What Is An Arborist Rigging Strap (WLL Specs)
An arborist rigging strap is a rated connector used to attach rigging rope or hardware to a tree or limb during controlled lowering. Its working load limit (WLL) applies only to the configuration stated on its label. There is no universal WLL: check the strap’s identification, condition, hitch method, and compatibility with the complete rigging system before use.
A common misconception is that a strap’s breaking strength tells you how much weight it can safely hold. It does not. Breaking strength describes a test result; WLL is the manufacturer’s stated limit for a defined use. Treating one as the other can create a serious hazard.
I explain the label first because it is the quickest way to avoid guesswork. A strap’s color, width, or sturdy appearance cannot verify its capacity. Nor does the size of a chainsaw or limb tell you whether a strap is suitable. The relevant facts are the strap’s rating, its condition, how it is attached, and the forces the job may create.
Rigging Strap Selection, Equipment Setup & Safety Checks
An arborist rigging strap provides a rated attachment point for a rope or compatible rigging hardware on a tree or limb. Its capacity depends on its material, construction, length, attachment method, connectors, and manufacturer’s instructions. Read its permanent label and verify the planned configuration before it enters a rigging system.
What does WLL mean on a rigging strap?
Working load limit, or WLL, is the maximum working load a manufacturer assigns to a product under specified conditions. It is not the same as the force at which the strap may break. The label’s value applies only to the listed product and configuration, not automatically to every way you might attach it.
Minimum breaking strength, or MBS, describes a minimum strength measured under stated test conditions. It is not an allowable working load. Do not divide MBS by a guessed safety factor to create a field WLL. Follow the manufacturer’s WLL and any applicable standard or job requirements.
There is no single WLL for all arborist rigging straps. Ratings may be listed in pounds, kilonewtons, or both. Check the exact model, label, and instructions; do not transfer a rating from a similar-looking strap or another brand.
Why does the hitch configuration change capacity?
A choker, basket, and straight or eye-to-eye arrangement load a strap in different ways. A manufacturer may rate only some of these configurations, or give a different limit for each. Use the configuration the instructions specify. If a planned hitch is not covered, do not assume it has the same capacity.
Bends, tight turns, sharp edges, abrasion, or incompatible connectors can reduce capacity or damage the strap. A connector must fit the strap as intended and be rated for its role. Do not twist, knot, or route a strap in a way the manufacturer does not allow.
| Check | What to verify | Why it matters |
|---|---|---|
| Product and label | Model, material, readable WLL, and instructions | Confirms what product you have and its rated use |
| Configuration | Choker, basket, or straight arrangement is specifically rated | Different arrangements can change the load on the strap |
| Connectors | Type, rating, fit, and correct orientation | Poor fit or wrong hardware can damage or overload a connection |
| Contact points | No sharp edge, damaging bend, or abrasion | Contact can weaken or cut the strap |
| Whole system | Rope, anchor, strap, connectors, and plan are compatible | A strap rating alone does not establish system capacity |
Before selecting a strap, also consider the tree and planned load. An anchor point must be suitable for the forces expected, and the likely movement of a limb matters. A strap can be correctly rated and still be part of an unsafe setup if the tree, anchor, rope, or connectors cannot handle the job.
Field Rigging and Controlled Limb Lowering
Field rigging means using rope, connectors, and a suitable tree attachment to guide a cut limb down in a controlled way. A sound plan accounts for the anchor, limb, expected movement, and people nearby. The strap’s WLL is only one part of that plan, not a guarantee that the entire setup is safe.
Plan and inspect before installing
Start by setting a drop zone, agreeing on clear signals, and identifying escape routes. Assess the tree and intended anchor for signs of weakness, as well as the limb’s size, position, and likely swing. If any part of the plan is unclear, stop and get qualified help.
Inspect the strap, rope, and connectors before use. Verify each component’s label and intended use, then check that the planned configuration is permitted. Make sure the rope and hardware suit the job and work together as intended. Keep people out of the fall zone and the line of fire, where a moving rope, limb, or failed component could strike them.
Install and lower with control
Place the strap only at the planned anchor. Protect it from sharp edges and abrasion, and attach only compatible, rated hardware. Check that it cannot slide, roll, or load an unintended section of the strap. Follow the manufacturer’s instructions rather than improvising a hitch.
A falling limb can create a force far above its static weight. Static weight is the force from an object resting without movement; a moving or swinging load adds changing forces. If a limb free-falls onto a taut rigging line, that sudden force can damage or break the strap, connector, rope, or anchor. The result may be an uncontrolled fall. Do not treat a WLL as permission to shock-load a rigging system.
