When installing large cables in an underground duct with bends, which precaution should be taken to ensure a safe installation?

When installing large cables in an underground duct with bends, which precaution should be taken to ensure a safe installation?

• A. Use cable pulling lubricant
• B. Duct should be filled with sand
• C. Cables should be pulled without any lubricant
• D. Use only metal rollers

Answer: (A)

When pulling large cables through an underground duct with bends, the goal is to minimize friction and protect the cable as it moves. A pulling lubricant creates a slick interface between the cable jacket and the duct walls, so the force required to pull the cable is reduced. That means lower pulling tension, which helps prevent damage to the insulation or jacket as the cable negotiates bends and routes through turns. Lubricant also helps the cable glide smoothly around corners and reduces heat buildup from sliding, which can degrade materials over time. Use a lubricant that is approved for cable pulling and compatible with the duct and soil conditions, applying it along the whole run and concentrating on bends where friction is greatest. Filling the duct with sand isn’t appropriate because it can introduce moisture, debris, and future pull obstacles, and it makes maintenance and re-pulling more difficult. Pulling without any lubricant increases wear and the risk of damage. Relying only on metal rollers aids guidance but does not reduce friction or protect the cable, so lubricant remains a necessary precaution.

When pulling large cables through an underground duct with bends, the goal is to minimize friction and protect the cable as it moves. A pulling lubricant creates a slick interface between the cable jacket and the duct walls, so the force required to pull the cable is reduced. That means lower pulling tension, which helps prevent damage to the insulation or jacket as the cable negotiates bends and routes through turns. Lubricant also helps the cable glide smoothly around corners and reduces heat buildup from sliding, which can degrade materials over time. Use a lubricant that is approved for cable pulling and compatible with the duct and soil conditions, applying it along the whole run and concentrating on bends where friction is greatest.

Filling the duct with sand isn’t appropriate because it can introduce moisture, debris, and future pull obstacles, and it makes maintenance and re-pulling more difficult. Pulling without any lubricant increases wear and the risk of damage. Relying only on metal rollers aids guidance but does not reduce friction or protect the cable, so lubricant remains a necessary precaution.