Outdoor Industrial Substation Grounding

[JBD]

I am evaluating the grounding for an outdoor switch yard (open air 35KV structure and metal-enclosed 5KV gear). What do I need to consider for the bonding of the chain-link (cyclone) fence. I know to bond each side of each gate (or jumper across the opening). Does every support post need to be bonded or do the cross members provide enough continuity? I can't belive a single location bond to the ground grid is adequate.

 

[cuky2000]

First of all as general rule both sides of the fence must be within the maximum allowable touch and step potential including gates and personnel access doors.

To achieve the above goal, The National Electric Safety Code (ANSI/IEEE Std C2), IEEE Std 80 and other grounding safety practices recommend the following:
[blue]1- Provide a perimeter ring buried cable 3 ft beyond the fence connected to the main internal ground grid and the fence.
2- Connect gateposts and extend the outer grid to include gates and doors if outward swing.
3- Connect all corner post and line post every 40 to 50 feet.[/blue]
If require, ground grid could be improved by ground wells, chemical ground, Uffer ground, counterpoise cable and other techniques. Surface layer with crushed rock and other similar materials should be considered around the fence.

 

[alehman]

The RUS Sustation Design Guide is a good reference. See section 9.10.10.

http://www.usda.gov/rus/electric/pubs/1724e300/1724e300.pdf

There is much more to safe grounding than just installing a conductor and bonding the fence. You may wish to hire an expert if you are not experienced in this area.