earth electrode testing

[snowplough]

Cheers nickblake,

I have actually seen this diagram with the 10 x the rod length, current and potential rod etc, im just trying understand if the ground around the rod is of pretty low resistance , what good would that be if the rest of it leading upto say the suppliers earth tansformers rod is of high resistanc, hence high reading i think.

Many Thanks

Locket

 

[Deleted member 26818]

There will very likely be other earth paths available between the installation electrode and the TX electrode.
The majority of TXs provide various earthing systems. TT is usually used for installations which are so distant that the cost is prohibitive to supply either TN-S or TN-C-S.
Other installations supplied by the same TX may well be on TN-S or TN-C-S, and if any of them are between the TT installation and the TX, their earth paths will be utilised.
On a new installation, you would test the electrode to ensure that you have a sound and reliable electrode/soil interface.
Then upon connection to the supply, you would test the Ze to ensure that the earth fault path is within limits. If it isn't, then you would consider your alternatives, such as extending the depth of a rod, or the installation of supplementary rods.
Remember that although it is recommended that the earth electrode resistance should be below 200Ω for stabillity and reliability, the Zs of the final circuits in the installation can be up to 1667Ω.

 

[snowplough]

Many Thanks Spinlondon, i will have aread of what you put and try and get my head around it.

Regards

Locket

 

[somersetsparks]

Yep, earth currents can go into the ground and then up next doors gas pipe and cause there faithful old elcb trip!