Square D 9999R-7 Two Pole Disconnect Safety Switch Interlock

Square D 9999R-7 is a field-installable Class 9999 interlock kit for use with two-pole Square D disconnect safety switches. It provides a mechanical interlock that disconnects a separately supplied control circuit whenever the main disconnect is placed in the OFF position, ensuring that control power is de-energized during maintenance and reducing the risk of unintended energization. As part of Square D’s Class 9999 interlock family, the 9999R-7 is designed for retrofit installation on compatible general‑duty disconnect switches to enable interlocked, safe operation within electrical enclosures. Typical applications include industrial control panels and safety enclosures where a secondary circuit must not energize when the main switch is operated, supporting proper sequencing, personnel safety, and compliance with interlock practices for two-pole configurations.