Blocks and Holders Fuse Blocks 111 Class H/K5 and R Fuse Blocks 112-116 Class J Fuse Blocks 117-119 Class T Fuse Blocks 120-123 Class G Fuse Blocks 124 Class CC/CD and Midget Fuse Blocks 125-126 Class CC and Midget Fuse Block Accessories 127 Fuse Block, Holders and Accessories 128-133 Semiconductor Fuse Blocks 134-136 POWR-BLOKS Distribution/Splicer Blocks 137-144 In-Line Watertight Fuseholders 145-150 www.littelfuse.com 2005 Littelfuse POWR-GARD Products CatalogBlocks and Holders Blocks and Holders Fuse Blocks General Information 4. Determine if NEC, CSA, UL, or other requirements are applicable If fuse blocks will be installed in equipment to be submitted for agency approval, the requirements should be obtained from the approving agency in advance of fuse and fuse block selection. 5. Select the type of wire termination A choice of three types of wire termination is available: a) Screw for use with spade lugs or ring terminals. * b) Screw with Pressure Plate for use with solid or stranded wire * without terminal. Recommended where vibration will be a factor. c) Box Lug the most durable. For use with all types of solid wire and Class B and Class C stranded wire. Not for use with welding cable or other rope-stranded conductors. 1 /4 Quick Connect terminals rated for up to 20A are * available on the Midget and Class CC fuse blocks. Fuse Block Selection The following guidelines should help simplify the selection of proper fuse blocks: Screw Screw Box with (S) Lug Pressure (C) 1. Determine the system voltage Plate Since fuses are selected on the basis of system voltage, fuse blocks are (P) selected to match the voltage rating of the fuse. 6. Decide on the number of poles in each block 2. Determine the design short-circuit current The number of poles for each set of fuses is determined by the Available and/or design short-circuit current is an important characteristics of the circuit. The option to gang individual fuse blocks consideration when determining the class of fuse and fuse blocks to into long strips will be determined by the available space and by the use. If available short-circuit current cannot be determined, or if it will type of wire being used. vary with equipment location, select fuses with a 200,000 ampere interrupting rating (A.I.R.) and mating fuse blocks with a withstand rating 7. Determine if fuse clips need to be reinforced of 200,000 amperes for maximum safety. Fuse clips may have a tendency to lose some of their tension over a period of time. This may be prevented by specifying reinforced fuse Class H fuse blocks will accept Class H or K5 fuses (which have an clips. Reinforced clips are standard on certain fuse blocks (see individual interrupting rating of up to 50,000 amperes) and Class R fuses (which product pages). have a 200,000 A.I.R.). To prevent the possibility of inserting a fuse with the incorrect interrupting rating, the use of Class R fuse blocks is Ordering Information recommended for use with Class R fuses. Use Class H fuse blocks with Class H or K5 fuses. These fuse blocks are dimensionally the same, but The Littelfuse fuse block part number consists of 6 or 7 components, as the Class R fuse blocks incorporate a rejection feature which allows only shown below and in the individual fuse block data tables. Class R fuses to be inserted. 3. Determine the type and ampere rating of the fuse to be used In addition to voltage and interrupting rating as discussed above, the fuse ampere rating, opening characteristics (fast acting or time-delay) and size are other important considerations in fuse selection. Once the fuse type is selected, the mating fuse block can be chosen. Fuse blocks are available in 30, 60, 100, 200, 400 and 600 amp ratings, and may be used with a fuse rated at the corresponding amperage rating or below. For example, a fuse block rated at 30 amperes may be used with a fuse rated from 0 to 30 amperes. For all Class R, H, J, T and 15, 20 For all Class CC, Midget and 30A & 60A Class G Fuse Blocks Class G Fuse Blocks 2005 Littelfuse POWR-GARD Products Catalog www.littelfuse.com 111