Fence Grounding

[JWall886]

I have been looking at these standards in the NEC and have tried to look into the NESC (which I know isn't relevant for this situation as it is not a substation) but haven't found a good answer. We're looking at installing a new fence around a station with a CP (Cathodic Protection) system and it is our standard to have the fence be grounded. This particular station is closest ~80 feet to anything besides the incoming and outgoing pipes running under the fence that have the CP system associated with it (much further than the NEC required 16ft for fence grounding). From my understanding it doesn't need to be grounded in this scenario but that is company standards and not a hill I am willing to die on.

All this being said, I can't find anywhere what the maximum distance that is accepted as okay to space grounding rods along the fence. I know about the bonding jumpers length (160 ft) and that the gate posts need to be connected to the grounding system but otherwise I can't find anything anywhere. Our company standard is 20 feet which with the size of our fences, plus the lack of actual need to ground the fence, is frivolous imo but I'm trying to find something to back a number up by instead of picking an arbitrary number for when we look to update the standards.

 

[electrofelon]

Isn't the fence already grounded? Or are the posts mounted on plastic piles of some sort?

 

[Dsg319]

Isn't the fence already grounded? Or are the posts mounted on plastic piles of some sort?

He likely is in a natural gas or oil facility. Where refunding fence grounding/bonding is done.


Most company have their own spec on this.

You likely won’t find anything regarding this in the NEC to satisfy a gas company standard for fence grounding/bonding.

I believe the NEC only hits on likely to become energized and fencing around overhead conductors/substation work.

Correct me if I’m wrong

Maybe try IEEE green book

 

[Fred B]

I know the fence around a cell tower has to be bonded.

Likely the company came up with the 20ft number basis to maintain a consistent gradient along the perimeter of the fence given your typical soil conditions.
This number could be adjusted up or down with ground resistance testing for the specific conditions at the location if you really want to get that involved.

2026 NFPA-780 has some information for fences grounding and bonding in article

4.15.5 * Metallic Fences.​

and the appendix A.4.15.5

 

[garbo]

Isn't the fence already grounded? Or are the posts mounted on plastic piles of some sort?

Years ago we had a long tractor trailer scale a few feet from a several hundred foot long 8' high fence. Several times a year at least one to all four load cells would burn out after storms..Tech who replaced the load cells & serviced the scale recommended that we Install a ground rod at each end of fence nearest two ends of k scale. Fence post were set into maybe 2' of concrete. Anyway we installed ground rods and ran a #6 copper wire from first ground rod to holes drilled & tapped in every steel fence post along scale. Until p!ace closed down a few years later no load cells burned out.

 

[JWall886]

He likely is in a natural gas or oil facility. Where refunding fence grounding/bonding is done.


Most company have their own spec on this.

You likely won’t find anything regarding this in the NEC to satisfy a gas company standard for fence grounding/bonding.

I believe the NEC only hits on likely to become energized and fencing around overhead conductors/substation work.

Correct me if I’m wrong

Maybe try IEEE green book

As far as I can tell you are right about what the NEC talks about, I will look into that resource, thank you

 

[JWall886]

I know the fence around a cell tower has to be bonded.

Likely the company came up with the 20ft number basis to maintain a consistent gradient along the perimeter of the fence given your typical soil conditions.
This number could be adjusted up or down with ground resistance testing for the specific conditions at the location if you really want to get that involved.

2026 NFPA-780 has some information for fences grounding and bonding in article

4.15.5 * Metallic Fences.​

and the appendix A.4.15.5

Thank you, I will look into this to try and get a better idea

 

[JWall886]

Isn't the fence already grounded? Or are the posts mounted on plastic piles of some sort?

Yeah, this is why I say this fence doesn't need to be grounded outside of anything but company policy but that's not something I am willing to attempt to push through; it is inherently safer being grounded in the extremely minute chance someone is touching the fence when lighting strikes it which is the only reasonable thing to expect that could happen. I'm just looking for something to say, "we can ground at this distance instead of 20ft"