UL Class Fuses

Norberg-IES carries an extensive inventory of UL Class fuses designed for applications such as motor protection and power distribution. Our fuse specialists are trained to you help identify fuses and to provide assistance in locating a replacement or determining an accurate cross reference for hard to find fuses or fuse hardware.

Fuse Data Sheets

UL Class Fuse Types

Class L Read more...
Class J Read more...
Class RK1 Read more...
Class RK5 Read more...
Class T Read more...
Class CC Read more...
Midget
One Time
Renewable
Fuse Blocks
Power Distribution Blocks
Finger Safe Fuse Holders

To check availability on any UL class fuse or to place an order:

Class L Fuses

These non-renewable fuses are current-limiting and conform to 248-10. They’re designed for the protection of feeders and service entrance equipment.

Current ratings for UL Class L fuses range from 601A to 6000A, and the voltage rating is 600VAC. Class L fuses are available with DC ratings. Available case sizes are 800A, 1,200A, 1,600A, 2,000A, 2,500A, 3,000A, 4,000A, 5,000A, and 6,000A. The interrupting rating is 200kA rms symmetrical. (300kA fuses are available.)

As with the other classes of fuses conforming to 248 (G, J, R, and T), Class L fuses must be labeled “Current Limiting.” They may be labeled “Time Delay,” although the standard doesn’t have a requirement for their time-delay characteristics. (Back to top)

Class J Fuses

These non-renewable fuses are current-limiting and conform to 248-8. Current ratings of UL Class J fuses range from 0A to 600A, and the voltage rating is 600VAC. Class J fuses are available with DC ratings. The interrupting rating is 200kA rms symmetrical. Fuses with 300kA interrupting ratings are available. Time-delay labeling is available if the fuse meets the UL optional time-delay test requirements of a minimum 10-sec opening time at 500% of fuse current rating. (Back to top)

Class RK1 & RK5 Fuses

These non-renewable fuses are made in 250VAC and 600VAC ratings, with current ratings from 0A to 600A. Class R fuses are available with DC ratings. They have an interrupting rating of 200kA rms symmetrical and are separated into two separate classes, RK1 and RK5. RK1 fuses are available with interrupting ratings of 300kA.

Both RK1 and RK5 fuses are current-limiting and meet standard-prescribed maximum peak instantaneous let-through current and maximum I2t let-through energy requirements.

Actually, Class RK1 and RK5 fuses are Class K-1 and K-5 fuses with ferrules and knife blades modified to conform to Class R rejection requirements. The grooved ring in the ferrule and the slot in the knife blade, when used in conjunction with special fuse holders designed to accept Class R fuses only, prevent interchanging of any other fuse class with the installed Class R fuse.

All Class R fuses must be labeled “Current Limiting.” They may be labeled “Time Delay,” indicating that they meet the optional time-delay test by not opening in less than 10 seconds at 500% of fuse ampere rating. (Back to top)

Class T Fuses

These non-renewable fuses are current-limiting and are designed for protection of feeders and branch circuits in accordance with the NEC. Current ratings range from 0A to 1200A for 300V rated fuses, and 0A to 1,200A for 600VAC rated fuses. Class T fuses are available with DC ratings. The interrupting rating is 200kA rms symmetrical.

As mentioned for the Class L fuses, Class T fuses also must be labeled “Current Limiting,” and may be labeled “Time Delay” if they pass time-delay requirements. (Back to top)

Class CC Fuses

These non-renewable fuses are current-limiting and intended for the protection of components sensitive to short-time overloads, non-inductive loads, and short-circuit protection of motor circuits.

Current ratings range from 0A to 30A, and the voltage rating is 600VAC. Class CC fuses are available with DC ratings. The interrupting rating is 200kA rms symmetrical.

Class CC fuses must be labeled “Current Limiting,” and may be labeled “Time Delay.” The optional time-delay test requirements for this class of fuses (a minimum 12-sec opening time at 200% fuse current rating) is different than that of other larger body fuses.

Because Class CC fuses are the most current limiting, rating for rating, as compared to other types of control power fuses, they’re particularly suited for use in IEC devices. (Back to top)

To check availability on any UL class fuse or to place an order: