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Over 2,000 years ago, when Jesus carried out His ministry around Galilee, He often spoke to his followers out in the open with nothing but the heavens above them.
In the 21st century, churches attract thousands of followers under one roof, usually with sophisticated sound, lighting and video systems. The result is tons of heavy equipment suspended over the heads of the congregation creating a huge safety challenge.
Jesus said, “Build your house on a rock.” (Matthew 7:24) and thus, following this edict, every church needs its structures to be as if “built on a rock” – incorporating every safety feature available via modern technology to completely protect those in attendance and preventing catastrophes that can be caused by dangerous overloads.
All lifted loads should be monitored
Overloads can occur even when the most seasoned riggers are involved. Load distribution on trusses is unpredictable. The benchmark is that all lifted loads must be monitored.
But, if I know the weight of each speaker, light and video wall, isn't that enough to prevent overload? Unfortunately not. The problem is not only the total weight of the suspended load but the distribution and possible redistribution of that load. Whenever there are more than two hoists on a truss or more than three hoists in a structure, it becomes statically indeterminate, resulting in an unpredictable load distribution. In most cases this will cause a load imbalance, in which some of the hoists may reach overload while others carry only a small part of the load. This is an undesirable and unsafe situation that might result in dangerous overload.
Continuous load monitoring enables immediate detection and correction in real-time on site, resulting in danger safely averted. In fact, load monitoring of suspended loads is so vital that it will soon become part of an internationally recognized safety standard for all large audience sectors.
The solution
The solution is an advanced real-time multi-point load monitoring and overload prevention system, preferably wireless, in which load cells are installed on the hanging points and transmit via radio frequency to a radio receiver for continuous monitoring. The best systems incorporate software that provides simple integration with the rigging plan, and enables overlay of the load map right onto the rigging plan on screen, making it easy to see where motors and loads are situated. This enables the rigger to immediately identify the location of a potential overload and take swift preventative action. It is also advisable for the system to have a built-in set point option emitting an overload/under-load alarm (both visual and audible) that automatically prompts a motor to stop in case of an overload.
The more hanging points with a load cell installed the safer the entire installation. Although you can start off small and expand over time, the ideal for maximum safety is to reach a load cell on each and every hanging point.
So what would the most optimal load monitoring system include?
There are several crucial elements of a safe load monitoring system that every rigger should be aware of, but which not all systems include. One of the most important is continuous 24/7 monitoring of a load, which is critical in preventing overload accidents. Continuous load monitoring enables uninterrupted active monitoring from setup to tear down and does not include potential safety traps like sleep or stand-by modes. Non-continuous monitoring with sleep or stand-by modes is not acceptable from a safety perspective as load reporting should never be passive. For example, if a dangerous overload occurs between reports while in passive mode, no alarm is activated and the consequences could be disastrous. There is also the real possibility that the system will not wake up.
Another important factor is power. Load monitoring systems should never be turned off after load distribution has been verified as several scenarios could occur that could lead to a dangerous situation. If additional equipment is hung at a later stage or if a lifting device or suspension point fails hours after the rigging has been completed, the change will not be recognized by the system with potentially tragic results. The solution is a load monitoring system with an independent power supply, one that allows for continuous monitoring of loads even after power has been shut off. A reliable battery is a must as well and a long battery life is optimal. Battery life should be long enough to enable continuous load monitoring from setup to tear down, even in long productions, which means thousands of hours of battery life.
Like many other ancillary devices, load monitoring systems can be wired or wireless. Wireless load monitoring systems have several advantages over wired systems. Besides the fact that a wireless system makes for a faster and more convenient setup, a wireless system with less cable mess is better at handling dynamic applications where the load cells are in movement.
Because large-scale venues like mega churches often need dozens, possibly hundreds of load cells and tend to continuously expand their systems, a good load monitoring system ought to be able to handle several hundred load cells and have a long transmission range, preferably with the ability to add an unlimited number of extensions to cover even the largest projects. For the highest level of safety the load cell system should have an extremely high accuracy rating, as precise as ±0.1%.
A high quality load monitoring system should have real-time load mapping as standard. This enables the rigger to quickly identify potential overloads and take swift preventive action. Another useful tool is data logging, which creates a report of the load distribution and is important after the project for post-show analysis.
Load cells should be extremely durable and an ideal load monitoring system should have the flexibility to handle a load capacity of well over 100 tons. The safest load cells are made of high-strength steel of aerospace quality and should be fatigue-rated, a measurement of the load cell's ability to withstand successive load cycles for unlimited periods of time without the risk of failure or damage to the steel. For use in highly humid or rainy conditions, a high IP rating of 65, 67 or 68-1 is necessary depending on the application.
Additional safety features should include independent data flow and multi-channel transmission, as well as an internal safety check that ensures the displayed data is always an exact match with that being transmitted by the load cells. Functions like Bluetooth compatibility with smartphones and tablets is a useful benefit as well as is convenient communication like real-time SMS alerts, which provide an added layer of supervision.
That's a lot to ask of one system but when you're dealing with increasingly heavy and dynamic loads suspended above audiences and performers, the greatest of care should be taken and the standard set high. A review of the various options available for load monitoring reveals an excellent example of a system that fulfils that high standard, the Ron StageMaster, designed and manufactured by Eilon Engineering, a company that, interestingly, is located in the Holy Land, on Mount Carmel.
