Caravan Site Supply

[ukants]

Hello folks. Sorry for the quality of the picture but looking at it I can't decide if this supply is TT or TNS. It's definately not TNCS (which is good as it's a static caravan site). As you can see, there's what appears to be an earth rod going into the ground which is also connected to the bracket that's clamped onto the lead sheath of the incomer. So what earthing arrangement is it?

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• ukants
• 10 Sep 2008
• 1

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[Spark123]

It ain't TT if it is connected directly back to the distribution transformer via a metal conductor. If it is TT then it should only be protecting RCD protected circuits as a fault on the incoming side may not clear the fuse back at the sub causing voltage to become apparent on ecps.
What sort of Ze reading do you get?

 

[Lectrician]

If you have a connection to the sheath, ten regardless of if there is an earth rod or not, you have a TN-S system.

You obviously need to do an EFL Imp test to ensure the earth is satisfactory. A visual glance is not acceptable.

 

[ukants]

Thanks for your replies.
No tests have been done yet as I just had a quick glance at it today.
Would it be unusual or indeed unacceptable to have rods on a TNS system?

 

[Spark123]

Don't think it is unacceptable, maybe not necessary.