Earth pit

[144x]

hi,does anybody know what is the purpose of earth pit in the earthing system of a susbstation? where it should be located?if it is for testing what is the purpose of test and what happens if it is not included in the design? is it for connecting of the shield wire to the substation earth system or connecting an existing earth part to a new one.thanx a lot

 

[7anoter4]

The "Earth pit " of a grounding grid could be a pit above a grounding rod implanted in the Ground. The purpose of this one-
as you already said- is to facilitate connection of a horizontal grounding cable of the Grounding Grid to this vertical rod. It is
also a point used to check the grounding system.

 

[144x]

thanx for the response,but what is going to be checked ,I have seen substations that do not have earth pit,I have seen substations that have their buried mesh coupled to the lightning protection (shield) through disconnecting link in the earth pit.but I do not understand what is the purpose of the disconnecting link.what do they want to check .why should it be disconnected from the shield to test .is it really correct to connect buried mesh to shield wire through this joint box or is it a mistake in design.please check figure 8 in this document for further clarification

http://www.google.com/url?sa=t&rct=...rid&source=web&cd=1&ved=0CE4QFjAA&url=http://

http://www.nationalgrid.com/NR/rdon...n4DoDQ&usg=AFQjCNHCYO1RHOdbxYXxwmYoci9zSUU9cg

all I said is totally contradicted in clauses 7.2.5 and 7.2.6 of this document.and I am unable to find any other reliable source.

 

[bacon4life]

It sounds like the test pit is for when a group of ground rods is driven remotely from the main ground grid. A clamp on tester could then be used to verify the resistance of each group of ground rods.

Example ground grid tester:

http://www.groundtesterstore.com/cr..._-_earth_ground_resistance_training_guide.pdf