fall of potential testing

[Wire-Smith]

is fall of potential testing practical for outside processing plants, i'm guessing larger than 20 acres.

all of the structures have ground rings and they are all connected

by my understanding of fall of potential testing you should be 8 to 10 times the largest diagonal of the ring away from the ring with your injector

so say a new structure is built inside the existing facility and a new ring installed.

1-if you tie the new ring to the existing stuff and do the fall of potential test don't you need to test outside of the facility? 8 to 10 times further away from entire facilities interconnected rings. your green rod at the ring , injector 8 to 10 x away and measurement probe in the 60% area(multiple spots)

2- even if you leave the new ring unhooked from existing do you know anything by testing outside of only the new ring (the existing is going to influence (lower) the readings right?)

 

[Wire-Smith]

is there a better way of testing ground connection for this scenario?

 

[Wire-Smith]

would star delta method work well? and could the new system be connected to the old while doing this?

 

[tom baker]

is there a better way of testing ground connection for this scenario?

Yes use a clamp on ground resistance tester. This only works when the ground under question is connected to the electrical system. I belive AEMC makes such a tester

 

[Wire-Smith]

Yes use a clamp on ground resistance tester. This only works when the ground under question is connected to the electrical system. I belive AEMC makes such a tester

i do this also, i use a fluke. engineering doesn't approve this method though, ieee kind of spells out that you should do fall of potential and they also mention it's not practical in some situations but you kind of have to test and then find out it's not really practical, i wish api or ieee would publish a study or something on this scenario