Blocks 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 111Blocks and Holders
Class T Fuse Blocks
300 and 600 Volt
Features/Benefits
Bases are molded phenolic. To provide a low resistance connection and
long-range reliability, steel reinforcing springs are supplied as standard.
Larger blocks employ an integral heat sink for maximum heat dissipation.
Specifications
Voltage Ratings: 300 Volts AC
600 Volts AC
Ampere Ratings: 0 600 amperes
Approvals: UL Listed (File No. E14721)
CSA Certified (File No. LR73091)
Recommended Fuses
JLLN (300V) and JLLS (600V) series fuses
300 and 600 volt fuse blocks are designed for use with miniaturized Class T
fuses. Class T fuses are very fast acting, current-limiting, and approximately
one-third the size of electrically comparable Class RK1 fuses.
Class T 300V Class T 600V
Connector Type Connector Type
Amp No. of Catalog Maximum Amp No. of Catalog Maximum
(Add Suffix Shown) (Add Suffix Shown)
Rating Poles Number Wire Size Rating Poles Number Wire Size
Screw Box Lug Screw Box Lug
2 LT30030-2 CR S = #10 CU 1 LT60030-1 SR CR S = #10 CU
30
3 LT30030-3 CR C = #2 CU 30 2 LT60030-2 SR CR C = #2 CU-AL
2 LT30060-2 CR 3 LT60030-3 SR CR
60 3 LT30060-3 CR C = #2 CU-AL 1 LT60060-1 CR
4 LT30060-4 CR 60 2 LT60060-2 CR C = #2 CU-AL
3 LT60060-3 CR
1 LT30100-1 C
100 2 LT30100-2 C #20 CU-AL 1 LT60100-1 C
100 2 LT60100-2 C #20 CU-AL
3 LT30100-3 C
200 1 LT30200-1 C 250 MCM CU-AL 3 LT60100-3 C
400 1 LT30400-1 C (2) 250 MCM CU-AL 200 1 LT60200-1 C 250 MCM CU-AL
600 1 LT30600-1 C (2) 500 MCM CU-AL 400 1 LT60400-1 C (2) 250 MCM CU-AL
600 1 LT60600-1 C (2) 500 MCM CU-AL
Note: Reinforcing springs standard on all 300 volt Class T fuse blocks up to 100
amperes. 300 volt Class T blocks 200 amperes and larger have stud mountings.
Note: Reinforcing springs standard on all 600 volt Class T fuse blocks up to 60
amperes. 600 volt Class T blocks 100 amperes and larger have stud mountings.
0.218" [5.54] THRU
LT30030
1.19" 1.13" 0.39" [9.91] C'BORE
1.19
x 0.44" [9.91] DP.
[30.2] [28.6]
[30.2]
2.88"
2.88
[73.0] [73.0]
2.25"
2.25
[57.2]
[57.2]
1.13"
1.13 0.62"
.31 [15.9]
.31"
[28.6] [28.6]
[7.9]
[7.9]
1.12"
3.50"
2.38
[88.9] [28.5]
[60.3]
2 POLE 3 POLE
120 www.littelfuse.com 2005 Littelfuse POWR-GARD Products Catalog
Blocks and Holders