Use a qualified crew and a controlled lowering plan. Keep within all manufacturer limits and avoid sudden loading. Stop if the anchor shifts, the strap moves, or the load behaves in an unexpected way. Do not continue just because the strap appears intact.
Illustrative field scenario: I use this kind of example when explaining why a label is only the beginning. Suppose a crew plans to lower a limb from a sound-looking anchor. The strap has a readable rating, but the intended hitch is not one covered by its instructions. The rating cannot be assumed to apply. The crew should choose a configuration the manufacturer rates or select appropriate equipment and revise the plan before cutting.
Another illustrative scenario: If a limb is allowed to drop and suddenly pulls on a taut rope, the strap’s printed WLL does not show that the system can absorb the impact. A safer plan controls the limb’s movement and avoids shock loading. If that cannot be done with confidence, stop and have a qualified arborist assess the work.
Inspection, Cleaning and Retirement Criteria
Inspection means checking the strap and its identification before use, then looking for damage after work. A readable label, sound stitching, and intact material help confirm whether the strap remains usable. Follow the manufacturer’s inspection and retirement rules; do not invent a repair or capacity based on appearance.
Do not use a strap with missing or unreadable identification, visible damage, or a rating or configuration you cannot verify. Look for cuts, heavy abrasion, heat or chemical damage, failed stitching, and damaged hardware. Remove questionable equipment from service instead of trying to estimate how much strength remains.
Follow the manufacturer’s criteria and any applicable standard for deciding whether damage requires retirement. A strap may need to be removed even if damage seems small; the effect depends on its construction and location. Do not sew, splice, or otherwise repair a load-bearing strap unless the manufacturer specifically authorizes that work.
After use, unload the system before disconnecting the strap. Clean and dry it as the manufacturer directs, then check it again for new damage. Record defects or service history when required by the manufacturer, employer, or applicable rules. If in doubt, keep it out of service until a qualified person can assess it.
Storage and Seasonal Care
Good storage helps protect a rigging strap between jobs, but it cannot restore damaged fibers or make an unreadable label acceptable. Clean and dry the strap as its manufacturer directs. Store it away from sunlight, chemicals, moisture, and sharp objects, and keep it where damage can be noticed before use.
Avoid leaving a strap where tools, hardware, or rough surfaces can cut or abrade it. Do not assume that a strap is ready for work simply because it was stored indoors. Inspect it and confirm its label and condition before every use.
If the strap becomes wet, dirty, or exposed to a chemical or heat source, follow the manufacturer’s care instructions and check whether it must be removed from service. Do not guess about exposure effects. When instructions are unavailable or identification cannot be read, do not use it for rigging.
Conclusion and FAQs
The key is to match the strap’s labeled WLL to a manufacturer-approved configuration and use it as part of a compatible, carefully planned system. Inspect the label and condition, control the load, and avoid shock loading. If the rating, condition, or intended use is uncertain, do not use the strap.
What is an arborist rigging strap used for?
It provides a rated attachment point for rigging rope or hardware on a tree or limb during controlled lowering.
What does WLL mean on an arborist strap?
WLL means working load limit: the manufacturer’s stated limit for a defined product and configuration.
Is WLL the same as breaking strength?
No. Breaking strength is not an allowable working load. Use the labeled WLL, not a value estimated from breaking strength.
Do all arborist rigging straps have the same WLL?
No. WLL varies by product and may depend on the attachment configuration. Check the strap’s own label and instructions.
Can I use the strap in a choker hitch?
Only if the manufacturer rates that specific strap for a choker hitch and gives instructions for its use.
Can a cargo tie-down or ratchet strap replace a rigging strap?
No. Do not substitute cargo tie-downs or ratchet straps for arborist rigging components.
Can I use a rigging strap for fall protection?
Not unless it is specifically certified and labeled for that purpose. Rigging use does not establish fall-protection suitability.
Does a strap’s WLL prove the whole rigging system is safe?
No. The anchor, rope, connectors, load, and planned movement must also be suitable.
What should I do if the label is unreadable?
Do not use the strap. Its rating and intended configuration cannot be verified.
What damage means a strap should be taken out of service?
Cuts, abrasion, heat or chemical damage, failed stitching, and damaged hardware require attention under the maker’s criteria. If in doubt, remove it from service.
(This article was written by one of our staff writers, Evan Bradley. Visit our Meet the Team page.)
