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Posted By Topic: Main earth electrode

Natep
Oct 03 2019 21:49

Hi all, i have been to a job and could not find the earth electrode for the main earth anywhere. However all the earths are bonded together in the switchboard as per usual. The place is 50 years old so I’d think where ever the earth electrode is it will probably need replacing. I’m considering to install a new one but my concern is having 2 main earth rods for the same house, will this cause issues? I’m thinking if there is a potential difference between the 2 earth rods will this cause Nuisance tripping on the RCBOs? I’m not 100% if there even is an existing earth rod as I can’t find it anywhere and there isn’t a earth running down from the board but you would assume it has a main earth somewhere. Any advice is appreciated.

Cheers
   

DougP
Oct 03 2019 22:29

Most older places were earthed to the water pipe. Often up in the ceiling near the hot water header tank.
What work are you doing to the installation? Does it have a separate neutral and earth bar?
As far as "two electrodes" goes, it doesn't matter. It's the same as bonding a slab or water pipe. They are upstream of the RCDs so won't cause them to trip.
If you're doing mains upgrade, you should (almost) always do a new earth stake because firstly the old main earth conductor won't be the right size and the main earth won't be up to current standards.