Spun Concrete Transmission Poles FAQs | Valmont Utility

Frequently Asked Questions

About Valmont® Utility Spun Concrete Poles


  • Q. Can Valmont Utility make multi-piece poles?
  • A. Yes, Valmont Utility has been making multi-piece concrete poles for years. A typical multi-section pole is comprised of two or more sections joined with our patented tubular steel Splice Joint or bolted flange connection. See Splice Joint Concrete Poles for more information.


  • Q. Does Valmont Utility make wood pole equivalents?
  • A. Yes, Valmont Utility has been providing wood pole equivalents (WPE) since day one. We have WPE designs for both ANSI 05.1 (appendix B) and NESC (ANSI C2-1997) requirements.


  • Q. How do you ground a concrete pole?
  • A. Concrete poles can be grounded externally or internally. External grounding is usually provided by attaching the ground wire to the pole surface using ground clips and cast-in threaded inserts. Internal grounding is usually provided by casting the ground wire into the wall of the pole during fabrication. A threaded "tank ground," also cast into the pole during fabrication, then provides the external connection for hardware attachments.


  • Q. What is a cracking moment?
  • A. Simply put, cracking moment is the bending moment required to induce visible cracking in the outer surface of the concrete. Cracking moment, referred to as Mcr, is a somewhat subjective capacity that must be verified by testing (which Valmont Utility has done extensively).


  • Q. What overload factors should be used for design of spun concrete poles?
  • A. Valmont Utility does not officially endorse or specify any particular overload factors. However, most of our customers use the National Electric Safety Code (NESC C2-1997) as a starting point for their loading criteria. Other guidelines can be found in:




    Minimum Design Loads for Buildings and Other Structures ASCE 7-98

    Structural Standards for Steel Antenna Towers and Antenna Supporting Structures (ANSI/TIA/EIA 222 F 1996) (June 1996)

    Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals (I-LTS-3)

  • Q. How do you field drill a spun concrete pole?
  • A. There are times when a structure may need additional holes after it is received in the field. Field drilling of pre-stressed concrete poles is actually fairly common. The task can be relatively simple and take minimal time provided proper equipment is used. A properly sized rotor hammer drill with a carbide-tipped 4-point masonry bit is used to bore through one wall thickness of the pole. The drill is then repositioned 180 degrees, at the same elevation as the bored hole, to bore the other side of the pole; thus completing the pathway through the pole. If pre-stress strand is encountered, the hole is normally repositioned slightly away from the strand. The spiral wire can easily be drilled through by using the hammer mode on the drill. This process normally takes only a few minutes per side. Proper equipment should be used and aligned properly. Any exposed steel should be cleaned and coated prior to using the field drilled hole. Minor spalling of concrete is acceptable. Recently developed heavy duty core saw bits allow the user to drill through the pre-stressed stranded cable.


 

If you have additional questions not included in this list, please email us at UtilityRFQ@valmont.com.


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