Ohms check

[nizak]

Is there any way to test grounding electrode resistence by just using a single digital multimeter? Our inspectors have the $2K clamp on type meter that they simply put around the conductor and it gives them a read out.Quite honestly I have never attempted to check for 25 ohms or less. Thanks.

 

[ritelec]

That's a good question which I'd be interested in seeing the responses.

Many moons ago I wired a McMansion, There was a well (plastic pipe).

I drove two ground bars. Stripped some wire to one lead on a multi meter, stuck it in the dirt and stepped on it. The other lead went to the neutral in the meter pan. In my minds eye I think I remember reading 20.

Right or wrong that's what I did and walked away from it.

Never tried taking readings on any other install as the rest had water pipes....and I just never checked....

Interestingly watching,

Rich

 

[roger]

Is there any way to test grounding electrode resistence by just using a single digital multimeter? Our inspectors have the $2K clamp on type meter that they simply put around the conductor and it gives them a read out.Quite honestly I have never attempted to check for 25 ohms or less. Thanks.

Not safely and accurately.

Roger

 

[zog]

Is there any way to test grounding electrode resistence by just using a single digital multimeter? Our inspectors have the $2K clamp on type meter that they simply put around the conductor and it gives them a read out.Quite honestly I have never attempted to check for 25 ohms or less. Thanks.

No, and the clamp meter does not work on single electrode systems anyways. Plus the clamp on reading has no proof that it is accurate. THe only way to test a single rod accuratly and per any recognized standards is by using the fall of potential method with a real ground resistance test set,

This has been covered many times here before if you want to read up on it but long story short, just drive a 2nd rod and move on.

 

[Benton]

No, and the clamp meter does not work on single electrode systems anyways. Plus the clamp on reading has no proof that it is accurate. THe only way to test a single rod accuratly and per any recognized standards is by using the fall of potential method with a real ground resistance test set,

This has been covered many times here before if you want to read up on it but long story short, just drive a 2nd rod and move on.

I couldn't say it better:happyyes::happyyes:

 

[ksmith846]

Out of curiosity why are they checking anyway? Just put in a second rod 6 feet away and move on. No need to prove 25 ohms at that point.

Am I missing something here?

 

[BAHTAH]

Ohms Check

Ohms Check

If it's new, UFER ground. If it's an upgrade I usually go with two ground rods and several places I have been the local AFJ requires two ground rods because they don't want to measure the ohm's any more than we do and even if you do measure, soil conditions change and so do the Ohm's. I have done some jobs where the Bureau of Mines was inspecting and they had me driving ground rods until I got a correct Ohm reading. If you just can't get a good reading then your into the Chemical Ground Rods.

 

[jumper]

No, and the clamp meter does not work on single electrode systems anyways. Plus the clamp on reading has no proof that it is accurate. THe only way to test a single rod accuratly and per any recognized standards is by using the fall of potential method with a real ground resistance test set,

This has been covered many times here before if you want to read up on it but long story short, just drive a 2nd rod and move on.

I couldn't say it better:happyyes::happyyes:

I am with Zog and Benton.:thumbsup:

If speced for testing, sub it out.