CLT Fuses

Eaton's Cutler-Hammer CLT fuses are designed specifically to provide fault protection on high capacity indoor and underground distribution systems. These general purpose current limiting fuses meet or exceed C37 standards for this class of distribution fuse.

CLT fuses are constructed with pure silver fuse elements, high purity silica sand fill with controlled grain size, a specifically designed core, and a glass-epoxy outer casing.

During a high fault current, the silver element(s) melts almost instantly losing energy to the surrounding sand. The energy melts the sand forming a glass-like substance commonly referred to as "fulgurite".  The arc voltage rapidly increases to about three times the fuse voltage rating, forcing the current to zero. The fault current is interrupted in one-half cycle or less without noise or expulsion of gases.

Current limiting action occurs only when the current is above the threshold current for the fuse, i.e., the current is high enough to melt the fuse element(s) before the peak value of current is reached in the first half cycle.

Low level currents are cleared by the melting of a tin solder drop on the fuse element, which in turn causes the silver element to melt. This is called the M-effect. The silver element then burns back until there is sufficient internal gap to interrupt the current.


  • Quiet, safe operation
  • Limits fault current let-through
  • Arc-voltage protection
  • Maintains non-conductance after interruption
  • Low-cost transformer protection


  • Used in conjunction with EFD load break switches, which meet the full switching requirements of underground distribution systems utilizing pad-mounted transformers.
  • Pad-mounted transformer drawout wells
  • In conjunction with LBOR oil switches as a means of low-cost transformer protection


  • Eaton Cutler Hammer Westinghouse

Data Sheets: