Grounding Rod Info

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On Sun, 13 Jul 2003 00:59:15 GMT, "volts500"

Volts: With a 35 foot run from my panel to the acceptable spot on your water pipe, what size wire should I run (or would _you_ run on your house if you had that situation ?)
I always heard that if the run was much longer than 5 feet that you would have problems dissipating a lightning type surge. I can get a short run like that to a grounding rod (and then another 5 to a second rod from the first). But, there's no way I'm going to get that sort of run to the water pipe. Also, eventually I plan to put in a whole house lightning/surge protector, I'd like to be ready for that - and fix the current issue right now.
Bob
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Code does not define how to measure resistance of earth ground. The same application notes that demonstrate how to install a more serious 'single point earth ground' (which is labeled MGB in the picture): http://www.leminstruments.com/pdf/LEGP.pdf (figure on page 14 or) http://leminstruments.com/grounding_tutorial/html/index.shtml (section entitled "Measuring Ground Resistance at Cellular Sites,Microwave and Radio Towers")
That Lem Instrument application describes measuring earth ground resistance since that is what they are selling.
'nuther Bob wrote:

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Code does not state distance to water pipe because code addresses human safety issues. Wire length in a residence is irrelevant for human safety. But wire longer than 10 feet has adverse effects to earthing for surge protection. Again, code is only concerned with wire resistance. Surge protection worries about wire impedance which is why that wire must be short and other requirements (no splices, no sharp bends, etc).
Transistor safety (also known as surge protection) is beyond scope and purpose of the NEC. After all, who creates NEC requirements? National Fire Protection Association - because code is written to protect human life.
But for transistor safety, that ground wire length and how the earthing system is connected (single point earth ground) exceeds what code requires. We must enhance an 'NEC required' earthing system to also provide an effective 'surge protection' earthing system.
For example, a ground wire can be grouped with other wires to meet NEC. But for effective surge protection, that earthing wire must be separate from other wires - so as to not create induced surges on those other wires. Ground wire must not be in close electromagnetic proximity with other non earthing wires. Code does not require this because code does not fully address surge protection issues.
Ground wire from incoming utility can connect to breaker box ground to meet code. But for surge protection, the earthing system must be enhanced. All earthing wires must run independently and meet at the central earth ground - be it the MGB, bulkhead, earthed structural member, or earth ground rod(s). All utilities must meet at this single point ground to upgrade an 'NEC required' earth ground into an effective surge protection earth ground.
Other limitations. Buried ground wire may be 2 foot deep to meet code. But for surge protection, that wire must also remain below the frost line. Earth ground is non conductive when frozen. Therefore many ring grounds also include 8' earth ground rods to address problems such as deep frozen earth and geology variations.
Sand is also a serious problem for earthing.
Halo or ring ground addresses problems beyond what code requires; especially if in sandy soil. Since we cannot make earth ground conductive enough, then we attempt to make earth under the building "equipotential". But wire is not a conductor to surges. Wire becomes an electronic component. So we also want that ring ground to become the best conductive earth ground in the facility - the 'single point earth ground'. IOW ring ground enhances an NEC required earth ground for two complementary reasons as demonstrated in that previously cited Lem Instrument URL and in a figures from another industry professionals: http://www.erico.com/erico_public/pdf/fep/TechNotes/Tncr002.pdf http://www.xantrex.com/support/docserve.asp?id37 http://www.cinergy.com/surge/ttip08.htm
Mark or Sue wrote:

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Replies are in line.
Mark Wilson wrote:

Once again I have typed too fast. The abbreviation I meant to use is GEC.

That primary telephone protector should be located outside the home. That will keep much of the surge and spike energy outside of your home.

That part of the code CEOs not refer to the Electrical Service GEC but rather to the Communications Grounding Conductor. This conductor bonds the communications protector to the GEC or the other accessible grounding means. W_Tom's suggestion to run the communications grounding conductor to the Ground rod itself will cause a few challenges. One is that conductors smaller than #6 must have protection from physical damage. Lawn mowers, edge trimmers, & weed eaters expose GECs to severe physical damage so any conductor that is run within reach of such equipment must be number four or be run in protective raceway. If the conductors would run adjacent to each other anyway than a split bolt or saddle clamp would be just as effective. -- Tom
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Did the electrician say you need a NEW grounding rod or a SECOND grounding rod? The reason that I am asking is that a local electrical inspector just told me that the "new electrical code" now calls for TWO grounding rods to be installed 6 feet apart -- instead of just one grounding rod. He said one continuous #6 grounding wire would go from one rod to the next rod 6 feet away (and looped around it) and then to the neutral block on the electric panel box.
I know nothing about how all of this works and will probably just have an electrician do it. But, when I saw your subject line, I figured I'd pass on what I was just told in case it helps.
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