Earth Electrode Testing

[Ben Starr]

I have been tasked with carrying out some earth electrode and LPS testing using the fall of potential method but to do this I need to know the length of the rod. How do I work this out if I don't know the length?

 

[Marvo]

Isn't the fall of potential method just a fancy name for the standard 3 wire Ra test using 2 spikes at 10 and 20 meters away from the earth rod?

Why do you need to know the rod length? You need to determine that your test spikes are located away from the zone of influence of the rod but you can do this by taking multiple tests and moving the spikes by 1 meter each time. If theres little difference in results (<10%) then you can assume that you've achieved this.

 

[Engineer54]

Is this an existing LP system?? Do you have any previous test certs for the system?? If it is and older/existing system, and the individual electrode values have been previously recorded, then all you really need, is the overall Ra value. Which to comply will need to be under 10 ohms, unless otherwise asked for individual electrode tests.

Electrode testing isn't the only tests you need to perform on a LP system, all joints in the air conductors system will also need to be tested with a high current Ductor tester... Don't forget to test the Test Point(s) on the down conductors after electrode testing and reconnecting them... lol!!