Mike Lamb Posted November 18, 2010 Report Share Posted November 18, 2010 This house has 2 grounding rods outside near the meter. One run down stream from the other. Any reasons come to mind? Click to Enlarge 86.65 KB Click to Enlarge 99.8 KB It also had 2 grounding jumps over the water meter? Click to Enlarge 47.04 KB Link to comment Share on other sites More sharing options...
Brandon Whitmore Posted November 18, 2010 Report Share Posted November 18, 2010 Hi Mike, Read this: http://www.electriciantalk.com/f5/2-ground-rods-3238/ Link to comment Share on other sites More sharing options...
Mike Lamb Posted November 18, 2010 Author Report Share Posted November 18, 2010 So it creates less resistance to ground. Thanks, Brandon. This is new to me. Link to comment Share on other sites More sharing options...
Chad Fabry Posted November 18, 2010 Report Share Posted November 18, 2010 It's required here. Link to comment Share on other sites More sharing options...
Jim Port Posted November 18, 2010 Report Share Posted November 18, 2010 Those rods should be driven below ground. The Code calls for 8' of direct ground contact. Rods are commonly 8' long so leaving a few inches out does not give the required ground contact. Link to comment Share on other sites More sharing options...
Tom Raymond Posted November 18, 2010 Report Share Posted November 18, 2010 Well, then how do you find them? How do you verify proper clamps? Link to comment Share on other sites More sharing options...
Jim Katen Posted November 18, 2010 Report Share Posted November 18, 2010 Well, then how do you find them? How do you verify proper clamps? That should be verified at the time of installation. Afterwards there's, in theory, no reason to verify it. Ultimately, if someone wanted to verify proper grounding, he could perform resistance testing: http://ecmweb.com/grounding/electric_gr ... echniques/ In addition to driving rods fully into the soil, I'd recommend burying the conductor to protect it from weed whackers & such. - Jim Katen, Oregon Link to comment Share on other sites More sharing options...
Marc Posted November 18, 2010 Report Share Posted November 18, 2010 Well, then how do you find them? How do you verify proper clamps? That should be verified at the time of installation. Afterwards there's, in theory, no reason to verify it. - Jim Katen, Oregon Theory has its shortcomings. Ground clamps do sometimes come loose, often enough that I've boilerplate for it. Marc Link to comment Share on other sites More sharing options...
hausdok Posted November 18, 2010 Report Share Posted November 18, 2010 Give the cable a gentle tug. That's what I do when I can actually see it. If the first rod is close to where the cable enters the soil, it should not give more than a couple of inches. If it feels firm I make a presumption that it's firmly clamped to its rods below grade. Every once in a while I'll have a cable come right up out of the soil with the clamp attached or without a clamp attached. If it's a short section that just disappeared below grade it's obvious that there aren't two driven electrodes and I write it up. Sometimes the cable will come up with the clamp attached and the end will trail off below grade to the next electrode. If that continued cable feels solid I make a presumption that it's only disconnected from one electrode. I don't dig down to find the first electrode and then try to follow the cable to the second electrode. I'm not about to start rooting around next to the foundation with a spade. ONE TEAM - ONE FIGHT!!! Mike Link to comment Share on other sites More sharing options...
Douglas Hansen Posted November 19, 2010 Report Share Posted November 19, 2010 Give the cable a gentle tug. That's what I do when I can actually see it. If the first rod is close to where the cable enters the soil, it should not give more than a couple of inches. If it feels firm I make a presumption that it's firmly clamped to its rods below grade. Please don't do that Mike. There are enough situations where current is running through the GEC, albeit at less than line voltage, where you could end up creating a shocking experience for yourself. I think if you are that curious about what might be going on a few inches below the top of the soil, you can scrape away some of the dirt. The general safety principle here is that grounding connections of all sorts are first-to-make, last-to-break, and that on the off chance something could become energized by breaking it, you certainly don't do it barehanded. and back to the first topic - the NEC has required this second ground rod since the 1918 edition. The wording then was actually clearer than it is today: Where, because of dry or other high re- sistance soils it is impracticable to obtain artificial ground resistance as low as 25 ohms, two such grounds 6 feet apart if practicable must be installed, and no requirement will be made as to resistance. There was no scientific basis for the 25 ohm rule back then, and the only rationale for keeping the rule seems to be "well - it's been working OK to have this in the code." For contrary evidence, see the thread on CSST bonding. Douglas Hansen Link to comment Share on other sites More sharing options...
hausdok Posted November 19, 2010 Report Share Posted November 19, 2010 Oops! [:-dunce] Thanks, Teach! OT - OF!!! M. Link to comment Share on other sites More sharing options...
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