HSI Spot On Leverless Limit-Switches are designed to handle the most extreme operating environments. The four different Spot On models can sense farther, faster and last longer than the competition.
*SPOT ON WIRE COLOR DESIGNATIONS:
Black Wire = Common / Red Wire = Normally Closed / Blue Wire = Normally Open / Green Wire = Ground (steel housing only)
From 'Making Sense' Blog
Danger Danger: Designing for Hazardous Locations
A few weeks ago, I found out that I would be responsible for designing a new line of sensors that were to be certified for hazardous locations according to UL 1203. Fortunately, one of my coworkers had done this recently on a different product, so he knew how to point me in the right direction.