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Potential Safety Hazard Alert

Chris Higgs of the National Rigging Advisory Group has recently written the following notes on the POTENTIAL safety hazards arising from the use of certain new moving lights…

In the same way as we would all regard the dangers of using pyro near our rigging, we should all be aware of the potential dangers in using rigging close to some of the newer automated lighting fixtures that have appeared recently.

Their ability to project very narrow beams of light is the problem. Concentrating light and thus heat onto a very small area is akin to using a magnifying glass to start a fire on a sunny day. Already we have seen photos online where one brand has allegedly melted a chain-motor chain bag from some distance. One manufacturer states 18m distance should be allowed between the lens and an object the beam might strike. Chain bags, scenic elements, props, soft goods and even costumes are presumably also at risk of catching fire in this way.

No reason to over-react, but we should raise awareness of the potential hazards. The use of such luminaires and the effects they can create is not in question. It is the bigger picture we need to consider; the safe use we make of pyrotechnics is a good analogy.

Risk assessment is the key. A lighting designer may not be able to avoid the beams hitting objects during programing. Fixtures that break down may be left shining on objects, errant cues, the list goes on. If there are such moving lights on a show you are rigging, consider the risks of the beams hitting man-made fibres and other rigging equipment. Polyester slings (on trusses or roof beams) could be melted through very quickly.

Non-combustible methods of suspension should be used if there is a risk. Truss pick-up beams, steel wire rope slings that do not rely on ferrules to hold the eye termination (ferrules can lose their grip as they expand with heat) and chain slings (Grade 80 or 100 short link sling chain) may be solutions. Check the manufacturer’s recommendations of all the components used with regard to high temperature.

Since there is still a school of thought that suggests simply ‘backing up with steel’ is the solution to man-made fibre sling failure, please remember that any secondary suspension (‘safety’) should be rigged as if it were a primary (properly slung, not choked on one chord of a truss), be of sufficient quality and strength and crucially, not slack. If a polyester fibre sling fails and drops a load into 60cms (2 feet) of slack, the force generated can be as much as 10 times the load the sling originally carried.