Littelfuse LT601002C

The following guidelines help simplify the selection of an appropriate fuse holder:

1. Determine the system voltage: Since fuses are selected based on system voltage, the fuse holder selection should match the voltage rating of the fuse.
2. Determine the design short-circuit current: Available and/or design short-circuit current is an important consideration when determining the class of fuse and fuse holder to use. If the available short-circuit current cannot be determined, or if it varies with equipment location, fuses with a 200,000 ampere interrupting rating (A.I.R.) and matching fuse holders with a 200,000 ampere withstand rating should be selected for maximum safety. Class H fuse holders accept Class H or Class K5 fuses (interrupting ratings up to 50,000 amperes) and Class R fuses (interrupting rating of 200,000 A.I.R.). To prevent insertion of fuses with incorrect interrupting ratings, it is recommended to use Class R fuse holders with Class R fuses, and Class H fuse holders with Class H or Class K5 fuses. These fuse holders are identical in size, but Class R fuse holders feature a rejection function that only accepts Class R fuses.
3. Determine the fuse type and ampere rating to use: In addition to the voltage and interrupting ratings above, the fuse's ampere rating, blowing characteristics (fast-acting or time-delay), and dimensions are other important considerations in fuse selection. Once the fuse type has been selected, a matching fuse holder can be chosen. Fuse holders are available in 30, 60, 100, 200, 400, and 600 ampere ratings for use with fuses of the corresponding or lower ampere rating. For example, a fuse holder rated at 30 amperes can be used with fuses rated from 0 to 30 amperes.
4. Determine whether NEC, CSA, UL, or other requirements apply: If the fuse holder is to be installed in equipment requiring agency approval, the relevant requirements should be obtained from the approving agency before selecting fuses and fuse holders.
5. Select the wire termination type: Three wire termination types are available: a) Screw — for use with spade terminals or ring terminals. b) Screw with pressure plate — for use with solid or stranded wire without terminals. Recommended where vibration is a factor. c) Box connector — most durable. Suitable for all types of solid wire and Class B and Class C stranded wire. Not suitable for welding cable or other rope-stranded conductors. 1/4-inch quick-connect terminals rated up to 20A are available on miniature and Class CC fuse holders.
6. Determine the number of poles per fuse holder: The number of poles per fuse group is determined by circuit characteristics. The choice of combining individual fuse holders into a strip will depend on available space and the type of wire used.
7. Determine whether reinforced fuse clips are required: Fuse clips may lose some tension over time. This can be prevented by specifying reinforced fuse clips. Reinforced clips are standard on certain fuse holders (see individual product pages).

• Base made of molded phenolic material. Steel reinforced springs standard for low-resistance connections and long-term reliability.
• Larger fuse holders feature integrated heat sinks for maximum heat dissipation.