i have never had a problem with crimping on to an existing ground in that fashion. The only issue i have had in that regard is where the existing ground was quite old, and was split bolted on to the ground wire going out to the ground rods. the inspector had me change it to a crimp so that the new transformer is properly grounded.

 

That is actually a great question. If you did as you said, you would be at ground potential, but would it be to "CODE"? Are you comprising the path for the aberrant current?

 

It is very common in most industrial and a good number of commercial applications to have a common bonding conductor either around the exterior of the building or underground and connected to the structure of the building.

Among other things, it allows for the attachment of secondary transformers to be bonded to the system ground without the need to "home run" the bonding conductor to the system ground.

Many installations have a cad weld right to the structure or a crimp connection to the bonding conductor. Split bolts / mechanical connections are not approved.

The only limitation to all of this is as you suggest is the size of the conductor. Most I have seen are 1/0. That is plenty for 90% of applications. If you are installing a transformer that needs more then that, it is likely it's own service and you may only need to bond to the structure and not connect to a separate system ground.

What you want to avoid is the situation where you have two separate system grounds with potential in between them...potentially dangerous unless they are fully isolated from each other.

Cheers

John

 

Take a look at 250.64

Edit -

Electrically feasible yes, safe yes, the law?

Never mind...I see your Canadian CEC for you, not NEC. They should have a book that cross references the two code books.