Grounding Requirements for seperate structure

[KWH]

I am going to feed a seperate structure from a panel 120/240 single phase and understand you need a fourth wire for the ground, concerning the ground rod at the new structure do you need one ground rod or two. ( there is no ufer, plumbing or steel )

 

[texie]

I am going to feed a seperate structure from a panel 120/240 single phase and understand you need a fourth wire for the ground, concerning the ground rod at the new structure do you need one ground rod or two. ( there is no ufer, plumbing or steel )

2 ground rods and don't bond the neutral at the out building disconnect.

 

[kwired]

If you can prove the first rod has a resistance of 25 ohms or less you don't need the second one. Most people don't want to spend the $$ to have equipment that tests this or take the time to do it via alternate methods and therefore drive second rod and don't worry about what the resistance is. This is in 250.53(A)(2) - the exception afterward is where the 25 ohm or less portion is mentioned.

 

[tom baker]

At the separate building, you need a grounding electrode system per 250.52. It can be driven electrodes, concrete encased electrode, any or all.