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. 176-9132
Mfr. Part No.P82 70 05100
BrandLimitor
R 91.47
Each
units
+70°C - 2.5 A 250 V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS stock no. 176-9378
Mfr. Part No.SM 110 A0
BrandLimitor
R 16.49
Each (In a Pack of 5)
units
+115°C +80°C 2 A 250 V ac Axial - 2.5mm 9mm - - 0.6mm 38mm
RS stock no. 176-9384
Mfr. Part No.SM 126 A0
BrandLimitor
R 16.468
Each (In a Pack of 5)
units
+131°C +96°C 2 A 250 V ac Axial - 2.5mm 9mm - - 0.6mm 38mm
RS stock no. 111-7300
Mfr. Part No.STC-183
BrandSelco
R 27.869
Each (In a Pack of 10)
units
+84°C +60°C 10 A 250 V ac Axial STC Series 4mm 10.5mm - - 1.024mm 35mm
RS stock no. 176-9148
Mfr. Part No.P82 80 05100
BrandLimitor
R 91.47
Each
units
+80°C - 2.5 A 250 V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS stock no. 616-9969
Mfr. Part No.Q82 A 125 05 100
BrandLimitor
R 118.20
Each
units
+125°C - 2.5 A 250 V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS stock no. 176-9097
Mfr. Part No.P82 50 05100
BrandLimitor
R 91.29
Each
units
+50°C - 2.5 A 250 V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS stock no. 176-9198
Mfr. Part No.P82 125 05100
BrandLimitor
R 79.80
Each
units
+125°C - 2.5 A 250 V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS stock no. 797-6030
Mfr. Part No.SF 229 R
BrandLimitor
R 16.563
Each (In a Pack of 10)
units
+229°C +200°C 15 A 250 V ac Axial - 4mm 8.5mm - - 1mm 18.5mm
RS stock no. 176-9104
Mfr. Part No.P82 55 05100
BrandLimitor
R 91.47
Each
units
+55°C - 2.5 A 250 V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS stock no. 712-7326
Mfr. Part No.EYP05BE115
BrandPanasonic
R 6.383
Each (In a Pack of 10)
units
+115°C +95°C 3 A 250 V ac Axial - 1.8mm 5mm - - 0.53mm 38mm
RS stock no. 176-9154
Mfr. Part No.P82 90 05100
BrandLimitor
R 97.91
Each
units
+90°C - 2.5 A 250 V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS stock no. 797-6064
Mfr. Part No.SF 094 R
BrandLimitor
R 16.674
Each (In a Pack of 10)
units
+99°C +84°C 15 A 250 V ac Axial - 4mm 8.5mm - - 1mm 18.5mm
RS stock no. 124-5057
Mfr. Part No.A1-5AF
BrandLimitor
R 17.676
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. 797-6061
Mfr. Part No.SF 139 R
BrandLimitor
R 14.355
Each (In a Pack of 10)
units
+142°C +127°C 15 A 250 V ac Axial - 4mm 8.5mm - - 1mm 18.5mm
RS stock no. 124-5062
Mfr. Part No.A8-5AF
BrandLimitor
R 18.92
Each (In a Pack of 5)
units
+150°C +105°C 5 A 250 V ac Radial A-5A-F - 8mm 6.6mm 2.6mm 0.6mm -
RS stock no. 176-9081
Mfr. Part No.P82 45 05100
BrandLimitor
R 91.83
Each
units
+45°C - 2.5 A 250 V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS stock no. 176-9126
Mfr. Part No.P82 60 05100
BrandLimitor
R 91.47
Each
units
+60°C - 2.5 A 250 V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS stock no. 124-5058
Mfr. Part No.A2-3AF
BrandLimitor
R 14.77
Each (In a Pack of 5)
units
+115°C +78°C 3 A 250 V ac Radial A-3A-F - 6.3mm 6.2mm 2.5mm 0.6mm -
RS stock no. 204-7427
Mfr. Part No.Q82 A 80 05 100
BrandLimitor
R 88.90
Each
units
+80°C - 2.5 A 250 V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm