25 ohm ground rod

[petersonra]

I am reading a book that states, "the resistance of a cylinder of spring water 1-yard long is equal to that of the resistance of a copper conductor of the same diameter 7X the distance of the earth to the moon."

I wonder where they came up with such a number.

 

[brian john]

The lower the ohms the less chance of surface arcing.

In relation to ground electrode resistance? How so?

 

[dlhoule]

The lower the ohms the less chance of surface arcing.

I didn't say it was your fault. I said I was going to blame you

Thanks for the credit stickboy1375. What is it I did or didn't do this time. Its about time I get credit for something. :wink:

 

[ramsy]

If you could use a CEE you wouldn't ever need ground rods.

What is CEE, the only thing I came up with was this:
CEE - Commission on Rules for the Approval of Electrical Equipment

 

[George Stolz]

Concrete encased electrode.

 

[stickboy1375]

The lower the ohms the less chance of surface arcing.

In relation to ground electrode resistance? How so?

To answer your question, a bolt of lightning is about 40,000 amperes, (probably alot more) so say your ground rod has 1 ohm of resistance, E=IR, 40,000 * 1 = 40,000 volts, now surface arcing occurs at about 30,000 volts, so lets say your ground rod is at 1/10th of an ohm, that would be around 4000 volts... In theory, once the voltage exceeds the resistance thats when surface arcing occurs which is what causes fires, the whole reason why we drive ground rods to begin with...

 

[RB1]

I have to agree that the biggest arc discharge I ever saw was lightning. And it was on the surface.

P.S. When y'all get through with the spring water/ moon test, I sure would like the scrap.

 

[tallgirl]

I have to agree that the biggest arc discharge I ever saw was lightning. And it was on the surface.

You mean, like this?

http://www.lightningsafety.com/nlsi_lhm/Radials.pdf

P.S. When y'all get through with the spring water/ moon test, I sure would like the scrap.

Sure, all you need is a rocket that can take you half way to the moon to get it. I'm sure NASA has a few of them lying around you might be able to buy for a few hundred million dollars