Plant/facility ground grid
- Thread starter pamdeng
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
What do you mean by a facility ground grid? Anything other than what is required by Article 250 is a design issue and not a code issue. You can do whatever you want to.
a brief answer
a brief answer
The current project I'm doing has a ground grid of 80 3/4" x 10" cu. ground rods encircling the perimeter of the building exothermically connected to a cross-hatch [checkerboard] of 4/0 bare cu. spaced on 20' centers exothermically connected. Tails of 4/0 were turned up at columns.
This was installed after the mass excavation. Before slabs were poured the tails were installed to building steel, the connections were made to the metal pipe systems and a tail for cu. equipment busbars in each room were turned up at each location.
There is a seperate lightning protection system.
Design criteria varies from mission critical installations to nec requirements, though, as oftened reminded, the nec is the minimum requirement.
a brief answer
The current project I'm doing has a ground grid of 80 3/4" x 10" cu. ground rods encircling the perimeter of the building exothermically connected to a cross-hatch [checkerboard] of 4/0 bare cu. spaced on 20' centers exothermically connected. Tails of 4/0 were turned up at columns.
This was installed after the mass excavation. Before slabs were poured the tails were installed to building steel, the connections were made to the metal pipe systems and a tail for cu. equipment busbars in each room were turned up at each location.
There is a seperate lightning protection system.
Design criteria varies from mission critical installations to nec requirements, though, as oftened reminded, the nec is the minimum requirement.
It depends on the grounding requirements of the initial phase. If there is a requirement for a particular ground resistance, then the complete facility ground grid may be required to achieve this resistance. If the available grid fault current during the initial phase is high enough to cause touch voltage problems on a partial grid, then the complete grid may be required initially. If the lightning protection grounding system is required initially, it may not be effective if only a portion of the grid is installed initially.pamdeng said:
in my haste typing...
in my haste typing...
There is a reason I have someone else vet my typing, I misspoke, the lightening protection system is tied to the ground grid.
This is a 45 megawatt data center, about 400,00 sq.ft. building, soil composition plays a large role in design of ground grids here.
in my haste typing...
There is a reason I have someone else vet my typing, I misspoke, the lightening protection system is tied to the ground grid.
This is a 45 megawatt data center, about 400,00 sq.ft. building, soil composition plays a large role in design of ground grids here.
- Status