The four basic rules of rigging apply to every lift, regardless of size or complexity:
Know the load weight. Determine the exact weight and center of gravity before selecting equipment or rigging hardware. Under OSHA 1926 Subpart CC, the operator must not exceed the equipment’s rated capacity, which requires knowing the load weight before any pick. Estimating by eye is the single most common cause of overload failures.
Inspect all equipment before use. Per OSHA 1926.251, a competent person must inspect every sling, shackle, hook, and connection point prior to use on each shift. Look for broken wires, stretched links, cracked hooks, and missing or illegible load tags. Defective gear comes out of service immediately.
Never exceed rated capacity. Every piece of rigging hardware has a working load limit (WLL) forged or stamped on its body (slings carry attached load tags). That limit assumes a straight vertical pull — sling angles reduce effective capacity significantly. At a 60-degree angle from horizontal, a sling retains only about 87% of its rated capacity. At 30 degrees, roughly 50%.
Use the correct hitch configuration. Vertical, choker, and basket hitches each change how force is distributed. A choker hitch at a favorable choke angle (greater than 120°) retains about 75% of the vertical hitch rating — and drops further at tighter choke angles per ASME B30.9 rated capacity tables. A basket hitch can double the vertical rating, but only if the D/d ratio and sling angles are maintained. Match the hitch to the load geometry and the rigging plan.
These four rules are the foundation of ASME B30.9 and B30.5 compliance. Skipping any one of them puts the load, the equipment, and the crew at risk.
Planning a lift that needs professional rigging? Get a quote from our vetted contractors.