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© 2017 Littelfuse, Inc.
Specifications are subject to change without notice.
Revised: 03/03/17
FUSE
Circuit Protection Products and Mounting Accessories
Fuse ratings and other performance criteria are evaluated
under laboratory conditions and accptance criteria, as
defined in one or more of the various fuse standards. It is
important to understand these standards so that the fuse
can be properly applied to circuit protection applications.
UL/CSA/ANCE (Mexico) 248-14 FUSES FOR
SUPPLEMENTARY OVERCURRENT PROTECTION (600 Volts,
Maximum) (Previously UL 198G and CSA C22.2, No. 59)
UL LISTED
A UL Listed fuse meets all the requirements of the UL/
CSA/ANCE 248-14 Standard. Following are some of the
requirements. UL ampere rating tests are conducted at
100%, 135%, and 200% of rated current. The fuse must
carry 100% of its ampere rating and must stabilize at a
temperature that does not exceed a 75ºC rise.
The fuse must open at 135% of rated current within one
hour. It also must open at 200% of rated current within 2
minutes for 0-30 ampere ratings and 4 minutes for 35-60
ampere ratings.
The interrupting rating of a UL Listed fuse is 10,000
amperes AC minimum at 125 volts. Fuses rated at 250
volts may be listed as interrupting 10,000 amperes at 125
volts and, at least, the minimum values shown below at
250 volts.
Ampere Rating of
Fuse
Interrupting Rating
In Amperes
Voltage Rating
0 to 1 35 250 VAC
1.1 to 3.5 100 250 VAC
3.6 to 10 200 250 VAC
0.1 to 15 750 250 VAC
15.1 to 30 1500 250 VAC
Recognized Under the Component Program of
Underwriters Laboratories
The Recognized Components Program of UL is different
from UL Listing. UL will test a fuse to a specification
requested by the manufacturer. The test points can be
different from the UL Listed requirements if the fuse
has been designed for a specific application. Application
approval is required by UL for fuses recognized under the
Component Program.
UL 275 AUTOMOTIVE GLASS TUBE FUSES (32 Volts)
UL LISTED
UL ampere ratings tests are conducted at 110%, 135%,
and 200%. Interrupting rating tests are not required.
CSA Certification
CSA Certification in Canada is equivalent to UL Listing in
the United States.
The Component Acceptance Program of CSA is
equivalent to the Recognition Program at UL.
Standards
METI (Japan Ministry of Economy, Trade and Industry)
PS
E
METI APPROVAL
METI
approval in Japan is similar to UL Recognition in the
United States.
METI
B
has its own design standard and characteristics.
INTERNATIONAL ELECTROTECHNICAL
COMMISSION (IEC)
Publication 60127, Parts 1, 2, 3, 4, 6
The IEC organization is different from UL and CSA, since
IEC only writes specifications and does not certify. UL
and CSA write the specifications, and are responsible for
testing and certification.
Certification to IEC specifications are given by such
organizations as SEMKO (Swedish Institute of Testing
and Approvals of Electrical Equipment)
, BSI (British
Standards Institute)
and VDE (German Standard Insitute)
E
D
V
, as well as UL and CSA.
IEC Publication 60127 defines three breaking capacity
levels (interrupting rating). Low breaking capacity fuses
must pass a test of 35 amperes or ten times rated current,
whichever is greater, while enhanced breaking capacity
fuses must pass a test of 150 amperes and high breaking
capacity fuses must pass a test of 1500 amperes.
60127 Part 2
Sheet 1 — Type F Quick Acting, High Breaking Capacity
Sheet 2 — Type F Quick Acting, Low Breaking Capacity
Sheet 3 — Type T Time-Lag, Low Breaking Capacity
Sheet 4 — Style Fuses 1/4×1 1/4
Sheet 5 — Type T Time-Lag, High Breaking Capacity
Sheet 6 — Type T Time-Lag, Enhanced Breaking Capacity
The letters ‘F’ and ‘T’ represent the time-current
characteristic of the fast-acting and time delay fuses. One
of these letters will be marked on the end cap of the fuse.