Power/ Utility Pole

[Stillerz]

I am in the process of detailing some power transmission poles that bring power from the road into a substation yard for a new facility. My question is, does the electrical contrator usually field drill the holes in the pole for the connections of insulators and other hardware?

 

[Stillerz]

nonsinusoidal (Electrical) 3 Sep 09 20:33
"Practice within your expertise"

So, designing a pole for line tension loads, ice, wind etc. is not the expertise of a Structural Engineer? Should I consult a "Pole Engineer". Can you do it for me?. I am well within my expertise here and I by no means expect the fabricator to do anything but EXACTLY what I put on the drawing. If my electrical "expert" wasn't a jagoff, I wouldn't have to worry about it. I'd detail the pole showing attachemnt points and have him review it.

 

[jghrist]

I don't think nonsinusoidal was questioning your structural expertise. If you don't have expertise in framing transmission poles (figuring out exactly where to put what), however, you need to get someone who does or leave it up to the field to do.

 

[nonsinusoidal]

Obligation of an Engineer:

"As an engineer, we all shall participate in none but honest enterprises. When needed, our skills and knowledge shall be given without reservation for the public good. In the performance of duty and fidelity to our profession,we shall give the utmost."

I am not questioning your expertise! I was just suggesting for you to exercise what you are an expert at?..........

 

[rterickson]

Typically the Transmission Engineer (could be Electrical, commonly Civil) details how the post insulators, or insulator brackets, or davit arms are attached to the pole. *Somebody* has to be responsible for the design, right?

I've never seen it (the transmission design) left up to the installer, or the pole manufacturer.

Field drilling is common if something like a crossarm for a distribution circuit is attached to the same pole. Even then there should be a design standard, and a work package from the estimator/designer.

What is the transmission voltage for this line?

 

[PHovnanian]

What would be the big deal with using thru-bolted hardware on a steel pole? What are the concerns here?

Do you mean field drilled at some random point through the pole? Now, I'm no structural engineer, but my understanding is that these things are hollow. Just running a bolt through the middle and placing it under tension (dead ending a conductor, for example) and the pole could squash like a beer can.

In my experience, attachment points for significant loads have to be properly reinforced (the odd street light is probably OK). At least that's what my structural people have told me.

 

[MikeDB]

It is a very common practice for steel poles, galvanized or weathering steel, to be field drilled for some or all of the holes. Thru-bolts are the most common type of connection. The design of those connections is often over-looked, which is a mistake. It is generally recommended that holes be drilled in the center of the flats and that flat plate washers, say 4x4x 1/4 or thicker, be used to span the width of the flat. Bolt shear, bearing at the bolt hole, over tightening of bolts and pole crushing due to unbalanced loads are the primary concerns.

ASCE 48-05 is currently under revision with some cautions regarding these issues.