Thermal Fuses

What are thermal fuses?

Thermal fuses, also called thermal cutoffs, are a safety device used in electrical circuits to provide protection against appliances overheating. Thermal fuses are normally supplied in an axial or radial package, although some thermal fuses are now available as a chip.

How do thermal fuses work?

Thermal fuses work in a similar way to electrical cartridge fuses; when the conditions exceed a certain limit, the circuit will be broken. For thermal fuses, the limit is based on temperature. Thermal fuses typically contain a small pellet within them or have a thin piece of wire which melts at a certain temperature. When the pellet or piece of wire melts, the circuit breaks. This is called 'blowing out' or 'burning out'.

Single-use thermal fuses and resettable thermal fuses

Most thermal fuses are single-use and non-resettable. Once the pellet or piece or wire has melted, the thermal fuse will need replacing before you can operate your appliance again. Resettable fuses are available but tend to have a higher upfront cost than single-use counterparts. For resettable fuses, when the wax pellet within melts, the circuit is broken. However, as the appliance cools, the wax pellet will cool and solidify. This will complete the circuit again and your appliance can be used.

What are thermal fuses used for?

Thermal fuses are used to protect appliances from overheating and can be found in domestic and industrial applications. They are a safety device that helps to prevent fires. For example, thermal fuses can be found in hairdryers, tumble dryers and coffee machines.

What is the difference between functioning temperature and holding temperature?

All thermal fuses have a holding temperature rating and functioning temperature rating. These are key measurements to consider when choosing the right thermal fuse for your application. The holding temperature, normally measured in Celsius, defines what temperature the fuse can operate at continuously without blowing. This is the limit of the safe temperature range for the fuse. The functioning temperature is the lowest temperature rating (also in Celsius) at which the thermal fuse will blow and the circuit will break.

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Description Price Functioning Temperature Holding Temperature Maximum Current Voltage Rating Lead Orientation Series Body Diameter Body Height Body Length Body Width Wire Diameter Wire Length
RS Stock No. 195-8752
Mfr. Part No.NIS6350MT1TXG
SGD0.82
Each (On a Reel of 3000)
units
- - 3 A 5 V - NIS6350 - 0.75mm 3.1mm 3.1mm - -
RS Stock No. 124-5057
Mfr. Part No.A1-5AF
BrandLimitor
SGD1.732
Each (In a Pack of 5)
units
+102°C +63°C 5 A 250 V ac Radial A-5A-F - 8mm 6.6mm 2.6mm 0.6mm -
RS Stock No. 797-6058
Mfr. Part No.SF 150 R
BrandLimitor
SGD1.496
Each (In a Pack of 10)
units
+152°C +137°C 15 A 250 V ac Axial - 4mm 8.5mm - - 1mm 18.5mm
RS Stock No. 195-8753
Mfr. Part No.NIS6350MT1TXG
SGD1.142
Each (In a Pack of 250)
units
- - 3 A 5 V - NIS6350 - 0.75mm 3.1mm 3.1mm - -
RS Stock No. 124-5056
Mfr. Part No.A1-3AF
BrandLimitor
SGD1.58
Each (In a Pack of 5)
units
+102°C +40°C 3 A 250 V ac Radial A-3A-F - 6.3mm 6.2mm 2.5mm 0.6mm -
RS Stock No. 712-7351
Mfr. Part No.EYP2MP098AU
BrandPanasonic
SGD0.745
Each (In a Pack of 10)
units
+98°C +65°C 2 A 32 V dc Axial - - 0.64mm 4.2mm 2.7mm 2.3mm 7.9mm
RS Stock No. 176-9182
Mfr. Part No.P82 110 05100
BrandLimitor
SGD8.66
Each
units
+110°C - 2.5 A 250 V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS Stock No. 111-7813
Mfr. Part No.SWTC-464-3535
BrandSelco
SGD2.466
Each (In a Pack of 10)
units
+240°C +193°C 10 A 250 V ac Axial SWTC Series 4mm 10mm - - 1mm 35mm
RS Stock No. 111-7095
Mfr. Part No.SWTC-183-3535
BrandSelco
SGD2.396
Each (In a Pack of 10)
units
+84°C +57°C 10 A 250 V ac Axial SWTC Series 4mm 10mm - - 1mm 35mm
RS Stock No. 797-6049
Mfr. Part No.SF 090 R
BrandLimitor
SGD1.496
Each (In a Pack of 10)
units
+94°C +79°C 15 A 250 V ac Axial - 4mm 8.5mm - - 1mm 18.5mm
RS Stock No. 124-5060
Mfr. Part No.A4-3AF
BrandLimitor
SGD1.40
Each (In a Pack of 5)
units
+130°C +90°C 3 A 250 V ac Radial A-3A-F - 6.3mm 6.2mm 2.5mm 0.6mm -
RS Stock No. 195-8755
Mfr. Part No.NIS6350MT2TXG
SGD1.142
Each (In a Pack of 250)
units
- - 3 A 5 V - NIS6350 - 0.75mm 3.1mm 3.1mm - -
RS Stock No. 712-7301
Mfr. Part No.EYP1BF134
BrandPanasonic
SGD0.515
Each (In a Pack of 10)
units
+134°C +105°C 4 A 250 V ac Axial - 2.2mm 6mm 6mm - 0.53mm 38mm
RS Stock No. 797-6046
Mfr. Part No.SF 070 R
BrandLimitor
SGD1.496
Each (In a Pack of 10)
units
+73°C +58°C 15 A 250 V ac Axial - 4mm 8.5mm - - 1mm 18.5mm
RS Stock No. 2508955936
Mfr. Part No.NTE8139
SGD2.67
Each
units
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