well casing as a grounding means

[wireman1]

article 250.50 states all grounding electrodes described in 250.52 (a) (1) through (a) (6) that are present ateach bldg shall be used to form the grounding system. if not available than one or more of the electrodes specified in 250 52 (a) (4) through (a) (8) shall be used . my ques. is a bldg. 400 by 400 is being built for manuf and storage in this case 250 52 (a) (3) is present at the site . the service is 1600 amp 3 phase 208/ 120 .is grounding to the rebar which is longer than 30 feet and incased in concrete with a nunber 4 bare copper wire the only requirment to satisify the code requirment. 2nd ques there will be no water line going to the bldg but 75 feet away there ia a well which services other bldgs the casing for the well is steel and goes down at least 100 ft .this to me is a lot better grounding means then that piece of rebar.and should be used.if they were to use the well would they have to use 3/0wire and cad weld it to the well casing.as the service is 1600 amps. yet you only need a number 4 to the rebar

 

[kwired]

If you want to use it I see nothing to stop you. I also do not see it as required since it is 75 feet away it is a separate structure itself.

Are you sure the casing is steel and not just the top section? Most wells around here are all plastic casing if newer than 25-30 years or so with just the very top being metal for withstanding physical abuse.

 

[renosteinke]

I'm not clear on what you're trying to do.

The well casing is nothing but a pipe. For a 'made electrode,' we're not required to use more than a #6 wire for the purposes of "grounding" the service - no matter how large the service is. The casing is no different than a ground rod in this regard.

No matter the distance away, though, you'll still need to run a ground wire with your power feed to clear faults.

As with a water line supplying a house, you've now place the well casing in an ambiguous position. Assuming you only have a single circuit to feed the pump, there's no need for a 'grounding electrode.' Yet, there is still a need to bond the well casing to the green wire that goes back to the panel. We can't tell if the electricity is flowing out of the wire or into it.