TN-C-S and Special Locations

[RF Lighting]

TN-C-S supplies are a big problem on farms as the CNE conductor can be at a slightly different potential to true earth, and when you've got cows stood on wet ground touching metalwork earthed to the CNE conductor they can feel the difference in voltage.

I know of a farmer who had his milking parlour connected to a TN-C-S supply and his cows would not drop their milk.

 

[viewer]

Do caravan installations connect the structure to neutral similar to the car electrics principle of grounding to zero?

No - should go to earth/ground. A problem with caravans is that sections are often electrically isolated due to expansion/anti vibration separators. They may have straps when built, but these corrode or come loose.

 

[Lectrician]

TN-C-S supplies are a big problem on farms as the CNE conductor can be at a slightly different potential to true earth, and when you've got cows stood on wet ground touching metalwork earthed to the CNE conductor they can feel the difference in voltage.

I know of a farmer who had his milking parlour connected to a TN-C-S supply and his cows would not drop their milk.

Yep, and they literally shlt themself.

Usually all the structural steel in a parlour is continuous welded pieces - including under the concrete - the barriers either side of the walkways are welded together underground and to the concrete reinforcing.

WPD will not provide PME to a farm - not usually a problem as most farms are rural and have their own pole mounted tranny, so TN-S is usually provided as standard. All farms in my area we do any work on are TN-S.

 

[RF Lighting]

I'm just on with a new parlour at the moment. We had to do the welding our selves.

All the reinforcing mesh was welded together and then welded to the toe boards of the main central walkway.

We also sank a rod at one end of each strip of concrete and connected this to the metal work.

The farm we are on has a TN-C-S supply so we are going to TT the new supply for the parlour.

 

[ricicle]

Supplementary bonding, Supplementary bonding, supplementary bonding, supplementary bonding and more supplementary bonding !!

 

[RF Lighting]

oh aye