Loose-fitting earth-rod holes

Question

I have heard whispers of a compound that can be used to backfill, loose-fitting earth-rod holes to impove the connection to earth. Anyone done this? Thanks

GTB · Answer

Hi Allan, 
 Its a compound or dry powder called Bentonite. You can purchase it in bags from most electrical suppliers or even specilist earthing contractors. 
 I have used it on TT earthing systems where we have had to drill bore holes due to ground conditions/geology and fill they hole with Bentonite, try and pack it then drive in the earth rod. 
 Basically it is moisture-retaining clay that is commonly used as a backfill for earth rods installed in drilled holes, or as a layer encapsulating horizontal earth conductors buried in a trench. Its main advantage as far as earthing is concerned is that it has the ability to retain moisture in the immediate vicinity of an earth rod, and hold it there for a considerable period of time. This reduces contact resistance and increases the effective size of earth electrodes. 
 
 Hope that helps, but its easy to purchase and not uncommon. 
 Cheers GTB

Loose-fitting earth-rod holes

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