NEC 250.194(A) fence grounding

[TPhan]

1/ The code says: "Where metal fences are located within 5 m (16 ft) of the exposed electrical conductors or equipment, the fence shall be bonded to the grounding electrode system with wire-type bonding jumpers". What is the "grounding electrode system"?

If I connect the fence to many ground rods, should all the ground rods to be connected together? or is it OK if all the rods are not connected together?
If all the rods must connected together, should all the ground rods also connect to the ground ring in the equipment pad?

2/ The code says "Where metal fences are located within 5 m (16 ft) of the exposed electrical conductors or equipment," then the "Bonding jumpers shall be installed at each fence corner and at maximum 50 m (160 ft) intervals along the fence."

For example of a rectangular fence ABCD, if there is only 1 place in AB side where the exposed conductor is within 16ft, then should we ground the whole fence with 160ft interval? or should we just ground the fence in only 1 side of AB to the corners of A and B (the other side of BC, CD, and DA will not be grounded)?

In the case that the AB side is so long, for example 1000', should we have to ground all the length or when to stop?

3/ The code says "Where bare overhead conductors cross the fence, bonding jumpers shall be installed on each side of the crossing."

How far away the bonding jumper to be install from each side of the crossing? 5ft or 10ft or what?
When grounding the fence with overhead line crossing, when should we stop grounding (160ft from each side of the crossing?) or we have to ground the whole fence?

Thank you very much.

 

[don_resqcapt19]

What are you working on that you have exposed electrical conductors and equipment?

 

[TPhan]

What are you working on that you have exposed electrical conductors and equipment?

Yes, the bare MV overhead line is running along the fence. The post for overhead line is 15' away from the fence so the overhead line may be within 16' and the fence has to be grounded.

 

[don_resqcapt19]

Is this a new fence that is going to be installed? Is the overhead line existing? What code and section are you citing?

 

[TPhan]

Is this a new fence that is going to be installed? Is the overhead line existing? What code and section are you citing?

I am designing the new fence and poles. There are many times we have to cross the fence with overhead line. Sometimes the overhead line is running in parallel with the fence. The reference code is 250.194(A). I just want to clarify the grounding in the code as it is not clear to me.

 

[don_resqcapt19]

Note the parent text of that section. It only to substations. It does not apply just because there are overhead wires in the area where you are installing a fence.

250.194 Grounding and Bonding of Fences and Other Metal Structures.
Metal fences enclosing, and other metal structures in or surrounding, a substation with exposed electrical conductors and equipment shall be grounded and bonded to limit step, touch, and transfer voltages.[/quote[
Since you are not working at a substation, there is no reason to read 250.194(A) or (B).

Is your proposed fence outside the easement for the overhead line?

 

[TPhan]

I understand that the system is not the substation, but there is no other place mention about the fence grounding. In the case of an MV overhead line crossing the fence or within 16' within the fence. What is the proper way to ground the fence. Which code/standard should I follow.

 

[hbiss]

What is the proper way to ground the fence. Which code/standard should I follow.

It's not required to be grounded.

-Hal

 

[retirede]

I understand that the system is not the substation, but there is no other place mention about the fence grounding. In the case of an MV overhead line crossing the fence or within 16' within the fence. What is the proper way to ground the fence. Which code/standard should I follow.

Which means there is no requirement for grounding.

 

[don_resqcapt19]

I understand that the system is not the substation, but there is no other place mention about the fence grounding. In the case of an MV overhead line crossing the fence or within 16' within the fence. What is the proper way to ground the fence. Which code/standard should I follow.

Why do you think it needs bonding? If you are just looking at bleeding of potential induced voltages, the metal fence posts in the earth will do that.

 

[TPhan]

Why do you think it needs bonding? If you are just looking at bleeding of potential induced voltages, the metal fence posts in the earth will do that.

how about the overhead line crossing the fence, if the line is broken and touching the fence? I think we may ground the fence even it is not in the substation.

 

[hbiss]

If the MV line falls and comes in contact with the fence, people will know to stay away from it real quick.

-Hal

 

[don_resqcapt19]

how about the overhead line crossing the fence, if the line is broken and touching the fence? I think we may ground the fence even it is not in the substation.

I see no reason to ground it. Medium and high voltage lines cross lots of things that do not have any additional grounding.
The utility protective relaying should be set to clear a ground fault with the line on the actual ground. The metal fence with its posts in the earth should permit an even higher ground fault current and clear the fault even quicker.

 

[TPhan]

1/ The code says: "Where metal fences are located within 5 m (16 ft) of the exposed electrical conductors or equipment, the fence shall be bonded to the grounding electrode system with wire-type bonding jumpers". What is the "grounding electrode system"?

If I connect the fence to many ground rods, should all the ground rods to be connected together? or is it OK if all the rods are not connected together?
If all the rods must connected together, should all the ground rods also connect to the ground ring in the equipment pad?

2/ The code says "Where metal fences are located within 5 m (16 ft) of the exposed electrical conductors or equipment," then the "Bonding jumpers shall be installed at each fence corner and at maximum 50 m (160 ft) intervals along the fence."

For example of a rectangular fence ABCD, if there is only 1 place in AB side where the exposed conductor is within 16ft, then should we ground the whole fence with 160ft interval? or should we just ground the fence in only 1 side of AB to the corners of A and B (the other side of BC, CD, and DA will not be grounded)?

In the case that the AB side is so long, for example 1000', should we have to ground all the length or when to stop?

3/ The code says "Where bare overhead conductors cross the fence, bonding jumpers shall be installed on each side of the crossing."

How far away the bonding jumper to be install from each side of the crossing? 5ft or 10ft or what?
When grounding the fence with overhead line crossing, when should we stop grounding (160ft from each side of the crossing?) or we have to ground the whole fence?

Thank you very much.

Thank you for all of your inputs of not applying the grounding for the fence if it is not in a substation. But it the case of a substation, the code is still not clear for me. Could you answer the above for the substation?

 

[tom baker]

We may not know the answer. Substations are more of an NESC area.
I don’t recall ever seeing a fence grounding question here. Did you look in the NEC handbook or try professor google?

 

[TPhan]

We may not know the answer. Substations are more of an NESC area.
I don’t recall ever seeing a fence grounding question here. Did you look in the NEC handbook or try professor google?

I searched Google and ChatGPT (-: already but I could not find the my needed answer. There is a Youtube video about it

I may try to read IEEE 80 and NESC for more details.

 

[hbiss]

That's a substation.

-Hal

 

[mikeames]

Let's be clear. A metal fence in the ground is already grounded much like an inground pool. Bonding it means connecting it to the nearby systems Grounding electrode system that your referring to. Bonding it every 160 feet and around corners is to maintain the electrical integrity of the fence since its likely to be in sections. You don't drive a ground rod at every post. You could but why be silly and waste money.

 

[electrofelon]

Let's be clear. A metal fence in the ground is already grounded much like an inground pool. Bonding it means connecting it to the nearby systems Grounding electrode system that your referring to. Bonding it every 160 feet and around corners is to maintain the electrical integrity of the fence since its likely to be in sections. You don't drive a ground rod at every post. You could but why be silly and waste money.

Years ago I was helping out on a 2 meg solar install. It had a metal fence around it with the metal pipe posts driven into the ground. It was on the plans to drive a ground rod every 100' and bond it to the fence and post. Fortunately I wasn't assigned that job. I would have been so embarrassed at the stupidity, afraid I would get laughed at, heckled, and made fun of by observers. Then there is the possibility that aliens are watching us, and imaging them just laughing at me driving ground rods to "ground" this fence..... It just would have been very stressful and traumatic.