Instrument Earthing Resistance

Irrigate the ground with seawater.

http://cr4.globalspec.com/thread/13720#comment137246

I fully subscribe to most of all said in the thread before me. But specifying 1 Ohm separate ground, as if that would be a solution is bordering on insane. Even if you measure it within spec now, it wont be in the next heatwave, when the ground dries out completely. Nor will it do its duty, when somebody puts in a heavy equipment ground nearby. It maybe even be done for your neighbour you being unaware. Production equipment HAVE to be grounded. Instruments do not (when they use low voltages), or provided ground independent path back to wherever. The equipment is off-the-shelf including converters for sensors and instruments of the preceding generation. As soon as your instrumentation run is independent from the ground bounces of the sensor end you are home free. In the office you reconvert back, and your installation should be invisible.

Convincing the customer is another thing entirely.

HI

Increase the number of earth rods such that you will get the resistance less than 1 ohm . The spacing between 2 earth electrodes should be minimum 6M. Also check the earth cable size , make the size a bit larger to achive the desired resistance .

Regards

Dhilju

Thanks ,We are also following the same.

We have Drived earth rods at 4 places, every places 3-4 Rods were used.

All together we connected and we got 2 ohms.

Because the site condition is like as free sand.

This site is last 3 year back only converted as land before it was sea.

Still we are increasing the no of earthing places and connected to Parallel.I hope we will get less than 1 ohm.

Thanks and regards,
karthik.