Bonding & grounding at main disconnect and remote gutter

[george969]

We have a 1200A 3p 4w 208V service supplied with 3 sets of 600MCM copper. The weatherheads and conduits are threaded rigid conduit. The run is less than 25' to main disconnect. The service GEC is 3/0 copper connected to 3 rods and a water pipe -- no building steel. The GEC is terminated in the 1200A fused main disconnect & bonded to the neutral.

We leave the main disconnect with 4 each 3.5" PVC parallel conduits. Each conduit has 4ea 500MCM Al plus a 3/0AL EGC. This is supplying a remote steel trough for future disconnects by the tenant's contractor. The 3/0 AL EGC's are bonded to the trough at an terminal block. The grounds originate at a terminal block in the main disconnect where the EGC is also bonded and terminated.

Is there any additional grounding or bonding needed at the trough? We have the neutral and ground separate at the trough.

Is 3/0 AL the correct size?

We were told that we are missing some grounds and bonding at the trough and EGC sizes is not correct?

We have each set of phase conductors terminated with ILSCO terminal blocks.

Not sure what is wrong?

 

[augie47]

With a 1200 amp OCP using an AL conductor for your EGC I believe it should be a 250 kcmil per 250.122.
How is bonding of the service equipment handled ?. If you are doing that with a conductor (as opposed to a factory "strap") it would need to be a 225 kcmil based on (3) 600 service conductors.

 

[george969]

With a 1200 amp OCP using an AL conductor for your EGC I believe it should be a 250 kcmil per 250.122.
How is bonding of the service equipment handled ?. If you are doing that with a conductor (as opposed to a factory "strap") it would need to be a 225 kcmil based on (3) 600 service conductors.

The main entrance conductors are 600MCM copper and the GEC is 3/0 copper. Bonding is per factory strap. This is all correct.

The parallel feeders from 1200A disconnect to trough are 500MCM AL and the EGC was to be 3/0AL so we need to change to 250AL per table 250.122.

We used table 250.66 not 250.122 for the EGC...this is NOT cut or pulled yet so an easy fix.

THANKS