On 11/9/2013 5:47 PM, Jim Lux wrote:
On 11/9/13 9:28 AM, Michael Tope wrote:
Thanks, Jim:
Both AB Chance-Hubbell and MacLean Power Systems sell them for utility
applications:
http://www.hubbellpowersystems.com/anchoring/expanding/
http://www.macleanpower.com/products/item.asp?ITEM_ID=2087
Except for the W8JI site, I have never seen any mention of them as an
option for ham radio towers.
I noticed that one of the entries in the table you linked to showed a
depth of 73ft! I can't imagine that would be the requirement to get a
good anchor, so perhaps that's how deep they had to go to get into the
soil conditions that are listed.
yeah, that's weird.. Maybe it's because "dig a hole and fill it with
concrete" is something one can do with pick and shovel and little
training.
Driving the real deal anchors 20 feet in with hydraulics is a
specialized operation. Most structural engineers know about these
things, so if a ham was in a situation where they were talking to a
PE, and the screw in anchor was appropriate, they'd mention it.
They're used a LOT for utility poles, which often have enormous side
loads. The same hydraulic rig that runs the auger for the pole can be
used to drive the anchor.
When I lived just South of Breckenridge MI. the HV line ran E/W across
the fields. The distribution line ran under it Ours was about the 3rd
tap on a line that must have been 12 miles or more. From that line to
the pole at the edge of our lot was a "maximum span" and that was one
honkin big screw anchor back guying the power pole. I think it was
around 1976 when we had the big ice storm.
To the West of us there was over half a mile of distribution line flat
on the ground with the poles snapped off. There was close to 3" of ice
(total 6" diameter) on these lines. They didn't stand a chance. It
pulled that big anchor to the point that I expected the pole to break,
but it didn't. OTOH that line came across the field at less than 3 feet
off the ground and the pole looked like a bow at full draw.
I had never seen power lines close to 6" in diameter from ice and have
never since, either.
We were close to two weeks with out power, but had a big fireplace and a
miniature fireplace (barbecue) in the kitchen.
I thought that at least we're going to have hot food, that is, until I
fired up the barbecue. I threw the pan out in the snow. Both flues were
full of ice.
I never lost an antenna, but the ends of the elements on the big KLM
monobanders were pointing nearly straight down.
73
Roger (K8RI)
When I was in the EFX business, there were two companies in the LA
area who essentially did ALL of this kind of work for everyone.
Boudreaux or something like that. You'd tell them the pull out load
you needed, and they'd show up with their truck and drive the anchors
(e.g. for our 50 foot high tornado rig out on Ave E in the high desert)
I don't know about the 70 foot depth. I know they've had terrible
times with the anchors for the retaining walls on the 405 widening
project in Sepulveda Pass. They're over 100 feet deep, and still
pulling out. I think those are "bore hole, insert anchor, then grout"
type anchors. The "rock" there is just not very "rock like" (and it's
water saturated.. there are artesian springs everywhere
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