Tower inspections

[calchuck]

I am just about to finish my first wind gen and have the stater cast and in the process of painting. I was able to find a Tri-Ex HS 588 tower. It was an original 58 foot three section tower but the top section was missing and I was able to pick it up for $50. While inspecting a neighbors new steel building, the County building inspector came over and asked me what I planed to do with the tower. When I told him, he said they didn't have a problem with the generator because it was only 48v but I would have to have an engineering report saying the tower was useable for the purpose. I am not able to find any information about these towers and wondering if anyone has used one. Also, I am wondering what other people use for towers when they have to be inspected? I would be willing to change to a pipe mast but I don't think they will allow it either without and engineer. Does anyone know if pipe masts have been engineered and if the report is available? RE is great if the government dosen't get in the way.

[Phssthpok]

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Karl Tashjian

I worked at Tri-Ex Tower Corporation from 1985 to 2000. While at Tri-Ex, I was the engineer of record for hundreds of towers. While at Tri-Ex, I worked on tower designs for the amateur radio, cellular, FM, TV, AM radio, and the US Army.

In 1997, International Tower was formed from Tri-Ex Towers and S&G Communication. ITI specialized in tall towers for the broadcast industry. While at ITI, the engineering group which I was in charge of engineering and designed several candelabrum towers approximately 2,000 feet tall, 1860' tower 10' face tower in Louisiana, a 1,000 foot tall candelabrum in downtown Atlanta guyed at 35%, along with many other tall heavy towers.

In January of 2000, SpectraSite Broadcast group purchased International Tower Inc. SpectraSite closed the engineering offices at the Tri-Ex plant in Visalia in October of 2000, at which time I began consulting full time.   The old Tri-Ex Towers Corp. was dissolved in California so I incorporated as Tri-Ex Towers Corp. in California in Jan. 2002.  In Jan. 2003, I changed the name of the corporation to Tashjian Towers Corporation.

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Quoted from the page found at the following link:

http://www.tashtowers.com/info.html

Hope that gives you a direction to continue your investigations!

[stephent]

Well, the tower would certainly more then likely support the weight of the genny ok, but the usual stick in the spokes of the use of a triangular (or 4 legged)  tower for a wind genny is the "wind loading" limit they have. (10 ft diameter blade set=78 sq foot wind load--more/less and ice will add hundreds of pounds and more wind area)

You might try registering here... http://lists.contesting.com/mailman/listinfo/Towertalk

and ask if anyone knows specs for your tower. If any hams have used one or have one, hams are notorious for keeping installation and manuals for any and all equipment they have..good for future reference, etc. And they like to share knowledge also.

Give a short descripion of what you are trying to do, as many will be interested in RE sources for feild day use. (extra points for off grid power).

Getting an engineer to do a re-certification of an old tower for intended use will be difficult without him/her actually looking at the tower and inspecting welds, condition, etc.

Look up inside the lowest section of the tubes--if there's any rust showing--good luck.

It would be easy to sell that tower to a ham probably for enough $$ to build one with pipe sections--but then your still stuck with an engineering study and certification for it as well.

Sometimes there's a small loophole in the permit/inspect govt thing--some towers under xx feet won't have to have those "certifications", depending on locality...ya might want to go see and ask since they already know ya have it and are planning to use it.

 

[Ungrounded Lightning Rod]

Sometimes there's a small loophole in the permit/inspect govt thing--some towers under xx feet won't have to have those "certifications", depending on locality...ya might want to go see and ask since they already know ya have it and are planning to use it.

You might also ask him if the requirements are lower if you position it so that, if it falls, it (and any snapped guy wires) won't hit anything - structures, parking areas, playground areas, neighbor's land - and put a fence around it to mark the "don't be here if it's windy" area.  B-)

[calchuck]

Thanks for the responces. I live in the SouthWest corner of Arizona and it has never snowed here in recorded history. It rains about three times a year and very seldem gets below 40 degrees. I did go down to the County office and talked to the head inspector and he said they want an engineering report for what ever tower I put up in what ever location. I planed on guying this tower with three guys at every 20 feet but that didn't phase him at all. I understand that pipe towers would have less wind load but I would still need the paper. Too bad there isn't a common design pipe tower that one could get paper for. CHUCK

[elt]

10 ft diameter blade set=78 sq foot wind load [...]

Is that right? It doesn't seen right to me. I picture the blades not turning, just three sticks up in the air. I don't think they'd have a 78 sq foot wind load but I don't really have a clue how wind load is calculated ... I would have guessed that it was slightly less than the actual front profile area of the wood (or whatever), not the swept area of the blade.

- Ed.

[RP]

When its spinning it behaves like a solid disk in terms of wind load.  Hence radius squared X PI.

[Rewop Emoh]

I'm no pro but I think according to Betz' Law you would have to factor that by 59%.

[DanG]

Has any private citizens there legally erected a tower, ever?

Can you find out what has been acceptable & duplicate that, or piggy-back on some existing installation's engineering report by installing a clone of it?

[Countryboy]

Government workers ALWAYS want you to file paperwork with them, and pay any fees they can invent.

Tell the County worker who says that you need an engineering report that you want him to show you whatever relevant ordinance or law requires you to provide him an engineering report.

Odds are, he can't come up with a law that applies to you.

Please note, you will need to read the definitions they provide for all legal terms in that code section.  Many times, the lawmakers will invent some weird definition to a common word, which changes the meaning entirely.  For example, the IRS has some funky definitions for the word 'wages' - and unless you are a government worker, you probably don't earn any money that meets their definition of wages.  However, if you claim to have received wages, they will gladly tax you on them - they have no problem with you paying a tax you don't really owe.

On it's face, the law may appear to apply to you - until you read the definitions and see the words do not mean what you thought they meant originally.

[Countryboy]

Be especially sure to read the definition of a tower.  It wouldn't surprise me if a tower was a vertical structure owned or operated by some sort of utility/telecom company.  Or, a tower may need to be a minimum number of feet tall before it is classified as a tower.

If you are not a utility company, or your tower is shorter then the minimum - that law won't apply to you.

[jmk]

 If you can find a friend with a engineer stamp maybe you could draw the tower and he can stamp it. I have had friends around here that have done that before. The Inspector, as stated above has to give you a code refference number so you can comply with that code. Alot of inspectors make their own stuff up which holds nothing if there isn't a code in writing. We get stingy with some of the building inspectors when they are wrong. You must be polite. They are just like a police officer if you happen to hit one. So don't get crapy with them. Just let them know you want to read the code that they are pretaining to and what is the code number. Then read it.  

[elt]

At first, that didn't seem right to me... imagine a motor turning the prop at exactly the the TSR so that (perfect) blades were carving through the air at same speed as the wind... the blades would be "invisible" to the wind the and the wind would exert no pressure on them. Well, there'd still be the force on of the wind on the size of the static profile.

It's written that the blades work by slowing down the wind, by taking energy from the wind. So I GOOGLEd for wind pressure and load, found the formulas for wind pressure per square foot, got the right conversion calculators and, sure enough, the radius-squared windloading, give or take the Betz limit and a little bit or so comes up with the watts number (more or less) that we expect to see out of a mill...

But wait! Those watts are going down the wire. The same energy can't both be going down the wire and be trying to break my tower in half.

So given the "motor driven prop" thought experiment and the that the energy is going down the wire, not bending the tower, I'm back to not seeing that the wind load is the same as the swept area...

 - Ed.

[RP]

That's a good point and now I'm thinking about this too.

Let me add this thought.  In the event of an electrical failure (blown rectifiers, burned stator, etc.) no power will be extracted so more (most?) of the energy will be bending the tower.