What Are Pulling Irons and Why Are They Required in Concrete Manholes?

If you've ever tried to pull cable through a duct with nothing solid to rig against, you already know why pulling irons exist. A pulling iron is a heavy steel loop or U-shaped bar cast into the wall or floor of a concrete manhole or utility vault, providing your crew with a fixed anchor point to pull against. When a winch or block and tackle puts thousands of pounds of tension on a conductor, that force has to load onto something that will not budge. The pulling iron is what the rigging hooks to.

Here's the catch: You cannot add a proper anchor once the concrete has cured. A manhole wall is smooth and reinforced, with no built-in point strong enough to take a full-tension pull. The anchor has to be set while the structure is still being formed, so precast manufacturers and utilities call out pulling irons as part of the pour rather than leaving it for the field crew to sort out later.

Underground runs between manholes commonly reach 100 to 150 feet, and long or curved runs build friction fast. Pulling large conductors or innerduct through that distance can take several thousand pounds of force. This isn't the place to improvise. Federal and utility specifications put hard numbers on it. The Unified Facilities Guide Specifications tell crews to install a pulling-in iron in the wall opposite each duct line entrance, and many utility standards rate that iron for 10,000 pounds of pulling tension.

The iron sits on the wall directly across from the duct, so the pulling line runs straight into the conduit mouth. That straight shot keeps the sheave or quadrant block in line and level with the duct, protecting the cable from sharp bends and maintaining consistent tension throughout the pull. 

When an iron is missing or doesn't line up, crews end up fighting the job with temporary rigging, such as a jamb skid braced against the opening. It works in a pinch, but it eats setup time and rarely holds up like a cast-in anchor on a heavy pull.

A pulling iron lives in a wet, corrosive spot for the entire life of the manhole, so material choice is a real part of the spec. Hot-dip galvanized steel is the workhorse, coated to ASTM A123 for long-term corrosion resistance. At Valley Nut & Bolt, our pulling irons are cold-bent and stress-relieved before galvanizing, so the finished part holds its rated strength. Where conditions are harsher or where an owner would rather avoid fighting coating wear over decades of service, stainless steel is the better choice.

Traceability matters just as much as the metal. Every part we make ties back to batch numbers and quality control data, exactly what public agencies want as proof of what went into the ground. That's why our pulling irons are American-made and QPL-certified by the Washington State DOT. On DOT and municipal jobs, that documentation is often what closes out the submittal. Get the anchor right at the manufacturing stage, and you keep your crew safe and your cable pull on schedule years down the line.