Do stack lights make the most sense for my assembly line?

Which signaling devices make the most sense in a varied and sometimes harsh environment?

A Control Design reader writes: I have a problem, and it may be the stack lights. I'm designing the control system for a large multi-station assembly line in an automotive application. In previous projects, I mounted stack lights and alarm annunciation directly to the main control enclosures and connected digital I/O. Unfortunately, this wasn’t always the best location, and the devices were poorly sealed.

What are some better options for mounting, operating and acknowledging system status and signaling devices? The stack lights will need up to five colors and need to include an audible alarm. These signaling devices must be able to handle a harsh industrial environment and the mounting location varies.

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  • My best results were to mount them "upside" down from a box in the ceiling. They were out of the washdown area and it makes them visible to the operators from a long distance without causing an interference.


  • Dear Reader, Stack lights are still one of the best options available for assembly line signaling, in any environment. By nature, stack lights are a great choice due to their modular design, 360 degrees line of sight, and ability to include an audible alarm. These features make stack lights ideal for signaling operators over a larger area. Key features to look for when specifying stack lights are the UL listing and CE mark, the ability to meet the UL Type 4/4X rating, as well as the use of high quality raw materials. Because the environments and locations for the stack lights can vary greatly, choosing a stack light solution that can stack up to 5 modules high, has multiple base mounting options and an adjustable volume on the audible alarm will also be beneficial. To learn more about c3controls stack lights, visit John Berenbrok Product Manager c3controls


  • Not sure if you are looking for mounting options or alternatives to your existing stack-light system. There are several alternative solutions to standard stack lights. Intelligent LED tower light systems- fully assembled sealed devices from various manufacturers are available with and without the audible/alarm system. Some of these devices are fully programmable in your controls system for light colors, intensity and mode of operations. They can be mounted with various mounting options near the action- they do not have to be mounted to the controls enclosure. The Balluff SmartLight may be a good solution. Please find more details at


  • It's helpful to consider the operators location when integrating visual lighting- operators aren't always in front of a console or HMI. They may be somewhere else on the line, loading material, setting up the next job or whatever. A Stack Light's goal is to gain an operators immediate attention providing direction on what to do next (ie, Yellow Flashing might mean there is a warning somewhere and they'd best go look at the HMI to see what is specifically). Operators are easily trained to interact with machines based on the color coded feedback of a stacklight- easier so than using large HMI screens. Just my observation, but operators tend to use the Stacklight as a first-line-of-defense for action on a machine. This often justifies their use (small print disclaimer, yes... my company manufactures indicator light products as well as integrates them). An indicators mounting location, however, is important and should take into account where the operator might be up and down the machine work area so they can see it. Units with Buzzers help! Hope this helps, best of luck with your project.


  • Banner Engineering has standard offerings that can solve all of these challenging applications. Banner's new modular stack light model TL70 has a IP65 rating specifically designed for harsh industrial applications. Banner's iconic stack light model TL50 has an even higher IP67 rating for more demanding applications. Both models are designed for and tested in high shock and vibration environments. It can be difficult to decide where to locate stack lights. Visibility and the availability of power and data are always a concern. To address these challenges Banner offers a wide variety of mounting solutions. Many different brackets are available for both the TL50 and TL70 models, including sealed brackets, elevated mounting systems and adjustable arms. The availability of data and control can sometimes be the largest challenge. Banner now offers a wireless version of our TL70. The wireless TL70 has a wireless radio built into the base of the stack light that can communication with any Banner wireless network. You can now control the segments on the stack light with no direct control inputs to the light! In addition to being robust enough to survive harsh industrial environments Banner stack lights offer a wide variety of options. The TL50 has a number of different styles with ten different colors and three different audible tone options with the ability to have up to seven segments in a single stack. The modular TL70 offers five different colors and two audible options with the ability to have up to six segments in a single stack. With our easy to use online configurator you can custom design the exact stack light you need for your application. - Matt Hahn, Technical Marketing Engineer – Lighting, Banner Engineering


  • Siemens offers a wide range of stack lights. The 8WD44 series with 70 mm diameter makes it possible to mount up to five elements. If you wish to mount an acoustic element, than up to four light elements are mountable. A fast and flexible connection is possible due to spring-type terminals. Furthermore the integrated degree of protection IP65 enables handling of harsh industrial environment. Juergen Duemmler, Product Marketing Manager


  • The location and placement of a light tower is an important decision, which if done improperly can render the light tower ineffective. After all, no light tower will be effective if placed in a location where operators cannot see or hear it at the most critical moments. As you noted, the control enclosure is not always the ideal location, as often they are not in the location where operators are typically stationed. So placing the light tower in an area that is in plain sight of operators is critical. Concurrently, the light tower should be mounted high enough so that it can be seen over greater distances. The caveat is that the light from the light tower may be directed away from the operator’s line of sight, thus reducing its effectiveness. Look for light towers with lensing that directs the light slightly downward, increasing the visibility when mounted at an elevated location. The LD6A series from IDEC is designed with this in mind. In addition, the LD6A features a unique color stripe design that provides optimal color contrast, which improves visibility and ensures that operators clearly understand the message being communicated by the light tower. For more information on LD6A light towers, please visit – Jim Dunn, Product Manager, IDEC


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