About Non-Resettable Fuses
How to Specify Fuses:
Kingdom). It is important to understand that UL and CSA not only
write standards but also issue conformance approvals. IEC,
however, limits itself to writing the standards. Conformance with
these IEC standards is tested by VDE, SEMKO, and BSI.
The safety of electronic and electric equipment not only depends
upon the use of shock-safe primary circuit components
(fuseholders, voltage selector switches, power entry modules,
etc.) designed primarily for the protection of service personnel, but
also on devices protecting the safe operation of the equipment
itself. Since in many cases fuses are the only means of providing
circuit protection in the event of overloads or fault conditions, we
suggest the following considerations be observed when fuses are
being selected.
®
A UL approved fuse will either bear the listing
recognized
or the
mark. A listed fuse meets all the requirements of
fuse Standard UL 248-14. A fuse with the recognition mark is
tested under the Component Program of UL to the fuse
manufacturer’s own specifications.
1. Fuse Standards
CSA now has an equivalent to the Recognized Component
There are three principal standards a fuse can be designed to:
Program of UL: CSA Component Acceptance
. As far as fuse
1) UL 248-14 2) CSA 22.2 No. 59 3) IEC 127
size is concerned, UL and CSA accept a wide range of
dimensions (including the 5 x 20mm size, notably with UL/CSA
blowing characteristics!) IEC has standardized around the 5 x
20mm size (notably with IEC blowing characteristics!). The only
other size in IEC’s document is the 1/4 x 11/4" fuse (only in quick
acting, low breaking capacity configuration).
Please note that these standards may not necessarily be
compatible with each other. The main difference between the
various standards are as follows:
- different blowing characteristics between UL/CSA and
IEC standards
- different temperature rise requirements between UL and
CSA standards
Because of overlapping dimensions between the various
standards, caution has to be used when trying to categorize or
identify a 5 x 20mm or 1/4 x 11/4" fuses. The chart below
summarizes the aforementioned.
The incompatibility of these standards makes it impossible to use
one and the same fuse across the world in a given application.
Attention needs to be given to the fact that the governing
Standard in Europe is IEC. Observation of this fact in the early
design stage will save trouble and confusion during the agency
approval process. Note: new fuse qualifications have been
established for low-voltage fuses; reference EIA/IS-722.
IMPORTANT: All CENELEC (European Committee for Electronic
Standards) countries, including EC and EFTA nations, require a
high-breaking capacity fuse-link, if the short circuit current through
the fuse-link is more than 35A or 10 x In, whichever is greater,
effective January 1st, 1993. Please refer to Series SP (pg. 145)
and SPT (pg. 148).
2. Approval Agencies
3. Rated Current
The rated current of the fuse should be in accordance with the
operating current of the equipment to be protected. Consideration
National approval agencies which approve miniature type fuses
conforming to either UL, CSA, or IEC standards are: UL (USA),
CSA (Canada), VDE (Germany), SEMKO (Sweden), BSI (United
Fuse Standards and Approvals Around The World
NORTH AMERICA
EUROPE (ASIA)
USA
CANADA
CSA FUSES
UL FUSES
IEC FUSES (IEC 127)
CSA 22.2 NO. 59-M1984
COMPONENT ACCEPTANCE
High Breaking Capacity
1500A - Non - Transparent
Low Breaking Capacity
35A - Transparent
COMPONENT RECOGNITION
PROGRAM
UL 248-14
PROGRAM
NON-TIME DELAY
5x20mm
TIME DELAY
TIME DELAY
5x20mm
NON-TIME DELAY
5x20mm
QUICK ACTING TIME DELAY
QUICK ACTING
SHEET II SHEET IV
TIME DELAY
SHEET III
SHEET I
(Not Standardized)
5x20mm
Other 1/4x1 1/4" Other
Any type of fuse
to manufacturer's
own specifications
1/4x1 1/4"
1/4x1 1/4"
Other
1/ x1 1/4"
Other
Any type of fuse
to manufacturer's
own specifications
Dimensions4
5x20mm
1/4x1 1/4"
5x20mm
Dimensions
Dimensions
5x20mm
5x20mm
Dimensions
Possible Approvals
- SEMKO
Possible Approvals
- UL Recognition
Possible Approvals
- UL Recognition
Possible Approvals
- UL Listing
Possible Approvals
- CSA Certification
- UL Listing
- CSA Component
Acceptance
- VDE
- CSA Component
Acceptance
- CSA Certification
- BSI
- If Manufactured to
IEC Specifications:
- If Manufactured to
IEC Specifications:
- UL Recognition
- CSA Component Acceptance
SEMKO
VDE
SEMKO
VDE
BSI
BSI
124
SCHURTER [ SCHURTER INC. ]
