I take it you have already experienced a winter period . If so were you warm ?
Looking at your plan you have 2 outside walls with 4 windows. What floor are you on ? What about insulation? Ceiling heights?
There is also BS EN / IEC 61869-2 2013 Edition, January 31, 2013, which covers instrument transformers. Most electrical items we fit have instructions to be carried out by a qualified or Skilled person & most of the time you are fitting to the manufacturer's specification.
Do your CT clamps conform to any international or British Standards & codes to start with.
You would hope that a 'Skilled Person 'which now replaces 'Competent person' as per BS 7671 a person has undertaken adequate training & practical skills, & who is able to perceive risks & avoid hazards...
20 ohms is okay. You are better off with TT at the house as long as you have a time delay Rcd main switch. Perhaps post a picture of the house panel & cable entry.
Are you qualified as your name implies?
Are you sure it is TNCS or PME. I take it is a secondary metered arrangement with the origin connected to the grid.
Why would you? I guess singles are too expensive. Yes, you can get cable lube from Screwfix. I hate it when I see T & E in conduit must have been a struggle.
To be honest I would get the DNO involved to see if they are happy with the fixing of their equipment & their opinion on the earth clamp. An initial visit by an Electrician to carry out a few safety Tests, knowing he will recommend a Rewire if he knows about what you have already posted. He can...
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