What’s the Best Way to Lubricate Cable When Installing into Conduit or Duct?

Lubricants are essential for underground cable installations to reduce friction, enable longer pulls, and protect cables from damage.

The goal of any application technique is to ensure that the lubricant gets between the cable and conduit surfaces in contact. Ideally, this happens by applying an even coating of lubricant along the length of the cable and conduit surfaces. Simple logic would dictate that the bigger the cable installation, the more lubricant is required. While it is important to know how much lubricant is required for a cable pull, “more” isn’t always the answer to reduce friction and lower cable tension. In fact, the more pertinent question is, how should the lubricant be applied to effectively optimize cable lubrication?

To answer that question, let us first examine a couple of common lubricant application techniques by illustrating methodologies employed by two different installation teams. While these teams are fictitious, their lubrication techniques are based on real-world examples that are currently part of installation practices today.

To keep the scenarios analogous and simple, both teams specialize in installing cables into underground ducts. They are pulling a single conductor horizontally into a single duct for a length of approximately 1,312 yards (1,200 meters), with a path that has several bends. Both teams are also using the same type of specialized, high-performance, liquid cable lubricant.

Cable Installation Team A: The Manual (Hand) Method

Team A has tried a few different cable lubrication techniques over the years but has landed on the Manual Method as the best approach for this type of installation. This is partly due to their specialist, Chuck. While Chuck is the guy to lubricate the cable, there is definitely no one else on the installation team who would want to do his job. That is because Chuck gets his hands coated in lubricant when manually lubricating the cable. Chuck has been lubricating cables by hand for over 5 years and is quite capable. His technique has proven that this is the best way to do it for his team.

To begin lubrication, Chuck positions himself on a small stool seated about a meter away from the conduit opening, right where the cable is entering the duct. This proximity is primarily for safety reasons. Chuck does not want to get his hands too close to the conduit opening where he could accidentally get injured while he is lubricating the moving cable. But he is close enough to the lead end of the cable to properly apply lubricant. In this stationary position, Chuck scoops up a generous handful of lubricant from a nearby 5-gallon (18 liter) pail and slops it onto the surface of the cable. He uses both of his gloved hands to spread the lubricant pile around the circumference of the cable jacket—making certain that each cable section that passes him is evenly coated before reaching back into the bucket for another portion. He repeats this process until the cable has been pulled all the way through the duct.

Chuck’s technique makes certain the cable is consistently and evenly coated with lubricant before entering the conduit. But there is an additional benefit to his method. While Chuck is lubricating the cable, he is also inspecting the cable jacket surface for any defects, abrasions, or scuffs that may have occurred. In this way Chuck is not only the “lubricant guy”, but he is also a quality assurance specialist. The team installs the cable with confidence knowing that the entire cable surface area has been examined. The Manual Method, or hand lubricant application technique, could be a messy process with the inexperienced worker, but the simple placement of a tarp or mat underneath the lubrication point contains spills to make both the clean-up easy and the site safe from potential slip and fall injuries.

Cable Installation Team B: The Pour Method

Team B has tried the Manual Method for cable lubricant application but has found success in the Pour Method, where cable lubricant is drizzled onto the cable jacket surface before it is pulled into the duct. While anyone on the team could perform this task, there is one guy who is well suited for it. His name is Daryl, but everyone calls him Lou. He is the go-to cable lubricant technician on his undergrounding team, and every job depends on him. Lou possesses diligence and a steady stout frame to make the Pour Method successful.

Lou stands in a stationary position, 3-6 feet (1-2 meters) away from the conduit opening, at a perpendicular angle to the cable being pulled into the duct. Using a 2.5-gallon (9.6 liter) jug he carefully pours the lubricant at a generous but steady rate in a zig-zag pattern across the top surface of the cable jacket. With the help of gravity, the lubricant flows down the sides of the cable and finally to the bottom side before entering the duct. As part of the Pour Method, gaps in lubricant coverage can occur at application. Eventually, these gaps will be minimized when the surface areas of the cable and conduit interface inside the duct. The constant application of a generous quantity of lubricant is necessary to accommodate these gaps in coverage. The specialized lubricant is viscous enough to cling to the cable jacket surface during the pull and allow it to be spread. Lou especially likes this technique in chilly weather, as he can keep his warm work gloves on while he pours lubricant.

Similar to the Manual Method, the job site can become messy if measures are not taken to place a tarp or mat underneath the lubricant application point. But Lou is a professional and keeps his workspace tidy and safe.

For smaller diameter horizontal cable pulls, Lou modifies his pouring technique, but it is essentially the same method. However, for vertical cable installations, the Pour Method is implemented differently. In these types of cable installations, Lou pours the lubricant directly down the conduit mouth onto the interface of the cable and duct interior wall. Gravity also plays a vital role in moving the lubricant into the conduit. Depending on the situation, a different specialized lubricant is used for this type of installation.

Although both Chuck and Lou bring distinct techniques and expertise to their roles, the effectiveness of their methods depends on how well the lubricant reaches its critical destination—the interface between the cable and conduit surfaces. This raises the question: “Which team truly has the upper hand when it comes to cable lubrication?”

Which Team is more effective at cable lubrication based on their application technique?

The short answer: The use of any specialized, high-performance cable lubricant is beneficial to the installation and longevity of the cable. The most critical part of any lubricant application method is to deliver lubricant to where it is needed most: between the cable and conduit surfaces. While this is straightforward at the point where the cable is entering the duct, it becomes more challenging the further the cable travels into the conduit and where it encounters bends in the conduit path. Let us examine how each of the previously explored application techniques are effective.

