Ground Rods

[Houston]

I always thought code said you need to ground rods. Where does it say you have to have 2 to count as a grounding electrode. The only kinda referance i found was 250.56. I always drive a second ground rod when I do a panel change, but I dont think its required. unless 25 ohms or less.

 

[augie47]

You really need to review Art 250 Part III on the grounding elctrode system.
That section of the Code defines the variosu grounding electrodes for you and tell which ones need supplemental electrodes, etc.

 

[mistermudd]

Can you prove to the inspector that the one ground rod has a resistance of 25 ohms or less? Probably much easier just to drive the second rod and call it good.

 

[infinity]

You do not need to install ground rods. You do need to install a grounding electrode system which can consist of many different electrodes with ground rods being one of them. If you had a CEE in the footing you would never need to install a ground rod. As Houston said you need to ensure that when using only one rod that it has a resistance of 25 ohms or less. In practical terms, it's easier to just install two rods and you've met the requirement.