Thursday, July 03, 2008

III. Tree House, From the Bottom Up

Part III

Once the boys had the base standing suitably, with the first three horizontal support tiers and all respective stiffening cross pieces installed and tightened, it was time to position it. Eddy asked me where I wanted it, not only the spot on which to place it, but how I wanted it arranged in respect to the trees and the porch. I figured the best way to decide this was to climb inside, stand directly in the middle and look straight up. Doing this, I pointed in one direction then another while calling out for them to move it a few inches this way and that, as well as having them turn it on its axis so that the largest tree limbs would not have to be cut back. My goal was to adjust it so that once the tower was raised to full height it would poke straight through the middle of the three trees and into the sky.

In less than a minute or two I had it exactly like I wanted it. I extricated myself to have a look at the result, curious to see how it would look from the porch entrance. With only a slight adjustment more I was satisfied. The stairway entrance would be in an ideal spot, and the tower base was still set so that the eventual topside would poke through the tree branches unencumbered.

After that, I ran out of money. I needed another week or so to wait for a check to clear in my local dollar account before we could proceed. The banks here rip you off in almost every way to include what should be the simple function of transferring money into local accounts from stateside ones. We normal “little people,” those without the necessary connections and clout, have to write checks and then wait for about a month for the money to “clear.” In reality, the money “is there” almost immediately, taking no more than a day or two for the electronic transfer to take place, but the bank holds on to it for weeks to use as they see fit. Sigh. It’s just one more of the many little (and not so little) inconveniences foreigners have to put up with for the privilege of living in “paradise.”

The next step was to provide a robust foundation. I sure would hate to be standing on the platform some 45 feet up only to have a strong gust of wind topple the whole thing over. I could just imagine what it would look like; probably like a tall tree falling after a lumberjack had his way with it. “TIM-BERRRRR!” No thanks. We made sure it was “set in stone,” so to speak.

Eddy marked the exact spot where all four supports would stand, had the tower base moved out of the way and then had two of his lads dig a squared off pit at each of the carefully marked spots where the four legs would ultimately stand.

At the same time he had the other two of his progeny cutting round bar into a host of separate pieces to weld up a cage of metal destined to be set into the concrete that would be poured into each of the four 3 feet deep pits. It seemed to me that he was over-engineering it, but I that was fine by me!

When I came home that afternoon he had all four foundation cages completed with one already in its pit and ready for immersion in concrete. I was impressed at the thought that went into the design of the cages. Each was wide at the bottom with its own base; rising up from that base a rectangular column of long threaded bolts poking through and in turn were welded to a base plate designed to sit directly atop the concrete. The four primary vertical support legs would then be welded to these

I never did get to see them cement the cages into place. By the time I got back the next afternoon all four were already in the ground and curing. Things were moving steadily along, just as they always do when Eddy “The Man” is in charge of a project!


Ed said...

I've wired money from here to a dollar account in the Philippines and it gets there almost instantly. However if I remember right, I thought the fee for the honor of doing so was pretty steep for me.

I'm guessing where you live doesn't have any zoning laws. I can imagine the ruckus my neighbor the lawn nazi would raise if I built a tower like yours in my lawn. I would be in front of the city council before I could even climb the stairs the first time.

Anonymous said...

I see your tower every day I come inside the subdivision. It looks cool but I have one fear...


What's it going to be like during the next lightning storm?

On Iwo Jima we had a bad lightning storm one night. I could stand in the doorway and see the lightning hit our 1,350ft tower.
1,2,3,4,5,6,7,8,9,10,11,12,13,14 then all hell broke loose. The klaxon alarms went off, but not in the normal way. They used to go on and off, this time they went steady.

The next hit took out our power system.

Lightning is a funny thing. Every strike was like water going into a bucket (the bucket being the ground plane). Our problem was that the bucket over filled that night.

The water (electrons...i.e. lots of them) spilled {splashed} over the buckets edge. Now that the ground plane was saturated the lightning jumped over any path it could find to any other ground source. It was like water randomly splashing out of a bucket. Stray electrons were going anywhere and everywhere.

The lightning jumped from the transmitter ground plane to the signal power ground plane, via the wires we use to send the signals to the transmitters.

