On 17 Sep 2006 17:29:09 -0700, "BobK207" wrote:


Tom The Great wrote:
On 16 Sep 2006 23:41:55 -0700, "BobK207" wrote:



If a small diameter ground rod (1/2" or 5/8") doesn't give the 25 ohms
(or less) to ground.....would a larger (3/4" or 1") diameter rod in the
same soil do better?

Is the soil the culprit or the soil / rod contact resistance? The
larger diameter rod contacts more soil..better grounding behavior?

cheers
Bob


IMHO,

I've found (through discussing with electricians) that soil conditions
have a greater effect on grounding effects, when comparing 1/2 to 1"
rods.

Remember, if you are concerned about resistance for code, just drive
the second rod. Then you don't even have to check ohms, since even if
you don't have the min, the code only requires a second rod.

The idea is that everyone grounds the 'neutral' the voltage on teh
grid will be 'stablized' so you are only adding a drop to the bucket
(the grid) and helping your line to your house.

FYI: Ground rods aren't for ground faults.

later,

tom @ www.BlankHelp.com


I know that the code says if you fail the 25 ohm level drive another
rod 6' away.

But I was curious about the variables that effect the performance of
the rod / soil system. I also really liked the technique that someone
posted as to how to test a ground rod; simple & pretty cool

Don't everyone jump on me but I'm not a huge fan of codes in
general.....they tend to substitute blind adherence for understanding
of what's rally going on

ie what is the intent behind the code.

also having worked on committees I know that codes tend to minimum
standards that everyone in the room at the time could live with; either
due to lateness or lack of energy

imho:

Codes are designed for safe operation of you electrical system. The
completion of work below codes is dangerious, and the completion of
work 'over' codes is just extra money spent. Also, if you don't do
'standard' work, another electrician following you will have to
'figure out' what you did.

So, depending on who is spending the money, you might be wasting it.

later,

tom


if one has ground rod that "fails" & puts in another.....conceivably
one could still be above the 25 ohm level but still "meet code".

I'd rather know that my installation was good & I'd rather know what
parameters improve my chances of having a good installtion.

that's why I asked if bigger was better.

looks like longer is better.... I gues that's the way things go

cheers
Bob