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?

 

[davidbeach]

As opposed to...?

 

[Stillerz]

...as opposed to me detailing out the holes for the the hardware/insulators etc. on fabrication or shop drawing of the pole.

 

[Stillerz]

davidbeach:
These are dodecagonal or 12-sided steel poles anywhere from 45' to 60' tall.

 

[jghrist]

Holes and flanges in steel poles are usually done at the shop before finishing. I'd use flanges for suspension insulator connections instead of holes and eyebolts.

 

[davidbeach]

All that hardware goes onto brackets welded to the poles or on to mounting pads provided with the pole by the manufacturer. Nothing is just drilled into a steel pole.

 

[PHovnanian]

In the rare case in which the structures are wooden, the holes are usually field drilled. As others have stated, for steel structures (or steel components used on wooden or concrete poles) the holes are installed at fabrication.

Often, steel structures will be specified with flanges that have a series of pre-drilled holes for various hardware spacings. Utilities standards departments will have established specifications to suit their construction types. The crews will pick the closest holes that fit conductor elevation and spacings.

 

[dpc]

Don't drill holes in steel poles unless approved by manufacturer.

 

[Stillerz]

thanks fellas....you'll notice the (Structural) next to my name. Apparently the hardware details I have are for wooden poles, not steel, as they should be. If the hardware details are wrong, it means our Electrical engineering consultant has his head buried in his ass.

 

[Stillerz]

dpc:
see my first post...I am detailing and having the poles fabricated...I am the manufacturer.

 

[Stillerz]

By the way...just so i know...
What would be the big deal with using thru-bolted hardware on a steel pole? What are the concerns here?

 

[dpc]

OK -that wasn't clear to me, I guess.

 

[itsmoked]

I would imagine that steel poles are designed with stress reviews and possibly heat treating that can go haywire when you start drilling holes in them. Same as truck frames - you shall not drill them(truck frames).

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Stillerz]

itsmoked:
As the design engineer of the poles I can assure that drilling a several small holes will be of no structural consequence whatsoever. Even holes drilled in very heavily loaded building beams/frames are for the most part totally ignored in the design process so long as they are not drilled in an area of high stress or are unusually large (something other than bolt holes).

 

[itsmoked]

Thanks for the education Stillerz!

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Stillerz]

itsmoked:
Sorry, I wasn't trying to get indignent on you, but it sure as hell sounded that way didn't it!!!

 

[jghrist]

By the way...just so i know...
What would be the big deal with using thru-bolted hardware on a steel pole? What are the concerns here?

Through bolted hardware is OK and is often done with post insulators. It is generally less expensive to fabricate the pole with flanges where appropriate, however, rather than using thru-bolts. Field drilling holes can be done if the finish is repaired, but is more expensive than having the holes drilled by the fabricator before finishing. Repairing the finish with zinc-rich paint is usually acceptable to stop rust, but it if you can predict where holes are needed, have the fabricator drill them.

You might want to include threaded holes for ground connectors if any equipment needs grounding or if the poles need connected to a separate grounding electrode.

 

[Stillerz]

jghrist:

Thank you.
Makes damn good sense.
First good answer.

My main concern was drilling the galvanized pole afterwards and having to make repairs.

The biggest problem I have here is I am a Structural Engr who is designing and detailing the poles (working directly for the owner....everything done in house).
Laying out power transmission lines is not my thing. We have required pole heights, line elevations and hardware details from our Electrical consultant, but i am not comfortable with laying out the hardware locations on the detail drawings. I have completed it, but still dont have much confidence in it. My thinking was that if i left the poles blank I could have the contractor work directly with the Electrical Engr consultant and be sure the hardware locations were correct.

 

[nonsinusoidal]

Practice within your expertise.

 

[jghrist]

I agree with nonsinusoidal. If the electrical consultant will not give you a drawing showing where to drill the holes and install flanges (with hole sizes), then leave it all blank. I would never expect the pole fabricator to determine how to frame the pole.