Square D 9999SX8 Electrical Interlock Auxiliary Contact Block Assembly

The Square D 9999SX8 Auxiliary Contact Block delivers a ready-to-use signaling and interlock accessory for Type S NEMA motor starters and contactors. This external, field-mountable kit provides one normally open and one normally closed isolated contact (1 NO/1 NC) in a single block, enabling independent feedback or interlock logic without modifying the main device. Designed for use with Square D Size S contactors/starters across Sizes 00–7, the 9999SX8 expands control circuits by supplying an auxiliary contact pair that can drive piloting devices, relays, or PLC inputs. The contact block is rated for 10 A on the auxiliary contacts, offering solid performance for typical control-circuit loads, and it is explicitly described as field-convertible to accommodate different wiring configurations. As part of the Square D 9999 family, the 9999SX8 integrates with the existing starter assembly to provide additional contact points while preserving the original device envelope and mounting footprint. Typical applications include status indication, interlock arrangements in control panels, and remote signaling in industrial automation, where a compact, easily installed auxiliary contact block is preferred over wiring to separate devices.