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UL FUSES
5x20mm
TIME DELAY
(Not Standardized)
QUICK ACTING
SHEET II SHEET IV
TIME DELAY
SHEET III
USA
IEC FUSES (IEC 127)
NORTH AMERICA
EUROPE (ASIA)
Low Breaking Capacity
35A - Transparent
COMPONENT RECOGNITION
PROGRAM
High Breaking Capacity
1500A - Non - Transparent
1/
4x1
1/
4"
CANADA
1/
4x1
1/
4"
5x20mm
Other
Dimensions
TIME DELAY
1/
4x1
1/
4"
5x20mm
UL 248-14
NON-TIME DELAY
QUICK ACTING
SHEET I
5x20mm
TIME DELAY
Other
Dimensions
1/
4x1
1/
4"
NON-TIME DELAY
Other
Dimensions
5x20mm
CSA FUSES
Any type of fuse
to manufacturer's
own specifications
Any type of fuse
to manufacturer's
own specifications
Other
Dimensions
1/
4x1
1/
4"
Possible Approvals
- CSA Certification
- UL Listing
Possible Approvals
- UL Listing
- CSA Certification
Possible Approvals
- UL Recognition
- CSA Component
Acceptance
- If Manufactured to
IEC Specifications:
SEMKO
VDE
BSI
Possible Approvals
- SEMKO
- VDE
- BSI
- UL Recognition
- CSA Component Acceptance
Possible Approvals
- UL Recognition
- CSA Component
Acceptance
- If Manufactured to
IEC Specifications:
SEMKO
VDE
BSI
How to Specify Fuses:
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.
1. Fuse Standards
There are three principal standards a fuse can be designed to:
1) UL 248-14
2) CSA 22.2 No. 59
3) IEC 127
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
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.
2. Approval Agencies
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
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.
A UL approved fuse will either bear the listing
or the
recognized
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.
CSA now has an equivalent to the Recognized Component
Program of UL: CSA Component Acceptance
. As far as fuse
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).
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.
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 I
n, whichever is greater,
3. Rated Current
The rated current of the fuse should be in accordance with the
operating current of the equipment to be protected. Consideration
CSA 22.2 NO. 59-M1984
COMPONENT ACCEPTANCE
PROGRAM
Fuse Standards and Approvals Around The World
1
About Non-Resettable Fuses
124