[TowerTalk] Grounding tower
grants2 at pacbell.net
Sun Jan 5 10:11:35 EST 2014
Ground the anchor bolts to the main rebar cage with several short pieces
of rebar, tied tightly. You might consider tack welding if you have
followed the recent thread on that! My HDX589 bolts were tied together
at two levels with #3 rebar tacked on while the bolts were snug on the
base. Then the base was removed and the bolt cage set inside the main
cage and tied together. Makes it easier to pour and finish the concrete.
You will have over 150 sq ft of concrete in contact with earth and the
concrete bottom of 20 sq ft or so is 8 ft down. Every 5/8" x 8 ft rod
driven full depth is 1.5 sq ft of surface. CA is a very low lightning
frequency state, so I wouldn't bother with more rods. I lived on a
ridge 1500' above SiVly for 18 years and never saw a ground strike on
that ridge. When I lived in eastern MA, the lightning could be really
The "flash and fracture" is urban legend IMO, particularly if the rebar
is assembled to code. Check the codes for explosives, munitions, and
flammable liquids storage facilities - all REQUIRE Ufers.
Enjoy your new tower!
On 1/4/2014 5:42 PM, Mike Fahmie wrote:
> I'm putting up a HDX572. Digging the hole has been quite a job, hardpan was encounter a few feet below the surface and it was alternating jackhammer and backhoe work for two days to get close to the specified depth.
> Now, I'm wondering if I'll be able to drive ground rods into that stuff! I have a impact driver with the appropriate driver head but I need a 'Plan B' if, as I expect, the rods won't go in. I can imbed some rods or heavy gauge wire into the concrete (ala Ufer ground) but have heard that if the tower takes a strike the moisture in the concrete could flash into steam and fracture the concrete.
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