In the Manual Method, Chuck from Team A spread the lubricant around the entire circumference of the cable jacket using both hands. While it is possible that he may have missed a few spots along the way, he was liberal with his lubricant application. This created an even coating, or thickness, of lubricant across the cable’s surface. Regardless of the conduit pathway, any contact between the cable jacket surface and the inner wall of the duct should encounter some amount of lubricant with this application method. This will ensure that any friction forces are reduced and tension on the cable is eased. Manually applied lubrication is a common technique for effective and safe cable pulling if the technician is consistent and applies plenty of lubricant throughout the pull.

The Pour Method used by Lou on Team B can yield more random results than the Manual Method. Yet, Lou was pouring a specialized, high-performance cable lubricant and was experienced in his technique. As long as plenty of lubricant was used to allow the lubricant to flow around the cable before going into the duct, this technique should coat enough of the cable to lower tension.

Advancements in Cable Lubricant Application Methods

The Manual and Pour Methods for cable lubricant application are historically the most common techniques used in electrical and communications cable and wire installations. This is likely because they are the oldest application techniques, and they are practical, not requiring additional equipment. As new types of cable pulling lubricants emerged in the 1970s replacing things like soaps, greases, oils, and bentonite clay slurry, the opportunity to advance how lubricants were applied soon followed. Over the past 50 years, innovations like gel lubricants have improved manual application techniques, and advancements in liquid polymer-based lubricants have enhanced pourable lubrication. In more recent years, technological advancements have driven emerging application techniques. It is hard to say definitively if specialized lubricant formulations created opportunities for new application modalities or vice versa. Yet, newer delivery mechanisms have become part of today’s cable lubricant application techniques. These methodologies are:

Spraying

An advanced thin-film liquid lubricant is sprayed into the duct using a spray bottle in smaller cable installations and an industrial sprayer for larger installations. This technique is typically applied to smaller diameter cable installations. Another variation of spray delivery lubricants is the spray foam types. These spray foam lubricants are packaged in small aerosol canisters and made for premises wiring installations into small diameter conduits.

Pumping

Pumping can provide consistent lubricant application, less waste, and a safe, clean working environment. Pumping lubricant can also free up labor normally required for Manual and Pour Method lubricant applications. Advancements in mechanical pump technology have produced more compact and portable equipment. This has furthered the practice of automating cable lubrication in the field. Today, there are many diverse types of pumps on the market, which have placed an emphasis on pairing the right type of equipment with the best lubricant formulation. For more information on cable lubricant pumping, read the Polywater Guide to Cable Lubricant Pumping.

Prelubrication

For larger, complex, underground, electrical cable installations, an application technique was developed by Polywater to help maximize friction reduction, optimize pull length, reduce damage, and increase installation success. This is the concept of prelubrication, which involves lubricating the inner walls of the duct ahead of the cable pull. Different lubricant delivery mechanisms can be used to accomplish conduit prelubrication. One delivery mechanism is Front End Packs (FEP). These are conduit-sized bags of specialized lubricant that are attached to the winch line and can be pulled far into ducts that are <5 inches (12 centimeters) in diameter. FEPs help deliver the lubricant to areas where lubrication may be inadequate, such as in the bends. Mandrels and foam spreaders can also be used to accomplish prelubrication by carrying the lubricant deep into the duct, spreading a thin layer of lubricant throughout the conduit length.

The introduction of fiber optic cable blowing technology in the communications industry introduced a specialized lubricant formula from Polywater. This lubricant was specifically made for this technology to safely increase the distance and length that fiber optic cable can be installed.

The True Measure of Cable Lubrication Success

Whether you are a “Chuck” or “Lou,” the success of a cable installation does not hinge on your specific lubricant application technique. Truly the best way to lubricate the cable during an installation is any method that adequately transports the lubricant between the cable and conduit surfaces. This is essential to lower tensions and enable safe cable installations.

With the wide variety of cable lubricants available—each designed for specific installation conditions and techniques—selecting the right product is essential. By collaborating with Polywater, engineers and installers can confidently choose the optimal lubricant and application method tailored to their unique project needs. This approach ensures safer and more efficient installations that protect critical infrastructure for the long term.

Key Takeaways:

• Cable Lubricant Application Techniques: The lubricant application technique is only as important as the lubricant placement. The cable and conduit surfaces that are in contact must have lubricant to ensure an optimal installation.
• Cable Lubricant Selection Matters: Cable lubrication technique is intrinsically linked to the lubricant type. The use of specialized high-performance cable lubricants is an essential ingredient to successful cable installations and cable lubrication technique.
• Common Cable Lubrication Techniques: Common methods like the Manual (Hand) and Pour Methods are effective but require proper execution to ensure consistent lubricant coverage along the cable.
• Technologies Enhance Application: Advanced techniques, such as spraying, pumping, and prelubrication, can provide alternative options for cleaner, more efficient, and automated solutions for cable lubricant application.
• Other Contributing Factors to Cable Installation Success: Efficiency and safety are priorities. Proper lubricant selection and application technique not only reduce cable tension and installation challenges but also ensure a safe and tidy work environment.
• Collaborating with Experts: Polywater is a manufacturer focused on successful customer outcomes. We welcome field involvement and collaboration to ensure optimal results of cable-in-duct installations. Reach out to Polywater for your next cable installation project.

Have any questions?

For help in selecting the right cable lubrication and application technique for your next cable installation project, contact Polywater: Email Us