We visited Vevy in the French part of Switzerland last weekend and while walking from the hotel to the railway station I came across these works for the replacement of an LV distribution cabinet. It doesn't look very Swiss but I guess it is a mixture of new and old. There seems to be several different, separate, earthing tapes. Is this usual?
The number of tapes doesn't matter, the only bit of interest is the area in contact with the soil. However in this case they might just be connecting cable armour etc. to the MET, as they seem rather small and not very deeply buried, so are probably useless as Earth connections! Everything Swiss is not always as tidy as the railway stations and streets! They have many of the same problems as us.
as they seem rather small and not very deeply buried, so are probably useless as Earth connections!
They might be intended more as a buried grid to reduce the potential difference between the box and the ground immediately around it - so more in the vein of bonding rather than earthing.
near surface earth electrode can often be quite effective. I have measured a genset on its skids and got a lower resistance than the rod that was supposed to earth it, and in a hurry, parking the truck on a plate electrode in a puddle is a standard wheeze. The problem is that you are at the mercy of dry weather or ice removing the mobile water molecules, but in the UK at least you do not get freezing at great depths. You do have to think about water tables, and sandy soils can be a problem.
Those tapes could just be corrosion resistant connections to buried rebar etc.
Having two or more ends allows a ring-round test of the connection to the earth electrode at high current rather than just hoping or only testing Zs.
In the first picture there are two connections to lengths of 35(?)mm2 grey sheathed green/yellow cables that appear to go into distribution chamber.
I haven't seen one of these exposed before so I have no idea what is normal. Usually they just open the manhole cover in front to access the cable ducts.
