Understanding NEW SRL Classifications and Leading Edge Hazards
Recent updates to the ANSI/ASSP Z359.14 standard have simplified how Self-Retracting Lifelines (SRLs)
are classified. Using the wrong SRL for a specific application can result in a catastrophic equipment failure during a fall.
Understanding the difference between these two classes—and specifically understanding Leading Edge
(LE) hazards—is critical for ensuring everyone goes home safely.
The Core Difference: Anchorage Location
The new classifications are built around one primary factor: Where is the anchorage point located
relative to the worker’s dorsal (back) D-ring?
Class 1 SRLs: Overhead Only
• Anchorage Location: Must be anchored at or above the worker’s dorsal D-ring.
• Clearance: Designed to arrest a fall within a maximum free-fall distance of 2 feet.
• The Rule: NEVER use a Class 1 SRL for a leading edge application or tie off below the D-ring. If a
worker falls over an edge with a Class 1 SRL, the cable or webbing is highly likely to sever, and
the internal shock absorber is not rated for the increased forces.
Class 2 SRLs: Leading Edge & Foot-Level Tie-Off
• Anchorage Location: Can be anchored above, at, or up to 5 feet below the worker’s dorsal D
ring.
• Clearance: Rated to handle a free-fall distance of up to 6 feet over a structural edge.
• The Rule: If there is any possibility that the lifeline will come into contact with a sharp or
structural edge during a fall, a Class 2 SRL is legally and practically required.
What is a Leading Edge (LE)?
A “leading edge” is the unprotected side and edge of a floor, roof, or formwork that changes location as
additional sections are constructed.
If a worker is tied off at foot-level and falls off the edge of a concrete slab or steel deck, the lifeline will
be pulled tight and bent at a sharp 90-degree angle over that edge under immense force.
Why Class 2 is Required for Leading Edges
Standard Class 1 SRLs are not built to survive the physics of a leading edge fall. We mandate Class 2 SRLs
in these applications for three life-saving reasons:
1. Shear Resistance: Class 2 lifelines are constructed with larger diameter, reinforced materials
(often specialized galvanized or stainless steel cable) tested against sharpened steel edges to
ensure they will not sever or fray when dragged across concrete or steel under the weight of a
falling worker.
2. Energy Absorber Placement: In a leading edge fall, the lifeline above the edge might get locked
in place while the worker continues to fall. Class 2 SRLs feature an integrated energy absorber at
the worker’s end of the lifeline (right at the D-ring) to ensure the shock-absorbing deployment
actually protects the worker’s body, rather than being trapped up at the housing block.
3. Increased Force Tolerances: Falling over an edge generates significant pendulum and cutting
forces. Class 2 blocks are engineered to arrest heavier loads dropping further distances while
maintaining the structural integrity of the line.
Summary for the Field
• Working directly under your anchor point? Class 1 is safe and compliant.
• Tying off at foot level? You need a Class 2.
• Working near an unprotected roof, deck, or slab edge? You need a Class 2.
When in doubt, default to a Class 2 SRL. It provides a wider range of safe working conditions and is the
only acceptable choice when edges are involved.
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