Can someone help with BS7430 Standard 2

[Thizo1]

I am looking some earthing formulas for the earth electrodes in Concrete encasement. I believe these are published on the BS7430 standard and I do not have this standard.I only have the South African standards. My objective is to find out how the concrete ecasement improves or lower the earth resistivity.

 

[ScottyUK]

There is a formula for calculating the resistance of a vertical electrode in a concrete backfill in section 8.5 of BS7430, but it's a copyright document and with the limitations of this text-only forum it would be almost impossible to reproduce the equation accurately. The document is available online from BSI.


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If we learn from our mistakes I'm getting a great education!

 

[7anoter4]

I agree with Scotty you cannot get the standard-entire or even part of it-without author approval.
But if you need only the embedded electrode formula you may consult also IEEE std 80 ch. 14.6 CONCRETE-ENCASED ELECTRODES. The formula is copied from:
Fagan, E. J., and Lee, R. H., “The use of concrete-enclosed reinforcing rods as grounding
electrodes,” IEEE Transactions on Industry and General Applications, vol. IGA -6, no. 4, pp. 337–348 July/Aug. 1970.
and is the same formula as per BS7430.
But what it is not in above BS is the maximum admissible current through concreted electrode.
If the current would be more than permissible then the steel rebar may expand so that cracks could happened in the concrete
or the concrete even could explode.
In IEEE std 80 there is an equation for maximum permissible current through an embedded electrode as per Ollendorff theory. There is a link to an article connected with this subject[not the same but close].

http://www.iaei.org/magazine/2001/07/concrete-encased-electrodes-and-the-grounding-electrode-system