Changing Copper Ground grid to steel due to cathodic protection requirements

[dbadger]

The NEC requires copper or aluminum grounding conductor and rods. However, to use cathodic protection to protect copper takes a lot of current. Is there any way to use Steel grounding system and still follow the NEC?

 

[roger]

Rods can be steel, see 250.52(A)(5).

 

[tom baker]

To answer your question, no.
Where in the NEC are copper and aluminum ground rods aluminum allowed?

 

[dbadger]

To answer your question, no.
Where in the NEC are copper and aluminum ground rods aluminum allowed?

I am not trying to use both. Is copper my only option for a grounding ring? 250 (A) (4)

 

[roger]

I am not trying to use both. Is copper my only option for a grounding ring? 250 (A) (4)

The rods or the conductor?

 

[roger]

Once again the rods can be steel. The coductor will need to be copper

 

[dbadger]

The rods or the conductor?

Conductor.

 

[dbadger]

Once again the rods can be steel. The GEC will need to be copper.

I have to cathodic protect the grounding ring and rods. Have you seen projects that use steel instead of copper because of the current required to protect the copper? Where the project did not follow NEC code.

 

[roger]

The NEC has no provision for using steel as a GEC. I have never worked anywhere that ignored the code besides some minor industrial projects that were under engineering supervision


I wouldn't be to concerned, the ground ring will not be doing much anyways. GES's don't do much and are greatly overrated.

 

[winnie]

Copper is quite 'noble' and generally has a long life underground without any sort of protection.

Sterl ground rods are permitted, but they need to be listed and are certainly coated with some other metal, eg copper clad or heavily gslvanized.

Bare steel is permitted if it is the rebar in a 'concrete encased electrode'.

What circumstances are you dealing with where copper would require cathodic protection?

Jon

 

[dbadger]

Copper is quite 'noble' and generally has a long life underground without any sort of protection.

Sterl ground rods are permitted, but they need to be listed and are certainly coated with some other metal, eg copper clad or heavily gslvanized.

Bare steel is permitted if it is the rebar in a 'concrete encased electrode'.

What circumstances are you dealing with where copper would require cathodic protection?

Jon

Our underground steel structure requires cathodic protection, and the underground structure is connected to the ground grid/ring. So by default, the ground ring is going to be cathodically protected. I am scared the copper will be more cathodic than the structure itself. And the structure will act anode.

 

[synchro]

The NEC requires copper or aluminum grounding conductor and rods. However, to use cathodic protection to protect copper takes a lot of current. Is there any way to use Steel grounding system and still follow the NEC?

If you had copper and steel underground with an electrical connection between them, an electrochemical cell (similar to a battery) would be formed with copper as the cathode and steel as the anode. The steel would act as a sacrificial anode and effectively protect the copper, and so it would be performing cathodic protection of the copper in a passive way without any externally applied DC current.

However, as winnie mentioned copper is on the "noble" side of the electrochemical series, and normally would not need cathodic protection.

 

[winnie]

Our underground steel structure requires cathodic protection, and the underground structure is connected to the ground grid/ring. So by default, the ground ring is going to be cathodically protected. I am scared the copper will be more cathodic than the structure itself. And the structure will act anode.

You are correct. The steel will sacrifice itself protecting the copper.

This may not be a problem if the exposed area of the steel is much larger than the area of the copper, but to evaluate that you need an engineer who works with underground corrosion issues.

The NEC does not permit steel to be used as a ground ring. So if you have a requirement for an NEC ground ring then you are stuck with copper.

What drives the requirement for a ground ring? Could a suitable steel structure provide the necessary functionality without being an NEC ground ring?

Jon

 

[JPalmer]

The NEC has no provision for using steel as a GEC. I have never worked anywhere that ignored the code besides some minor industrial projects that were under engineering supervision


I wouldn't be to concerned, the ground ring will not be doing much anyways. GES's don't do much and are greatly overrated.

Roger can you help me understand what a GES refers to. Is that acronym Grounding Electrode System.

Also, can you clarify your statement that the ground rings don't do much.

 

[roger]

Yes, you are correct it is Grounding Electrode System.

In as much as grounding plays an important part in our electrical installations many systems are over done. A couple of ground rods will perform over and above what is necessary in most cases. The magical triad, miles of copper, multiple rods, do not really change this fact.

I was on a project with an $80,000 ground ring (it was a few acre building) that still had lightning damage occure

 

[zbang]

@JPalmer Can you tell us something about the application and local environment? Grounding for a single well in a cornfield will be different from a substation and from a many-tenant radio tower.