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baggy61

Evening gents,
Called yesterday to change a broken fcu.On completion checked zs, 115 ohms. Cut out had no earth clamp on lead (pilcsta), but I found 10mm G/Y going into block paving. The lady had a board change in 2010 by scottish & southern With ze given as 6.5 ohms. Did a ze via lead sheath & got o.35. I spoke to s&s who sent someone to look today . They said earths not our responsibility ( I Know) most sparkies would just put a clamp on the lead & say nowt.
Any comments as to why it might have been tt'd in the past, next door tns & 3 ohms and how EFLI can go from 6.5 to 114 ohms in 3years.
Regards.
 
I'd guess the cert for the board change would have the earth down as a TT. If they've not supplied an earth in the past then it's not down to them to provide one now and simply putting a clamp on it doesn't make it so.
I certainly wouldn't "just put a clamp on it and say nowt"
The change could have occurred for any amount of reasons, you say the cable disappears below some block paving. Who's to say that the pavers haven't done something to dislodge the rod or the connection to it.
 
did you check ze with bonding wires disconnected the zs reading you got maybe through bonds as trev says you dont know what is hiding under the paving
 
did you check ze with bonding wires disconnected the zs reading you got maybe through bonds as trev says you dont know what is hiding under the paving
Did,nt check with bonding disconnected as it would have given a higher z.Could n't find water bond, but gas was there.
Put a clamp on & say nowt wasn't my suggestion. It just seems odd to find a tt surrounded by tns but maybe a joint breaking down sometime caused a bad earth & someone tested at the right time & decided to tt it or possibly the jointer forgot to fit the clamp in the first place.
Guess I'll have to dig up paviers.
Thanks for comments gents
 
Correct me if I'm wrong but I'm pretty sure you have to do the Ze test with the main earth disconnected, so you don't get incorrect readings through parallel paths?
 
Is it possible this dry spell we have had has changed the conductivity of surrounding earth. .Was the rod installed during all that rainy weather we have had.
 
well, it's under the patio, and we can't contact the original installer. fred west is dead.
 
Correct me if I'm wrong but I'm pretty sure you have to do the Ze test with the main earth disconnected, so you don't get incorrect readings through parallel paths?
Quite right but as z was surprisingly high not low thats not the issue and as it was a late call & I was just changing fcu I just wanted to check earth cont & op of protective devices
 
Is it possible this dry spell we have had has changed the conductivity of surrounding earth. .Was the rod installed during all that rainy weather we have had.
Dunno, thats why I posted but it seems a big change doesn't it ?.
Just curious as to what others have done in these circumstances. I know it 1553 ohms short of not tripping rcd but I was taught any thing over !00 was to be considered unstable& should be rectified, not by p...ing on rod :teeth_smile:
Regards.
 

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