I think this question gets close to answering my question, but I am not quite sure. I have a detached structure, powered by a feeder from the main panel where the ground and neutral are bonded. The ground there goes to a grounding electrode (and also to the water main).
On my detached structure, the ground busbar is connected to the main panel's ground busbar, but not to any other grounding source at the detached structure. If I have a copper water pipe coming in, would it be a bad idea to connect a jumper from it to the ground busbar in my detached structure's subpanel? I think that would be appropriate under NEC 250.52(A)(1) since it runs underground for more than 10'.
Also, if it is a good idea (or required) to bond it to my subpanel ground busbar, does it need to be a dedicated wire going from the bonding strap to the busbar, or can I connect it to the EGC on a nearby receptacle?
EDIT: I think I found that NEC 250.64(C) requires a continuous wire from the grounding strap on the electrode to the busbar in the subpanel, if I am reading it correctly.
Also, it looks like NEC 250.32(B)(1) should settle this question, but in one part it says
An equipment grounding conductor, as described in 250.188 shall be run with the supply conductors and be connected to the building or structure disconnecting means and to the grounding electrode(s).
Any installed neutral
grounded conductorshall not be connected to the equipment grounding conductor or to the grounding electrode(s).
So this just makes it more confusing.