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With an 8' extension
& bit, this Rock Drill
would have done it
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The system
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Before anything else: bury a grounding rod 8'
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7 shots: hammering the rod 42" into sandstone
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Only 54" to go; this jackhammer will get it ...
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Nada! There is something very solid at 42"
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(This added 7 months later ...)
(The Rehabilitation Hospital of the Cape and Islands)
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Need 96" to be legal so starting a 2nd rod
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This one stops at 35" - still need another 19"
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(Physical therapist Pam Roesch retraining my neck)
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Our 'grey water' may help rod 3 go down
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It made it to 47". That should do it!
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Cut rod 3 below grade to avoid tripping on it
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Cut rod 2 below grade
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Cut rod 1 above grade, kinda
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The equipment ground exits the building
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The wire will pass through clamps on all 3 rods
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These 3 shots, taken a year later, show the vertical ground wire going up to the rails
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The wire is run from rod 2
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Through a trench towards rod 3
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Buried & soaked with grey water
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The wire terminates at rod 3
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Rods 2 and 3 are covered to protect feet
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The trench between rods 2 & 3 is filled
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The idea, I'm told, is to run one single heavy guage copper wire from the equipment down to a copper clad steel rod buried 8 feet deep in moist earth.
Inside, my 1/4" thick #2 wire runs from the
combiner box down through the
charge controller box through the
DC breaker box passing the
inverter, down through a hole in the floor and out to rod 1. There it joins a 1/8" #8 wire coming down from the
mounting rails on the roof. It passes through a clamp on that rod and then out to a clamp on rod 2. A #8 wire goes on to a clamp at rod 3. The 3 rods are in series, one after the other. All wire beyond rod 1 is buried 3 to 12" deep.
There must be no branching either from separate equipment, or to separate rods (in parallel). The lightning bolt needs to find one clear path down into the earth. If it finds more then one it may try to arc between them causing one heck of an expensive show instead of just going quietly away.
I am somewhat concerned about whether or not the lightning bolt will find this earth attractive at all - it is way too dry. At least where it ends at the 3rd rod, my sink water often overflows the bucket and spills out. Hopefully the earth at that point will be somewhat damp below grade - at least better then anywhere else that I can think of. Hey, my inverter likes it.
Some suggest periodically sprinkling epsom salts where the ground is too dry. I have not done that but I have been dumping my coffee grounds there and I flood the trenches (slowly) with grey water when the bucket fills up. However, I think my triple rod and long wire approach should carry the load.
One additional note is that the rods should be at least 6 feet apart. Apparently if they are closer together they can cause radio interference. Though I and my neighbors may not be radio buffs I might be inclined to extend that to interference with wireless routers, which I do use. That is pure guesswork but why take the chance. Anyhow maybe somebody around here might get into radio one day.
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The lugs must fit tight, biting into the rails
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They will end up under the PV modules
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The wire runs from the rails down to rod 1
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A solid copper 'Ground Bushing Lug' was provided with each mounting rail. For some reason the lugs did not include bolts so I got those locally. They have to get a good tight grip. That lightning bolt will need a clear solid path to ground so I don't want any whimpy connections causing resistance. I lightly roughened each surface with sandpaper to improve contact and remove any potential oxidation. I wanted as large a bolt as could fit through the lug and the top track of the rail so that they could be tightened hard without breaking. The head of the bolt being slid into the track still would not get a good enough contact so I included a washer with it. The washer was too wide for the track so I nipped the edges off to make them fit. This plus double-nutting got a good tight fit that will not loosen over time.
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Inside, the ground begins at the combiner box
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It travels down through the charge controller
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From the controller it passes the DC breaker
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It passes by the inverter and the battery bank
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It exits the building and heads to rod 1
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I used the heavy 1/4" #2 wire initially because I wanted to be sure (and because I wasn't sure). That, I realize now, was overkill. That costly 1/4" wire was difficult to manipulate around corners and through boxes. The 1/8" #8 wire that I used outside would have been more than adequate for the whole thing.
I do have one thin ground from the inverter clamped to the big #2 wire passing by. That could be called a 'branch' (well, twig). I hope that won't be a problem but without that little green wire the inverter blows its fuses (yes, I tried it). Then where the heavy #2 wire from the equipment joins the #8 wire from the roof at rod 1, we have 'branching', I think. I hope the lightning bolt will find the thicker #2 wire heading south through the earth to be more attractive, if not the rod itself.
National Electrical Code
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Have since learned
that had I used a
'Ground Rod Driver'
bit on a clean rod,
it might have worked.
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