Black Box SP400A Opto Isolator

Black Box SP400A Opto-Isolator is a two-port Ethernet isolator offered as a standalone unit or wall-plate module that electrically separates two Ethernet networks while preserving data transmission. It supports 10/100/1000BASE-T and uses an internal fiber-optic link to carry signals between the RJ-45 interfaces on opposite sides, so the electrical path is blocked and ground loops or surges on one side cannot reach the other. It’s designed for environments where equipment resides on different grounds or power domains, and is commonly used to protect computers, switches, PLCs, and other networked devices in industrial or mixed IT/OT settings. The SP400A is available in the SP400A-R3 family and can be installed as a stand-alone device or as a wall-plate installation. Power is supplied by a Black Box power supply; retailers list PS015 as a compatible option, with other Black Box PS-series supplies used in practice. This part of Black Box’s opto-isolator lineup provides a measured approach to increasing network reliability by isolating electrical paths while maintaining full Ethernet throughput.