Our electricity jumped from 120VAC at the socket to a little over 300VAC (because the online generator voltage regulator had failed). All our lights got very bright and started popping. It burned out our fire alarm system that ran between between the signal power building and the barracks. The lightning had now filled up two ground planes and was now jumping to the third.

The lightning burned our just about anything plugged into power sockets.

My transmitters faired very well despite the loss of primary power for cooling. It was months before everything else was back in order.

I just want to remind you that you now have one big lightning rod right next to your house. Lightning will hit your tower because of its height. Your problem will be getting rid of all that raw power as it floats through your tree house's ground plane.

Your neighbors might complain if the lightning jumps to their house (ground plane). Make sure no one in your house is anywhere near water or anywhere near the tree house when the lightning strikes. If you see a lightning flash and hear its thunder in less than four seconds than it is close enough to hit your tree house.

The guards at the security gate may have quite a show to watch. To be honest with you I would not want to be anywhere near your house when this happens.

I hope this never happens. But lightning is status quo were we live and your tree house sticks right up there like one big lightning rod. I would suggest you take precautions lightning is lethal and I fear it will be all over your house once your tree house ground plane has saturated and from what I see you don't have much of a ground plane so it will saturate fast. It will be just like water splashing from an overfilled bucket. Except in this case your house is very close to that bucket. And your house is not protected for this type of situation.

Our buildings in Iwo Jima were built to sustain lightning, yet we still sustained damage (no loss of life). This was a rogue storm and Iwo Jima has little land mass to create lightning storms. But we live in the middle of Pampanga with a large land mass. This land mass that protects us from Typhoons generates lightning every major storm.

Be careful, be safe...

PhilippinesPhil said...

Okay, I'll stay out of it during lightning. Sounds like excellent advise.

Anonymous said...

I've been thinking and did some research.

When lightning strikes your tree house you will have what is commonly called ground potential rise (GPR). The electricity will dissipate into the ground. People have been killed standing near a tree struck with lightning because of the GPR. If one foot is nearer the tree house and the other is say a foot away, the electrical potential between the two feet is enough to cause current to flow from one foot to the other resulting in possible death.

When I used the term bucket you could think of a glass filled with water and your house as another cup setting lower. As long as you don't place a straw between the two you should be ok. And what I mean by straw, is anything that can conduct electricity. Once you do this then the lightning will jump to the other glass.

Just make sure nothing touches your tree house (like the tree in your lanai) and then touches your house. The lightning will then jump from the tree house, wreck havoc on your tree, and then to jump to your house. A rain soaked tree makes a mighty good conductor of electricity.

You also can't bring electrical power to the tree house without providing a path for lightning to get into your house. The lightning will jump across the wires and wreck havoc inside your house.

When I first saw your tree house I thought it would be cool to have a remotely controlled camera but that camera must be isolated. You could create the isolation via fiber optic but the camera would still need isolated power source to run and fiber optic could be expensive. We used to provide power to our tower lights (FAA requirements) via isolation transformers. Our towers were isolated via oil filled insulators but lightning still hit them. We just provided an inch and three quarter air gap for the lightning to jump across at the Z-feed point, the feed line turned ninety degrees and the air gap was straight to ground. Lightning does not like making sharp turns so in theory it will always jumps the air gap rather than make a ninety degree turn. This is what protected our transmitters.

The GPR from the Lightning will slowly drop over time. You are going to have to make sure your tree house and its resulting GPR are isolated from anything near your house so that it can't jump. If there is a path the GPR from the lightning will find it and wreck havoc.

All in all, it will be quite interesting...but extremely dangerous. If you keep the GPR from the tree house isolated then your tree house will actually act as an umbrella for any lightning. The lightning will always hit the tree house before it will hit one of your trees or your house.

Power companies in the US do this by suspending a ground wire from pole to pole that is a couple feet higher the than other three wires. Each pole has a ground wire that is attached to it and a wire that runs down the pole to a ground rod. This keeps the lightning out of the power system by acting as an electrical umbrella. Unfortunately they don't do that here and that is one reason we have so many power failures during lightning storms.

Good luck my friend...

KA said...

You know, everything you're building really makes me envious.