Class III rigging dictates that the minimum level of responsibility is a competent rigger communicating with a qualified person and the qualified person may communicate with a qualified engineer. The responsibility includes rigging plans for Class I, II or IV construction. According to ANSI 10.48, a “Qualified Person” is one who can develop rigging plans and who has successfully demonstrated the ability to coordinate construction related to the wireless industry.
The ANSI 10.48 Competent Rigger/Qualified Person responsibility is to develop a rigging plan, but for Kathy Gill, President and Owner of Tower Safety, the question is: does the Qualified Person understand the block and tag line angles that can create enough force to cause drop loads or a fatality? “A rigging plan is required for every lift at a site and a Qualified Person needs to understand the math that is creating forces on every lift,” Gill said.
But first, one needs to know the definitions:
- Force is a push or pull upon an object resulting from the object’s interaction with another object. Whenever there is an interaction between two objects, there is a force upon each of the objects. Forces only exist because of an interaction.
- Newton – Force is a quantity that is measured using the standard metric unit known as the Newton. One Newton is the amount of force required to give a 1-kg mass an acceleration of 1 meter per second squared (m/s/s). 1 Newton = 1 kg • m/s2
These invisible forces of gravity, friction, air resistance, tension, and spring create enough to damage equipment, hurt or kill someone. Gill said her company, Tower Safety, has put together a video to help understand block and tag line angle forces varying on the type of structure, location of pulleys and the tag person. “The ability to imagine right angles that do not physically exist when rigging to solve Pythagoras theorem is the key to a successful lift,” she said.
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