dduffee260
Senior Member
- Location
- Texas
I have a service that is 3000 amps. We have a main switchboard with a 3000 amp main circuit breaker. We have to go to the rebar, the building steel, the copper water line and a 3/4" x 10ft ground rod. The rebar is going to be 5/8". The MCB is about 80ft from the copper water line. We have 8 runs of 500 kcmil feeding the MCB.
I am a little lost as to what goes where. Table 250.122 says for a 3000 amp service to use 400 kcmil copper. Do we start at the cold water main coming into the building, then go to the main switchgear, then to the building steel with a continuous run of 400 kcmil copper? Then run from the ground rod with a #6 copper? Do they make an exothermic weld that goes to 5/8" rebar with a 400 kcmil copper? Can we go from the cold water pipe to the rebar, then back from the rebar to the switchgear? I though somewhere it says to use 3/0 copper for equipment ground.
There is a diagram that shows to attach a main bonding jumper from the grounded conductor to the ground bus. Then the connections to the other grounding but there is no size explanation. If I need to explain things different please let me know and I will try. Thanks guys for any help.
I am a little lost as to what goes where. Table 250.122 says for a 3000 amp service to use 400 kcmil copper. Do we start at the cold water main coming into the building, then go to the main switchgear, then to the building steel with a continuous run of 400 kcmil copper? Then run from the ground rod with a #6 copper? Do they make an exothermic weld that goes to 5/8" rebar with a 400 kcmil copper? Can we go from the cold water pipe to the rebar, then back from the rebar to the switchgear? I though somewhere it says to use 3/0 copper for equipment ground.
There is a diagram that shows to attach a main bonding jumper from the grounded conductor to the ground bus. Then the connections to the other grounding but there is no size explanation. If I need to explain things different please let me know and I will try. Thanks guys for any help.