S&C Electric Company 122100-R4 SM-4 Refill Fuse Unit

The S&C Electric Company 122100-R4 SM-4 Refill Fuse Unit is a coordinating-speed refill element designed for SM-4 fuse holders in 14.4 kV distribution systems. It carries a 60E ampere rating and serves as a ready-to-install replacement fuse link, enabling rapid re-energization after a fault without replacing the entire assembly. This unit is specified for a nominal 14.4 kV with a maximum 17.0 kV in listed mountings and is suitable for use in SM-4 holders, with compatibility also noted for SME-4Z holders as listed in S&C’s refill-unit specifications. By integrating with the SM-4 protection scheme, the 122100R4 supports protective coordination and reliable interruption when needed, making it a practical solution for medium-voltage feeders and switchgear where quick restoration of service after a fault is desired. In S&C’s documentation, refill units in the SM-4 family are described as replaceable fuse elements for use in SM-4 and related holders, underscoring their role in maintaining continuity in 14.4 kV networks.