[RE-wrenches] Lightning protection (was Delta LA's)

[R Ray Walters]

2 electrodes lets you off the hook for NEC, but not with the lightning hurling gods. 
New Mexico code has actually dropped the 2 rod rule as well, you have to install a Ufer ground in all new construction there.
WIth dry rocky soil, your impedance with 2 rods can still be hundreds of Ohms.

The Amprobe's lowest range is .025  to .25 ohm. The lowest reading I've seen was .95 ohm on a commercial building in Hawaii.

Ray

On Sep 15, 2010, at 6:25 AM, Darryl Thayer wrote:

> If you are doing Off Grid is it enough just to drive two ground rods?  and make a connection between them?  Also what is the lowest Ohm reading your DGC 1000 meter can read?
> Thanks  
> 
> --- On Wed, 9/15/10, R Ray Walters <ray at solarray.com> wrote:
> 
> From: R Ray Walters <ray at solarray.com>
> Subject: Re: [RE-wrenches] Lightning protection (was Delta LA's)
> To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
> Date: Wednesday, September 15, 2010, 12:34 AM
> 
> Hi Dave;
> 
> I bought an Amprobe DGC 1000 for around $1100. It takes seconds to get a reading, without taking any connections loose or shutting off power.
> There are much cheaper units (3 point fall of potential type) to be had for under $500. They take more time, but also would be better for off grid measurements.
> 
> R. Walters
> 
> On Sep 14, 2010, at 8:04 PM, Dave Palumbo wrote:
> 
>> What Ray Walters said was the truth. Resistance to ground should be very low. How many dollars is that tester you use Ray? We don’t own one. On the wish list. 
> 
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