I'd like to add a quality grounding rod to my house. I know from prior research, that ground water exists from maybe 12 to 17 feet below ground, below which is hardpan. It seems that a 17 foot ground rod would give me the best ground, but
10 feet seems to the the longest I can find. Are there longer ground rods available? Where? Is my reasoning "reasonable"?bob
research, that ground water exists from maybe 12
rod would give me the best ground, but
available? Where? Is my reasoning
Bob
How would you drive in a rod that is 17 feet long? It's a bitch driving in a 10 footer at times. You got to get on a ladder and then the think likes to bounce around as you sledge hammer it down.
10ft. is plenty, and in most areas, the NEC requires at least 2 rods spaced at least 10 ft apart, then bonded together.I am not saying you can not or should not use a longer rod, but it's not needed and would be a pain to drive in. Actually, you could take an 8 foot piece of galvanized pipe, put a cap on the end, drive it in, and attach another 8 footer with a coupler. If you are lucky, the threads on the first piece will survive. I am not sure if the NEC approves pipe, but I have used it on the farm for electric fences and it works as good as anything else.
Of course you could weld some rods together too.... Just weld a piece of pipe across the ends, but good luck hammering it in.
It would make more sense to couple two rods somehow. Drive one in, put on the coupling, then the second rod.
I imagine they don't make extra long ones because they are not needed, not practical.
Utilities buy "screw-in" ground rods that are driven in with a gas-powered tool and have a cast screw on the end that goes in the ground. Some of these can be "extended" to your desired 17 feet. But these rods are not cheap (hundreds of dollars) and the tools are exquisitely specialized.
Unless you are having trouble getting the low-resistance-to-ground that the NEC requires (which might be the case if you live on the side of a mountain for example) such measures are usually not necessary. If you're as close to the water table as you claim then the two code-required 8 foot/10foot rods are probably pretty good for most purposes.
Plain old water pipe can be driven down (and extended) more easily than ground rods to your desired 17-foot distance. Depending on what your inspector says you will probably need the two code-compliant (shorter) grounding electrodes too.
They make sectional ground rods; the ends are threaded (including the pointy end), and thet have special couplers and a driving stud so you don't bugger the threads when you pound on them.
But last time I checked, 3/4" (or larger) galvanized water pipe or RMC is NEC approved for use as a made electrode, and can be had in 20' lengths without needing a coupling. I would drive it using a ladder and a T-post driver rather than a sledgehammer.
Best regards, Bob
research, that ground water exists from maybe 12
ground rod would give me the best ground, but
available? Where? Is my reasoning
google is your friend
quality grounding rod?
I know of no study that has found that getting a ground rod into the water table is worth the effort. Sure would be hard for us folks in the SW deserts.
Placement of the "supplemental ground rod" should be outside the sphere of the primary grounding system. Amec makes a meter that can measure ohms/volts to ground with out interruption.
I measured my last house and found that the installed ufer ground was less than 10 ohms. Not much reason to spend the effort in setting another ground in that situation. That was done on a dry July morning.
The "low-resistance-to-ground that the NEC requires" for ground rods is
25 ohms, which is a joke. I would rather use a 16 foot ground rod than 2 8' rods because it would get into other soil types and get closer to wet soil. Also, I presume the top of a ground rod is ineffective in the winter in the frost belt.I think (not sure) rods with threaded ends, as described by Bob, used to be around - havn't looked recently.
Also think (not sure) I have seen attachments for some of the larger hammer drills that are for driving ground rods.
bud--
Thanks everyone. It sounds like the galvanized pipe solution will be the easiest solution for this problem. My soil is a fine sand below about 2 feet, so driving the rod should be no problem. I can push a "normal" rod down 4 or more feet by hand.
Would it be fair to assume that if I combine multiple rods that they should all be galvanized if any one is? In other words, I shouldn'd mix galvanized and copper plated rods?
Bob
research, that ground water exists from maybe 12
ground rod would give me the best ground, but
available? Where? Is my reasoning
Go to
copper is pretty much incompatible with almost all common metals except passivated stainless steel and lead. Iron and zinc are both prone to galvanic reactions when in contact with copper. In short - no don't mix copper plated with other types.
A threaded 3/4" grounding rod is around $25 for 10 feet, including the pointed end. Couplings are around $8. Not as beefy as what the utilities use, but how many amps do you plan to dump down a household ground rod?
From the picture and the text that device is only measuring current. Its somehow calculating resistance based on that - I cant imagine it being anywhere's near accurate. If it were that simple you could use your clampon ammeter and a table. Eric
easiest solution for this problem. My soil is a
push a "normal" rod down 4 or more feet by
be galvanized if any one is? In other
Don't mix them. If you use galv pipe and use a regular rod, use a galv rod. Otherwise you may get premature failure from corrosion.
Yeah, but who has all these meters and stuff, Aside from the electric company and some of the large electricians?
Unless you install ground rods on a daily basis, it's cheaper to just install the 2 rods specified in the NEC, and be done with it. You can never "over ground". In fact 3 or 4 rods are even better. On my garage, there are 2 rods, plus I ran a wire over to one of the pieces of large angle iron buried in the ground from an old steel windmill. The windmill is long gone, but these steel legs stuck out of the ground and constantly tripped me. I finally put my stick welder on full power and burned off 3 of them under the surface of the ground. I dont know how deep they go, but my tractor loader would not budge them. The 4th one I left as a ground., and placed a t-post next to it so I dont trip over it.
How do you suppose ohmmeters work? The caculation is done by the mechanism in mechanical meters, but all they do is measure amperage, which they do by measuring voltage drop. Everything is calculated from voltage drop, mechanically or electronically.
If it were that simple you could use your clampon
If your clampon is accurate.
Remove NOPSAM to email me. Please let me know if you have posted also.
Or a 5A fuse...
Best regards, Bob
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