Clamp On Ground Resistance Testers
Clamp On Ground Resistance Testers
(OP)
Can some advise experience with Clamp On ground testers as means to determine a system ground resistance value. Electrical distribution cannot be turned off therefore the use of the clamp on unit.






RE: Clamp On Ground Resistance Testers
I haven't actually used these testers, but did evaluate them a couple of years ago for possible utility use (they decided against proceeding at that time).
I suggest, as with any unfamiliar technology, that you discuss a validation/evaluation program with the manufacturer - get hold of an evaluation unit & set up appropriate field tests against standard instruments.
RE: Clamp On Ground Resistance Testers
http://www.meter-china.com/clamp%20meters.htm
http://www.alfaelectronics.com/
http://www.beha.com/beha/main.asp?language=uk
etc. for more info
RE: Clamp On Ground Resistance Testers
In the evaluation, consider that clamp-on instruments need 1½-2 inches of straight conductor for test. This may make hand-hole/valve-box-mounted rod tests impractical.
RE: Clamp On Ground Resistance Testers
RE: Clamp On Ground Resistance Testers
The 3 and 4 point ground resistance testers require open earth to drive additional ground electrodes, and are designed to give you the resitivity of the earth itself, which is part of the circuit that you are measuring with the ground loop resistance tester, but you have the added benefit of being able to take the ground connection of the device under test out of the circuit for comparison purposes.
I remember a guide from Biddle called "Getting Down to Earth" (also known as Manual 25T at Biddle) that we used to use with the ground resistance testers that provided quite a bit of useful tips on measurement and mitigation of high resistance grounds. They have a nominal charge for the manual, but you might be able to sweet-talk them for a copy as well.
AVO (the parent company for Biddle) has a link on their website with some info that you might find useful. http://www.avointl.com/products/groundtster/xtra/guides/guide.html
AEMC, the maker of the ground loop resistance tester we used, also has a manual that you can dig up online:
http://www.aemc.com/techinfo/techworkbooks/ground_resistance_testers/grdbook.pdf
Hope this gives you something to work with...