Class L Time-Delay & Fast-Acting Fuses

Bullet ™ Class L Time-Delay Fuses

Edison Class L fuses, Catalog Numbers LCL time-delay or LCU fast acting are recommended for high capacity main, feeder or branch circuits in power distribution systems and for special applications such as system upgrading, install ahead of network protectors, etc. The choice of LCL or LCU depends on the extent of mixed inductive and non-inductive loads diversity. Apply LCL fuses for protection of large individual motor circuits. Size LCL fuses at 150% or more of the motor nameplate current rating by checking starting characteristics against minimum melt Time-Current Curve.



Data Sheet #1307 (LCL)

Data Sheet #1308 (LCU)

Catalog Number LCL (Time-Delay), LCU (Fast-Acting)
Volts 600Vac
Amps - LCL - 300 - 4000A
- LCU - 601 - 6000A
Interrupting Rating 200kA RMS Sym
Agency Approvals UL Listed, Class L, Guide JDDZ, File E162363; CSA Certified HRC-L per C22.2, No. 248.10
Benefits • “O-ring” construction insures maximum current limiting ability
• Silver-plated micro-peened terminals
• High strength melamine fuse tubes
Applications • LCL - Recommended for AC power distribution system mains and large feeders
• LCU - Recommended for non-inductive heating and lighting loads. Also suitable for protection of low interrupting rating circuit breakers.
Recommended Sizing LCL - 150% or more of motor full load current.


Install Class L Fuses in switches rated 601-6000 amps and in AMP RATINGS and “time-delay” or “fastacting” types as shown on the plans. Installed and spare “time-delay” fuses shall be Catalog Number LCL and “fastacting” fuses shall have silver links and be Catalog Number LCU. Fuses shall be Edison fuses or equivalent submitted to the design engineer for approval 10 days prior to the project bid date.

Mounting of “Bolt-On” Fuses shall be made by installing stainless steel bolts of correct number, diameter and length*, stainless steel spring washers on each side of the bolt and stainless steel nuts. The nuts shall be tightened to the torque recommended by ASTM Standards for the bolt size used.

LCL: Time-delay of 5 seconds minimum at 500% rated current allows closer sizing.

NOTE: LCL 300 - 500 amp fuses are physically the same as 800 amp size; Use in 800 amp switch where load current is not fully utilized and a smaller fuse amp size is desired. Also useful in new installations to allow for future upgrades in service.

Recommended Upgrade: None Available