Allen-Bradley 855T-B10FN6 USNT Terminal Block

Allen-Bradley 855T-B10FN6 USNT is a 70 mm blue control tower (stack light) module from the 855T signaling family, designed to mount in Allen-Bradley control panels and indicate machine status in automated systems. It operates on 120 V AC or DC and uses a flashing incandescent lamp to deliver high-visibility indication, making it suitable for industrial environments where quick status recognition is essential. This USNT variant is intended for use in stack-light configurations where multiple colored lamps convey different conditions on a single alerting tower, commonly applied on production lines, packaging equipment, and other process-control applications. Rockwell Automation lists this exact model as discontinued as of October 1, 2019, with the recommended functional replacement being the 856T-BB6, reflecting the product line’s evolution while preserving signaling functionality. When selecting a replacement, users typically consider compatibility with existing 855T base assemblies and the desired color/flash pattern to maintain consistent operator cues across the control panel. This model’s blue illumination stands out against typical panel backgrounds, aiding quick interpretation of status—such as run, standby, or fault conditions—within a multi-color signaling scheme.