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I think these overhead earthing systems are being done away with due to copper theives leaving the rural customer without an earth


Not a chance in hell, the cost of taking most of these overhead supplies underground will cost more money than what the banks lost, when the massive fraud scam came to light!! lol!!
 
I was under the impression that we were to assume a value of 16ka(but I could be wrong)
According to the OSG the maximum fault current likely to be found in domestic properties in the UK (unless in heavily built up areas) is 16kA.

However this is probably stated because annex Za of BS60439 provides an additional test, for domestic consumer units that are protected by a BS1361 fuse at the supply, to ensure that a BS60439 consumer unit can take a 16kA fault current without danger.
This permits the use of protective devices in the consumer unit that may not have the short circuit rating to cope with the prospective fault current since the assembly as a whole will cope.
This is part of why the manufactures do not permit different makes of breaker in their consumer units, they say they are not tested for those units.
 
Here's our overhead supply for comparison and comment. Our transformer is served by two high voltage conductors, which in turn come from a string of poles carrying three conductors - ie two of the three branch off to our property. I assumed these were two phases from three phase, but comments here now make me unsure.

Earthing Arrangements Explained + Photo's {filename} | ElectriciansForums.net


One green/yellow sheathed cable comes from the case of the transformer into the ground on the N side of the pole.

Earthing Arrangements Explained + Photo's {filename} | ElectriciansForums.net


On the other side of the pole the two cables out of the transformer join the underground service cable which goes to our meter cabinet. One connects via the isolator or fuse or whatever it is (the grey item), the other is clamped directly. After the join to the service cable, there's another earth that goes underground at the foot of the pole on the S side. The DNO guy who traced and marked the cable routes for us said that this would run some distance horizontally underground while still insulated, then further distance uninsulated.

Earthing Arrangements Explained + Photo's {filename} | ElectriciansForums.net


Our earthing arrangement was described as "CEW" and also "TN-S" by the DNO engineer, after he opened part of the cut-out to check.

Tony S
 
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So does anyone have a picture of a PME system :joker: Seeing as freshman are bound to be seeing that old chestnut.
I know, I know, but the question will be asked, guaranteed.
 
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