grounding conductor size

Feb 01, 2006 2 Replies

Hi, I have a problem in determining the cross section to be used for the ground conductor for a ground with earth resistivity of 170. I basically need a formula to calculate the ground conductor cross section for this rho. And this is not for grounding grid but for underground feder?



I apprecite if any body can write the formula for me. I have all the other info, like ambient temp. etc.



Thanks in advance...



Sunny



I think i need to be more elborate on my problem. I have a design question about cross section of underground insulated conductor buried in a soil with earth resitivity of 170. So considering this a high ground resitivity, I want to be sure about the formula used to determine the cross section of the conductor based on the earth resitivity (rho) value. I believ it requires additional data like ambient temp, temperature of the conductor...I have all that, but have to have the formula to determine my cross section of underground feeders.

Thanks in advance.

Sunny

I believe IEEE 835 has the calculations for this. I don't know that soil resistivity would matter. Soil thermal conductivity would matter.

j

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