Rigging: specific terminology

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02

August

2016

Rigging is anything that is suspended during the build-up process of stages. It is based on the use of safety cables, chain hoists, electrical chain hoists and trussing structures, among other elements, to fly lighting systems, sound equipment, LED screens, etc.

 

Before talking about the most common elements of rigging, which we will explain little by little on our blog, first of all we are going to define some words used in the entertainment industry, because knowing their meanings is essential.

 


Rigging

Installation, removal or other activity using lifting or suspension equipment and/or accessories to raise or support stages, trade fairs, performances or technical events. (UNE-CWA 15902 part 2).


Competent person

Person with enough theoretical and practical knowledge as well as experience with such task, and aware of his knowledge limits, experience and competence. (UNE-CWA 15902 part 2).


Rigger

Competent person who is capable to carry out rigging jobs. (UNE-CWA 15902 part 2).


Head Rigger

Rigging’s team leader (UNE-CWA 15902 part 2).


D:d

Spin relation between the diameter of an object or a pulley (D) and the cable or string (d) which leans or goes through it.


Safety factor

It is the ratio of the breaking load and the partial force when the load acts (UNE-CWA 15902 Part 1). In other words, it is the relation between the minimum breaking load guaranteed by the manufacturer who has an equipment or an accessory and the maximum working load given by the manufacturer.


M.B.S.

Minimum breaking load for any equipment, accessory or piece, guaranteed by the manufacturer.


Safety point

Redundant security which takes action in case of a failure of the main system. The safety point must be tightened as much as possible for working with guarantee and avoiding that load might descend a long distance accumulating energy with the result of generating a greater load shock from the initial weight it had. More than 5-10 centimeters is not a safe option.


Working Limit Load W.L.L.

Maximum working load given by the manufacturer for an equipment. All equipment used for rigging and under the Machinery Directive must be marked with the W.L.L. among other data.


Uniform loads

Uniform distributed loads (UDL) are loads distributed throughout a vain with the same value and weight along it. For example, lights distributed throughout a truss.

UDL load in one side of the vain is called concentrated load and is calculated as a Center Punctual Load (CPL) applied in the center of its position.


Fixed point loads

Loads that are located in one point and weigh 100kg or more, for example a moving head.
 

Cantilever loads

Loads applied on a part of an overhung truss with a single support (electrical chain hoist, truss leg) on one side.
 

External loads

They are loads that we do not control and are acting on our trusses. These loads must take into consideration, for example meteorological factors such as rain, snow or especially wind.
 

 

We will talk more about rigging, legal and utilization issues, work equipments, load types, maintenance, inspections, etc in future news. Stay tuned to our blog because we still have much to tell you!

 

Bibliography: AFIAL. Beginner's Guide to Rigging in the entertainment industry. Pablo Moreno