Ufer grounding

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kfenn22

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Does anyone have a formula for calulation ufer ground?
Is it Possible? I sure there are alot of variables.

or anyone have a good link to detailed information about Ufer ground?
 
There are calculations for # of ground rods it takes to achieve a certain a desired ohms to earth. I was just trying to figure out what impact the Ufer has on those calculations. I know the Ufer will improve the grounding system, just trying to fixture how much improvement there will be.
 
I am not familiar with any calculations but Bryan Holland did send out a study by some scientists a while back, if you want to p.m. me i will try and send it to you or if it is on the net I am not sure.
 
I see from your profile that you are an EE

I would expect that a installed CCE system could be evaluated inseverl manners . The fall of potential method may work. I would be interested to see responses on this issu myself.
 
There is an equation in IEEE Std 80, IEEE Guide for Safety in AC Substation Grounding for the resistance of a vertical rod encased in concrete.

RCErod = {rhoc?ln(Dc/d)+rho?[ln(8?L/Dc)-1]}/(2?pi?L) ohms

Where L is the rod length in m
Dc is the diameter of the concrete in m
d is the rod diameter in m
rhoc is the resistivity of concrete in ohm-m (between 30 and 90)
rho is the soil resistivity in ohm-m

You could use the diameter of a single rebar and get a conservative answer for a pier foundation with a rebar cage.
 
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