Wiring Stables

csm86 · Oct 23, 2013

Hi, first time poster. I have been asked to wire a new build stable and was looking for advice on the earthing arrangements. Scottish power recently brought a PME supply to an external building, I then ran a 4 core SWA with a separate earth into the stables. However I have since found out that it is meant to be a TT system, is this correct? The stables construction is a concrete base with steel beams and between the beams are prefabricated concrete slabs at around 2 meters in height (if that makes sense). Does this type of structure still need to be TT'd? One last question (sorry for being long winded) the ground it is on is very rocky below the surface what would be the best way to drive earth rods into this if needed? Thanks for any advice.

Richard Burns · Oct 23, 2013

It is generally not recommended to use TNCS earthing for areas where livestock are present.
The construction of the building is not relevant it is the risk to the livestock that is at issue.
There are also a lot of supplementary bonding requirements to prevent uncomfortable PD differences for livestock.
The steel beams would also need bonding.

Rocky substrates are not good for TT systems, if you mean there are a lot of rocks then drilling a hole with an SDS drill beforehand makes it easier to get rods in.
If you mean that whole surface is solid rock then you will have problems getting a good earth and tape or strip over a large area may be a better solution.

It would be a good idea to read section 705 of BS7671 to be aware of the requirements.

telectrix · Oct 23, 2013

might get shot down in flames here, but anyway. use the PME, drive in a couple of rods as well. make sure all circuits are RCD protected, and that cables that are in reach of horses are enclosed in steel conduit.

7029 dave · Oct 23, 2013

Richard has given you a good overview of the earthing arrangements. ref to 705

Farmelectrics · Oct 23, 2013

Tel can you combine a pme system with a tt sure you can but why

Guest55 · Oct 23, 2013

farmelectrics said:
Tel can you combine a pme system with a tt sure you can but why

course you can , earth rods at both the source and end of line can act as a failsafe if the dno combined E /N breaks down.
but ultimately your relying on a rcd to bail you out in these conditions.
speaking of which i'd recommend 10mA devices for areas containing horses , the human heart may be able to take 30ma , but most animals cant.