True or False

[A/A Fuel GTX]

A building with steel structural members that don't meet the requirement of 250.52(A)(2) but after applying 250.104(C), the structural members become a grounding electrode anywhere that is accessible throughout the structure. So in other words, ANY building with steel structural members should be considered a grounding electrode by virtue of the structural members.

 

[Dennis Alwon]

False. The structural steel that does not meet 250.52 is not an electrode. This does not mean it doesn't have to be bonded where it is likely to be energized. The same is true with water pipe. If 10' of metallic pipe is not in the ground then it is not an electrode but it must be bonded if it is metallic in the house.

 

[Gregg Harris]

A building with steel structural members that don't meet the requirement of 250.52(A)(2) but after applying 250.104(C), the structural members become a grounding electrode anywhere that is accessible throughout the structure. So in other words, ANY building with steel structural members should be considered a grounding electrode by virtue of the structural members.

If it meets one of the requirements

(2) Metal Frame of the Building or Structure. The metal frame of the building or structure that is connected to the earth by one or more of the following methods:

1. At least one structural metal member that is in direct contact with the earth for 3.0 m (10 ft) or more, with or without concrete encasement.
2. Hold-down bolts securing the structural steel column that are connected to a concrete-encased electrode that complies with 250.52(A)(3) and is located in the support footing or foundation. The hold-down bolts shall be connected to the concrete-encased electrode by welding, exothermic welding, the usual steel tie wires, or other approved means.

 

[A/A Fuel GTX]

If it meets one of the requirements

(2) Metal Frame of the Building or Structure. The metal frame of the building or structure that is connected to the earth by one or more of the following methods:

1. At least one structural metal member that is in direct contact with the earth for 3.0 m (10 ft) or more, with or without concrete encasement.
2. Hold-down bolts securing the structural steel column that are connected to a concrete-encased electrode that complies with 250.52(A)(3) and is located in the support footing or foundation. The hold-down bolts shall be connected to the concrete-encased electrode by welding, exothermic welding, the usual steel tie wires, or other approved means.

Ok, so there are only two possible scenarios that deem structural building steel an "electrode". If I bond structural steel to another listed electrode via 250.66 conductor size, it is not considered a "made" electrode by virtue of a physical connection to the said listed electrode? The steel is only considered bonded, if I understand this correctly.

 

[Gregg Harris]

Ok, so there are only two possible scenarios that deem structural building steel an "electrode". If I bond structural steel to another listed electrode via 250.66 conductor size, it is not considered a "made" electrode by virtue of a physical connection to the said listed electrode? The steel is only considered bonded, if I understand this correctly.

That would be correct, only bonded if it met the other criteria,

1. At least one structural metal member that is in direct contact with the earth for 3.0 m (10 ft) or more, with or without concrete encasement.
2. Hold-down bolts securing the structural steel column that are connected to a concrete-encased electrode that complies with 250.52(A)(3) and is located in the support footing or foundation. The hold-down bolts shall be connected to the concrete-encased electrode by welding, exothermic welding, the usual steel tie wires, or other approved means.

it would be a grounding electrode.

 

[A/A Fuel GTX]

Ok, so I go into a large steel structured building and need to set a new transformer creating a SDS. How do I determine if the steel is an electrode or just bonded, regarding the connection between X0 and the grounding electrode system I must make? If the steel is not an electrode, the grounding electrode conductor could be extremely long going all the way back to the service equipment.

 

[Dennis Alwon]

Ok, so I go into a large steel structured building and need to set a new transformer creating a SDS. How do I determine if the steel is an electrode or just bonded, regarding the connection between X0 and the grounding electrode system I must make? If the steel is not an electrode, the grounding electrode conductor could be extremely long going all the way back to the service equipment.

I am not sure that is an issue as long as the steel is bonded I think you can use the steel if it is directly connected to a grounding electrode. 250.68(C)(2)

 

[A/A Fuel GTX]

So actually, the bonded steel structural members do become an electrode which contradicts 250.52(A)(2)?

 

[petersonra]

So actually, the bonded steel structural members do become an electrode which contradicts 250.52(A)(2)?

actually it might be more correct to say it becomes part of the GEC.

some of this stuff is based on what is practical.

I can't ever recall seeing a structural member in contact with earth for 3 m. However, I am pretty sure that dozens or hundreds of steel members bolted to concrete piers make a very fine GE, even if technically it does not qualify.

kind of like the concrete base of light poles. probably on the whole just about a perfect GE, but unless you put the right amount of metal in it and bond it just right it does not count.