Static Caravan Installation

[ukants]

Worked on a static caravan site for the first time today and not sure about some of the installation methods used. The TNCS supply to the outdoor joint boxes seems fine: 16.0mm SWA into the meter and henley block, then through a 80A mcb and a 30mA rcd. The things that I question are the cable from this joint box to the CU inside the home is 16.0mm T&E, thus making the main earth only 6.00mm. The set up inside is ok with 10.0mm eq.bond. but there is another 30mA rcd as the main switch for the CU.
In my mind, the CU 30mA rcd is correct inside, with perhaps a 150mA (delayed?) rcd in the outside joint box protecting the cable, if needed. As it is, there is no discrimnation between the two and they both trip alternately during the rcd tests. Also, the 16.0mm t&e should be 16.0 SWA, for both underground protection and a 16.0mm main earth. Or am I wrong to term this the main earth? Would that be just be the earth from the supply to the CU back at the point which feeds the whole site?

Cheers,

Ants

 

[Spark123]

Isn't TNCS banned for caravans in the ESQCR?

 

[securespark]

I thought so, too.

 

[plugwash]

If the supply to the outside joint boxes is TN-C-S rather than TN-S then you should not be using the earth from it for the caravan. You should be using an earth rod.

Also if it is a hard wired hookup I would agree that putting a 30ma RCD in it is stupid.

And yes if it is burried T&E is completely inappropriate, T&E is far from ideal for outside runs anyway.

All in all this hookup seems like a complete bodge.

 

[ukants]

Isn't TNCS banned for caravans in the ESQCR?

Yes, sorry my mistake. I believe the caravan supply is TT'd from the main dis board. I'm not actually on the job yet, was just taking a look as I may well be soon and wanted to familiarise myself with the set up. The other info is very useful, thanks.

Regards,

Ants