I'm reviewing test results from a contractor who claims to have done a fall-of-potential test at a ground test well. The readings are taken at ten foot intervals, from 10ft to 100ft, with results starting at 1.10 ohms (10ft), a bunch of 1.00 ohms (20ft-80ft), then 0.90 ohms at 90ft and 100ft. These results aren't like any I've ever seen for a fall-of-potential test. I typically see a sharp upward curve in resistance values around 60ft or so. Is it just me, or do these results seem dubious?
Fall of Potential Test Results
- Thread starter MatthewEE
- Start date
ptonsparky
Tom
- Occupation
- EC - retired
It’s been a decade or two since I had to do those.
Any chance he is parallel to a metallic piping system? Fencing?
Any chance he is parallel to a metallic piping system? Fencing?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Is there any buried metal, like a storage tank, in his measuring path.
Is this undisturbed soil or has it been compacted or filled?
Is this undisturbed soil or has it been compacted or filled?
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Sounds like a great big voltage divider.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
I would be surprised if they were able to find undisturbed earth within 100' of the hanger.
Are you trying to find the actual resistance to ground or just develop a baseline database?
Trying to find actual resistance to ground.