Littelfuse L300 User Manual

Fuse Blocks

Screw

with

Pressure

Plate

(P)

Screw

(S)

Box
Lug

(C)

General Information

Blocks and Holders

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
b) Screw with Pressure Plate

c) Box Lug — the most durable. For use with all types of solid wire and

1/4” Quick Connect terminals rated for up to 20A are

*

— for use with spade lugs or ring terminals.

*

without terminal. Recommended where vibration will be a factor.

Class B and Class C stranded wire. Not for use with welding cable or
other rope-stranded conductors.

available on the Midget and Class CC fuse blocks.

— for use with solid or stranded wire

*

Fuse Block Selection

The following guidelines should help simplify the selection of proper
fuse blocks:

1. Determine the system voltage

Since fuses are selected on the basis of system voltage, fuse blocks are
selected to 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 blocks to
use. If available short-circuit current cannot be determined, or if it will
vary with equipment location, select fuses with a 200,000 ampere
interrupting rating (A.I.R.) and mating fuse blocks with a withstand rating
of 200,000 amperes for maximum safety.

Class H fuse blocks will accept Class H or K5 fuses (which have an
interrupting rating of up to 50,000 amperes) and Class R fuses (which
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
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 Class R fuse blocks incorporate a rejection feature which allows only
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.

6. Decide on the number of poles in each block

The number of poles for each set of fuses is determined by the
characteristics of the circuit. The option to gang individual fuse blocks
into long strips will be determined by the available space and by the
type of wire being used.

7. Determine if fuse clips need to be reinforced

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
clips. Reinforced clips are standard on certain fuse blocks (see individual
product pages).

Ordering Information

The Littelfuse fuse block part number consists of 6 or 7 components, as
shown below and in the individual fuse block data tables.

Blocks and Holders

© 2005 Littelfuse • POWR-GARD™ Products Catalog

For all Class R, H, J, T and 15, 20
& 60A Class G Fuse Blocks

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For all Class CC, Midget and 30A
Class G Fuse Blocks

111

Class J Fuse Blocks

1.16"

[29.4]

.30"
TYP.

[7.6]



1.69"

[42.8]

3.38"

[85.7]

.57"

[14.5]

.71"

[17.9]

1.95"

[49.5]

.216[5.5] x .79[20.0] SLOT
MOUNTING HOLE

1.69"

[42.8]

3.38"

[85.7]

.57

[14.5]

" TYP.

2.20"

[56.0]

1.04"

[26.4]

1.69"

[42.8]

3.38"

[85.7]

3.25"

[82.5]

1.04"

[26.4]

1 POLE 2 POLE 3 POLE



600 Volt

Blocks and Holders

Class J 600V

Connector Type

Amp

Rating

No. of
Poles

Catalog
Number

1 LJ60030-1 S (R) P (R) C (R)

30

2 LJ60030-2 S (R) P (R) C (R)
3 LJ60030-3 S (R) P (R) C (R)

Adder LJ60030-A S (R) P (R) C (R)

1 LJ60060-1 C (R)

60

2 LJ60060-2 C (R)
3 LJ60060-3 C (R)

100

200

400

600

1 LJ60100-1 CR
3 LJ60100-3 CR
1 LJ60200-1 C
3 LJ60200-3 C
1 LJ60400-1 CR
3 LJ60400-3 CR
1 LJ60600-1 CR
3 LJ60600-3 CR

Note: Reinforcing springs standard on all Class J fuse blocks rated 100A and above.

*For optional fuse block covers, refer to POWR-Covers section of this catalog. For
reinforcing clips on blocks rated 30-60 amp, add “R” suffix to connector type.

(Add Suffix Shown)

Pressure

Screw

Plate

Box
Lug

Maximum
Wire Size

S & P = #10 CU

C = #6 CU

C = #2 CU-AL

#2/0 CU-AL

250 MCM CU-AL

(2) 350 MCM CU-AL

(2) 500 MCM CU-AL

Features/Benefits

• Phenolic blocks have side barriers for isolation.

• Spring reinforced fuse clips are standard on 100A and larger blocks.
Reinforcing springs are optional on 30 and 60 amp blocks.

•

Space saving 30A design — Up to 45% smaller than existing

30A fuse blocks. 30A interlocking adder block available to create
any number of poles (consult factory for availability). Integral DIN rail
mount allows this block to be securely fastened to 35 mm “hat” type
DIN rails without the use of tools.

LJ60 030

Specifications

Voltage Ratings: 600 Volts
Ampere Ratings: 0 – 600 amperes
Approvals: UL Listed: File No. E14721

CSA Certified: File No. LR73091

Recommended Fuses

JTD_ID/JTD (time-delay) and JLS (fast acting) series fuses

Blocks and Holders

© 2005 Littelfuse • POWR-GARD™ Products Catalog

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