# E-stop code requirements?



## z2oo (May 27, 2022)

Hey folks, I'm curious to know if there are any U.S. codes that require motorized theatrical equipment to have an E-stop, or if it's "best practice" at best? I've found some guidelines that mention them, but nothing concrete or lawfully required yet looking at OSHA, ISO, etc. I'm specifically looking to put some weight behind the argument of needing to add an E-stop to a roll drop assembly (large projection screen) that doesn't have a way to stop travel once in motion. It's large, moves very quickly, and also can be activated from an iPad on the _building's_ WiFi system--so in theory 5 floors away without eyes in the room.

My hope is to find some supporting documentation to back up the need for a new control system that can solve the E-stop and iPad control issues. And a motor/VFD replacement in future for the speed.

Thoughts?


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## MRW Lights (May 27, 2022)

Before we sound the alarm bells over ethics... let's get some more information. 

Is this an actual Projection Screen System or a custom build? I ask because typically the manufacturers of these types of automated systems don't allow for free fall, they also have built in safety mechanisms similar to the brakes on an elevator as well as tension limits so that if tension releases beyond a certain limit based on the calibrated wieght of the screen it also stops the unit. What is the rate of travel of this screen and does it have an audible signal when lowering/raising, these are options available from some manufacturers.

You may be fighting an unnecessary battle that has been solved by manufacturing and installation. Though it also places trust and life safety on robots which isn't always my preferred method without a backup, but that being said these systems are typically reliable...


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## RonHebbard (May 27, 2022)

azylka said:


> Hey folks, I'm curious to know if there are any U.S. codes that require motorized theatrical equipment to have an E-stop, or if it's "best practice" at best? I've found some guidelines that mention them, but nothing concrete or lawfully required yet looking at OSHA, ISO, etc. I'm specifically looking to put some weight behind the argument of needing to add an E-stop to a roll drop assembly (large projection screen) that doesn't have a way to stop travel once in motion. It's large, moves very quickly, and also can be activated from an iPad on the _building's_ WiFi system--so in theory 5 floors away without eyes in the room.
> 
> My hope is to find some supporting documentation to back up the need for a new control system that can solve the E-stop and iPad control issues. And a motor/VFD replacement in future for the speed.
> 
> Thoughts?


 *@azylka * Be certain to include an adequately rated, spring applied, mechanical brake. If / when your E-Stop simply removes the motor's power, gravity may force it to continue to unwind. Gravity; it's a law, not just a theory.
Toodleoo! 
Ron Hebbard


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## egilson1 (May 27, 2022)

The ESTA ansi standards for hoists, motorized rigging, and automation all have e-stop requirements. 

Downloadable for free here.




TSP

The ESTA Technical Standards Program (TSP) is an American National Standards Institute (ANSI) accredited program established with the purpose of helping establish industry standards for the entertainment industry. The program consists of the Technical Standards Council and several specialized...


tsp.esta.org


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## Ben Stiegler (May 28, 2022)

perhaps you could alter the interface so that it requires continous button press on the down button for travel, vs. trigger. and if theres a camera in the room, make pressing the down button automatically turn on sufficient light and activate a medium-res stream of that camera to the iPad that initiated the motion.


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## RonaldBeal (May 28, 2022)

Not aware of a specific code per se, BUT (and there is always a big "but") it does fall under OSHAs general duty of care.
You have identified a hazard... now that hazard must be removed or mitigated. A "deadman" switch may mitigate that hazard sufficiently, or a warning klaxon with delay, and proper (documented) training may mitigate that hazard... Ultimately it comes down to the totality of the circumstances and hazard mitigation.


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## MNicolai (May 29, 2022)

Ben Stiegler said:


> perhaps you could alter the interface so that it requires continous button press on the down button for travel, vs. trigger. and if theres a camera in the room, make pressing the down button automatically turn on sufficient light and activate a medium-res stream of that camera to the iPad that initiated the motion.


We've done this before. Requires a continuous button press to keep the keep the screen moving. Also requires programming and a controller to do it, since the low-voltage controller in most screen systems is _not_ ordinarily designed for this. Basically, as soon as you release the up/down buttons, the control script sends a STOP command. Usually don't do it on simple projection screens but I've been involved in a few large-scale gym divider systems that are effectively the same thing but they drop all the way to floor, and those systems also have control of the basketball backstops. So an inattentive operator could get into some trouble if they just hit GO and walk away.

I have the same question as @MRW Lights, standard projection screen or something custom? You say it moves _very quickly, _which would be unusual for the average projection screen.


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