Joined
·
77 Posts
Working on the grounding and bonding for a large commercial / warehouse building with multiple services. I'll try to describe as briefly as I can.
500Kva, 277.480V pad mount transformer feeds:
(1) Existing 400A meter: GEC from meter to rod #1, interior service trough (used as LB) not bonded (fed with pvc), grounding conductor with service conductors bonded at both meter and panelboard (service disco).
(1) Existing 100A meter: GEC from meter to rod, interior service trough (used as LB) not bonded (fed with pvc), grounding conductor with service conductors bonded at both meter and panelboard (service disco).
(1) Existing 200A meter: (fire pump) GEC from meter to rod #2.
(2) New 600A CT cabinets
We installed the 600A services. I have installed a 2/0 Cu bond in the CT cab from the cabinet to the grounded circuit conductor. The 600A MB panelboards have a 3/0 Cu main bonding jumper.
I have installed a common grounding busbar on the wall. To it I have:
(1) 2/0 Cu GEC from each 600A panelboard
(1) #6 Cu GEC from the 100A meter that I have also bonded to its trough with a feed through lug. I will remove the parallel ground between meter and panelboard.
(1) 3/0 Al GEC from the 400A meter that I have also bonded to its trough with a feed through lug. I will remove the parallel ground between meter and panelboard.
(1) #6 Cu GEC from a 45Kva SDS that currently goes to rod #2.
(1) 3/0 Cu GEC up to building steel
From building steel in another room (1) 3/0 Cu Common GEC down to 4" steel water main.
From another 45Kva SDS 800' away a #6 Cu GEC to building steel.
The 200A fire pump service will get bonded to the water main at the same location as the common GEC but will not have a GEC connecting directly to the common grounding bus.
My questions are about the ground rod connections. Should I leave the existing rod connections? There are two rods and there is not a bonding jumper between them. One serves the 200A service and the other serves the 400A and 100A. Because the common GEC is using the water main as an electrode can the connections to these supplemental rods be made anywhere without connecting them together?
If I leave the existing rod connections I will install a GEC from each of the 600A CT's to rod #1.
The other option would be to disconnect all the existing GEC's to rods and install (1) GEC from the common grounding bus to a single rod making sure all services are bonded to the common grounding bar sized per 250.66.
That was not brief. Sorry. If anyone is still reading.
What do you think?
500Kva, 277.480V pad mount transformer feeds:
(1) Existing 400A meter: GEC from meter to rod #1, interior service trough (used as LB) not bonded (fed with pvc), grounding conductor with service conductors bonded at both meter and panelboard (service disco).
(1) Existing 100A meter: GEC from meter to rod, interior service trough (used as LB) not bonded (fed with pvc), grounding conductor with service conductors bonded at both meter and panelboard (service disco).
(1) Existing 200A meter: (fire pump) GEC from meter to rod #2.
(2) New 600A CT cabinets
We installed the 600A services. I have installed a 2/0 Cu bond in the CT cab from the cabinet to the grounded circuit conductor. The 600A MB panelboards have a 3/0 Cu main bonding jumper.
I have installed a common grounding busbar on the wall. To it I have:
(1) 2/0 Cu GEC from each 600A panelboard
(1) #6 Cu GEC from the 100A meter that I have also bonded to its trough with a feed through lug. I will remove the parallel ground between meter and panelboard.
(1) 3/0 Al GEC from the 400A meter that I have also bonded to its trough with a feed through lug. I will remove the parallel ground between meter and panelboard.
(1) #6 Cu GEC from a 45Kva SDS that currently goes to rod #2.
(1) 3/0 Cu GEC up to building steel
From building steel in another room (1) 3/0 Cu Common GEC down to 4" steel water main.
From another 45Kva SDS 800' away a #6 Cu GEC to building steel.
The 200A fire pump service will get bonded to the water main at the same location as the common GEC but will not have a GEC connecting directly to the common grounding bus.
My questions are about the ground rod connections. Should I leave the existing rod connections? There are two rods and there is not a bonding jumper between them. One serves the 200A service and the other serves the 400A and 100A. Because the common GEC is using the water main as an electrode can the connections to these supplemental rods be made anywhere without connecting them together?
If I leave the existing rod connections I will install a GEC from each of the 600A CT's to rod #1.
The other option would be to disconnect all the existing GEC's to rods and install (1) GEC from the common grounding bus to a single rod making sure all services are bonded to the common grounding bar sized per 250.66.
That was not brief. Sorry. If anyone is still reading.
What do you think?
