but have I got to change the 6mm main earth cable to 16mm & could I use a small henly block to split the landlords PME & take it to the top flat ?

This is what I'm up against

 

[Spark123]

I take it the landlords is also from the same cutout?
If so I do not see any real issue with using the same earth for the whole premises.

 

[Norv]

Ah, no its not. He's got his own cutout. The middle flat is using the landlords PME & its on the same supply as the flat I'm working on.

 

[Spark123]

I think you are meant to have the same earth as the cutout, as someone now working on the landlords flat cutout can disconnect the means of earthing to the live middle flat

 

[Norv]

The only availabe PME is the landlords.

I suppose a new 16mm cable would have to be run in up to the CU ? Just wanted to see what others would do. I suppose its all extra work

 

[RF Lighting]

If the other supply has been PME'd then the network is clearly suitable for this sort of supply.

Why not just ask the DNO to PME the cutout in the picture?

 

[Norv]

Yes RF, thats what I'll do. Simple really. Cheers.