Why ground rods, if grounded at house panel?

[chopperimpala]

Been a "lurker" here for a while and I searched BEFORE I posted and may have not put in the right terminalogy so I didn't get an answer.
So,... My question is: If power is sourced from the house to a shop/garage say with a HOT, HOT, NEUTRAL, and GROUND. When going into the shop breaker box, why do you put a grounding rod in at the shop too? Also does that mean you have the ground from the house attached to the ground strap in the shop box and also "daisy chained" to the ground bar in the ground at the shop???
Thanks, Ken

 

[MrMark]

Two reasons off the top of my head: lightning protection at the detached structure and to stablize the neutral voltage at around 0V at that structure. There may be another reason I forget. The main two are the ones I listed.

 

[chopperimpala]

Thanks, that makes sense. So when hooking up the in-ground rod, do you just add another ground wire from the ground strip in the box, out to it?? Meaning ground from the house to the ground strip in shop, then from the ground strip in the shop out to the in-ground rod.
Thanks again, Ken

 

[egdede]

My question is: If power is sourced from the house to a shop/garage say with a HOT, HOT, NEUTRAL, and GROUND. When going into the shop breaker box, why do you put a grounding rod in at the shop too?

In my neighborhood, it comes in w/2 hots and a neutral. This is another reason for stringent grounding requirements.

 

[MrMark]

Thanks, that makes sense. So when hooking up the in-ground rod, do you just add another ground wire from the ground strip in the box, out to it?? Meaning ground from the house to the ground strip in shop, then from the ground strip in the shop out to the in-ground rod.
Thanks again, Ken

Yes. The ground wire from the buss bar in the panel must also bond metalic water pipe if present. That should be one continuous wire, it should pass through the clamp on the rod and continue to the clamp on the water pipe.

 

[MrMark]

Let me amend on my original post. The reason for the rod at the remote structure must be just lightning and maybe static discharge. The neutral is not tied to the ground buss bar at this point. The neutral is only tied to the ground bar and the ground rod at the entrance. This is the point where the ground rod would reference the neutral to Earth potential, not the detached building with the second rod.