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Does not really matter but it's got me scratching my head wondering why.
A friend has a collection of cabins which is his home in a wood and the mains supply arrives at a near disused cabin where the meters are and with a Henley block it is divided into the local supply and a supply to a 100A switched fuse box and from there to next cabin down the hill.
He was going to use the cabin with the meter in it for visitors and asked me to change some of the old 15A sockets for 13A.
At which point I spotted the ELCB-v and set about some further tests.
Returning armed with RCD and Earth Loop Tester it was found there was an extremely high reading in all cabins around the 350 ohm mark but the RCD did work in the inhabited cabins.
So sent him to get earth rod, consumer unit etc. Starting at the cabin with meter I fitted new consumer unit and knocked in a new earth rod. Got a reading of 35 ohms so left it at that.
Now moved to lived in cabin and this is the strange bit. Earth loop impedance dropped to 12 ohms. How? I was going to fit a second earth rod but clearly not really needed but how do I get a lower reading at furthest point from earth rod?
As I said to start with it passes and the RCD's all trip within the time and at 30ma so all OK but can't work out why lower reading in furthest cabin from incoming mains?
As I write this I have just one thought I wonder where the boards earth rod is? The 11kV lines are closer to cabin with low reading than cabin where mains enters.
Any ideas?
A friend has a collection of cabins which is his home in a wood and the mains supply arrives at a near disused cabin where the meters are and with a Henley block it is divided into the local supply and a supply to a 100A switched fuse box and from there to next cabin down the hill.
He was going to use the cabin with the meter in it for visitors and asked me to change some of the old 15A sockets for 13A.
At which point I spotted the ELCB-v and set about some further tests.
Returning armed with RCD and Earth Loop Tester it was found there was an extremely high reading in all cabins around the 350 ohm mark but the RCD did work in the inhabited cabins.
So sent him to get earth rod, consumer unit etc. Starting at the cabin with meter I fitted new consumer unit and knocked in a new earth rod. Got a reading of 35 ohms so left it at that.
Now moved to lived in cabin and this is the strange bit. Earth loop impedance dropped to 12 ohms. How? I was going to fit a second earth rod but clearly not really needed but how do I get a lower reading at furthest point from earth rod?
As I said to start with it passes and the RCD's all trip within the time and at 30ma so all OK but can't work out why lower reading in furthest cabin from incoming mains?
As I write this I have just one thought I wonder where the boards earth rod is? The 11kV lines are closer to cabin with low reading than cabin where mains enters.
Any ideas?