Grounding

[Adnan Hasan]

24,000 m² (160x150 m) Foundation Area of hospital reinforced with steel bars for structure was covered by matrix of 30x3 mm Galvanized steel strip as Grounding conductor then the Grounding matrix bonded to the structure bars by galvanized steel clamp with a Span of 2 m between every two bonds and the grounding matrix connected to copper earth electrode (earth pits) with a span of 10-20 m between every two earth pits.
Questions

1. Is the Grounding for foundation Mandatory? I experienced some buildings without grounding for foundation
2. Is it permitted to use this grounding matrix as a path to drain the fault current incurred between phases or phase to ground?

 

[jusme123]

see 250.50 of the NEC

 

[m sleem]

see 250.50 of the NEC

I would think the OP doesn't meet the exception of 250.50 where the building is not existing.

And, 250.52(a)(3) permits it.

 

[jusme123]

 

[jusme123]

I would think the OP doesn't meet the exception of 250.50 where the building is not existing.

And, 250.52(a)(3) permits it.

I don't know if he has a new building or is working in an existing one, but 250.50 and 250.52 should answer his questions.

 

[Adnan Hasan]

View attachment 8196

I agree with your answer.
what about my question 1?

1. Is the Grounding for foundation Mandatory? I experienced some buildings without grounding for foundation

 

[SG-1]

The NEC does not mandate any particular grounding method. The engineering firm designing the building's electrical system may choose one method over another to achieve a particular goal.

 

[jusme123]

250.50 states, " All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the grounding electrode system."

(A)(1)- Metal Underground Water Pipes
(A)(2)- Metal Frame of the Building or Structure
(A)(3)- Concrete Encased Electrode
(A)(4)- Ground Ring
(A)(5)- Rod and Pipe Electrodes
(A)(6)- Other Listed Electrodes
(A)(7)- Plate Electrodes