Overhead power lines are susceptible to storm damage and require continuous maintenance from “tree topping” to pole maintenance and replacement. Underground power lines, protected by HDPE conduit, are gaining popularity with utilities. Furthermore, underground power lines improve curb appeal and make neighborhoods more aesthetically pleasing.

HDPE conduit has long been used by state highway departments for traffic signal and highway lighting applications. Additionally, fiber optic cable is installed in the same conduit trench for ITS (Intelligent Transportation Systems) to monitor traffic, provide automatic toll payment, and CCTV systems to monitor accidents and provide safe motoring.

Although direct bury power cable systems are designed for long life, use of HDPE conduit to encase and protect the power cable from rock impingement is prudent engineering as it allows for quick and easy repairs without excavation of the cable. HDPE conduit and innerduct is used to carry low (600V-transformer to end user) and medium ( < 35kV-substation to transformer) voltage power lines.

BDI HDPE conduit is shipped on reels owned by BDI. When a reel is empty, BDI will pick up it up at its own expense.

HDPE benefits include:

  • A wide temperature range for installation, from -20 degrees C to 90 degree C operating temperature for cables
  • A low coefficient of friction (20% lower than PVC) to allow for long cable pulls
  • Tough, durable and a life expectancy well over that of the power cable.
  • Replace or repair cable lines without digging or trenching
  • Chemical and corrosion resistance
  • Easy installation, HDPE pipe is the preferred material for HDD (Horizontal Directional Drilling), because of its long continuous lengths and high pull strength
  • HDD benefits include the elimination of traffic disruption and minimal surface damage
  • Can be continuously plowed as opposed to trenching PVC sticks.

HDPE Standards and Dimensions

Smooth Wall Duct

Smooth Wall HDPE Duct is the industry standard for easy blowing and pulling of cable due to its low friction walls.

Smooth wall is the industry standard High Density Polyethylene (HDPE) duct available from Blue Diamond in ½” through 6” in a variety of wall thicknesses and colors. Standard colors for the power and utility industry are red, or black with three red stripes. The interior of smooth wall has a slick finish which delivers a low coefficient of friction allowing long power cable pulls. It can also be pre-lubricated at our factory. Cable in Conduit (CIC) means power cables can be installed in our manufacturing facility during our extrusion process, saving money by eliminating the need for pulling cable in the field. It also insures a clean pathway from the factory to the field.

Ribbed Wall Duct

Blue Diamond's Ribbed Wall Duct is designed for extremely long cable pulls. Ribbed Wall innerduct is internally ribbed.

Blue Diamonds ribbed wall conduit and innerduct is designed to allow extremely long pulls of cable by lowering the coefficient of friction. Lubrication of the conduit is standard on CIC applications.

UL Listed Duct

Blue Diamond is also UL (Underwriters Laboratory) listed for power applications. BDI UL duct meets UL 651A Continuous Length HDPE Conduit and BDI is listed under UL 1990, Nonmetallic Underground Conduit with Conductors. UL 1990 is the specification for UL power cable in UL conduit-CIC. UL listed HDPE is compliant with Article 353 of the 2011 NEC NFPA 70 National Electric Code and NEMA (National Electrical Manufacturers Association) TC 7, Smooth-Wall Coilable Electrical Polyethylene Conduit.

UL Listed HDPE conduit is available in EPEC-40 (Schedule 40) and EPEC-80 (Schedule 80) wall thicknesses from ½” through 6”. It is also available from Blue Diamond in EPEC-B (SDR 13.5 wall thickness) in 1 ¼” through 6”.

UL listed conduit from Blue Diamond has a high tensile strength to weight ratio, superior crush resistance and a low coefficient of friction which makes it ideal for HDD (Horizontal Directional Drilling).

  • Note: Engineers and contractors often specify a heavier, SDR 11 wall thickness for directional drilling. UL does not recognize SDR 11 in its specifications. If you require a more robust conduit for tough field conditions, BDI recommends specifying UL EPEC-80 (schedule 80) in diameters ½” though 4”. Schedule 80 matches up well with SDR 11 wall thickness through those diameters. Above 4”, SDR 13.5 UL listed pipe is the heaviest wall available.
    • Consult the BDI spec sheets.
    • UL Listed and NEMA Conduit is not available in ribbed inner wall. UL and NEMA conduit only provide for smooth wall pipe.

CIC Fill Ratio Worksheet