Discuss High ZE Reading in Flat in the UK Electrical Forum area at ElectriciansForums.net

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I have been asked to carry out a rewire of a top floor flat when checking the existing supply characteristics.
TN-S with a ZE of 1.24 ohms and PFC of 1.91 KA. 1361 Type 2 with 100 amp Fuse

Should I contact the DNO and ask for them to come and check before commencing work.
Unable to treat as TT and run earth cable down the back of the building, will be using a Wylex dual RCD board for all circuits.
If I complete a certificate all my Zs reading will be really high.
 
Yes that ze is far too high, should be about 0.8 for a tns system. Contact dno and ask if a tncs upgrade is available, otherwise no choice but to convert to tt.
Could be that the dno have not provided an earth for that installation.
 
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Think you NEED to answer Jeremy's question first, BEFORE you go calling the DNO!!!


Is the origin of the supply in the flat or in a communal meter cupboard downstairs?

The way i'm reading your OP, is that your taking your Ze test readings from the flat's CU which isn't Ze at all, but Zs, and you should be leaving all earthing and bonding conductors in place for a true Zs reading. Taking Zs at the sub-main CU, is commonly called Zdb...
 
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contatced DNO they are comming out on Wednesday this week to check all the flats are due for an upgrade.
See what they say let you know thanks for all input.
 
Just a POINT with the Ze. Looks like you're getting the right figures, not necessarily in the right order.
 
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