Site Temps earthing question

[Alan Marriott]

Hi
Currently on a job at a hospital where we are installing temporary site supplies to canteen toilet block and office.
The supply is Tncs from hospital but the hospital electrician and contractor doesn’t want us to install earth rods in case of services below ground and they’re not prepared to scan ground.
Hospital electrician says we can use PME supply as long as it’s on RCD but surely this isn’t correct as if a broken PEN conductor will make all cabins live potentially and rcd won’t pick this up?
Also what other option do we have if can’t use pme and they don’t want TT. Surely under regs it has to be TT and there’s no arguing?

Thanks

 

[westward10]

They will be fine on TN-C-S.

 

[newfutile]

You could alway fit a Matt e or similar pen fault device

 

[buzzlightyear]

potentially and rcd won’t pick this up?
Also what other option do we have if can’t use pme and they don’t want TT. Surely under regs it has to be TT and there’s no arguing?

I agree with the site spark, banging a earth rod in a ground would you take responsibility for it with all the pipe work around the hospital.

 

[davesparks]

Are you sure it's TNCS? I'd have thought that's unusual for a hospital, they normally have pretty big supplies if not 11kV incoming which would all be TNS.

But either way it will have earth rods for the backup generatir, a lightning protection system and other bonded metalwork buried in the ground. All this will add up to quite a nice earth electrode to keep things safe if a PEN fault occurs.