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. 797-6061
Mfr. Part No.SF 139 R
BrandLimitor
MYR4.685
Each (In a Pack of 10)
units
+142°C +127°C 15 A 250V ac Axial - 4mm 8.5mm - - 1mm 18.5mm
RS Stock No. 176-9384
Mfr. Part No.SM 126 A0
BrandLimitor
MYR5.772
Each (In a Pack of 5)
units
+131°C +96°C 2 A 250V ac Axial - 2.5mm 9mm - - 0.6mm 38mm
RS Stock No. 176-9081
Mfr. Part No.P82 45 05100
BrandLimitor
MYR26.63
Each
units
+45°C - 2.5 A 250V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS Stock No. 204-7477
Mfr. Part No.Q82 A 130 05 100
BrandLimitor
MYR35.56
Each
units
+130°C - 2.5 A 250V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS Stock No. 176-9378
Mfr. Part No.SM 110 A0
BrandLimitor
MYR6.776
Each (In a Pack of 5)
units
+115°C +80°C 2 A 250V ac Axial - 2.5mm 9mm - - 0.6mm 38mm
RS Stock No. 797-6052
Mfr. Part No.SF 167 R
BrandLimitor
MYR5.324
Each (In a Pack of 10)
units
+167°C +153°C 15 A 250V ac Axial - 4mm 8.5mm - - 1mm 18.5mm
RS Stock No. 176-9182
Mfr. Part No.P82 110 05100
BrandLimitor
MYR31.40
Each
units
+110°C - 2.5 A 250V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS Stock No. 712-7301
Mfr. Part No.EYP1BF134
BrandPanasonic
MYR1.465
Each (In a Pack of 10)
units
+134°C +105°C 4 A 250V ac Axial - 2.2mm 6mm 6mm - 0.53mm 38mm
RS Stock No. 616-9969
Mfr. Part No.Q82 A 125 05 100
BrandLimitor
MYR28.93
Each
units
+125°C - 2.5 A 250V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS Stock No. 204-7483
Mfr. Part No.Q82 A 140 05 100
BrandLimitor
MYR29.54
Each
units
+140°C - 2.5 A 250V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS Stock No. 176-9148
Mfr. Part No.P82 80 05100
BrandLimitor
MYR28.63
Each
units
+80°C - 2.5 A 250V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS Stock No. 176-9198
Mfr. Part No.P82 125 05100
BrandLimitor
MYR23.43
Each
units
+125°C - 2.5 A 250V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS Stock No. 204-7427
Mfr. Part No.Q82 A 80 05 100
BrandLimitor
MYR28.45
Each
units
+80°C - 2.5 A 250V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS Stock No. 176-9104
Mfr. Part No.P82 55 05100
BrandLimitor
MYR23.43
Each
units
+55°C - 2.5 A 250V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm
RS Stock No. 797-6064
Mfr. Part No.SF 094 R
BrandLimitor
MYR6.034
Each (In a Pack of 10)
units
+99°C +84°C 15 A 250V ac Axial - 4mm 8.5mm - - 1mm 18.5mm
RS Stock No. 797-6058
Mfr. Part No.SF 150 R
BrandLimitor
MYR6.034
Each (In a Pack of 10)
units
+152°C +137°C 15 A 250V ac Axial - 4mm 8.5mm - - 1mm 18.5mm
RS Stock No. 176-9407
Mfr. Part No.SM 146 A0
BrandLimitor
MYR3.71
Each (In a Pack of 5)
units
+151°C +116°C 2 A 250V ac Axial - 2.5mm 9mm - - 0.6mm 38mm
RS Stock No. 116-114
Mfr. Part No.SM 092 A0 2A
BrandLimitor
MYR5.278
Each (In a Pack of 5)
units
+97°C +62°C 2 A 250V ac Axial - 2.5mm 9mm - - 0.6mm 38mm
RS Stock No. 797-6042
Mfr. Part No.SF 119 R
BrandLimitor
MYR4.654
Each (In a Pack of 10)
units
+121°C +106°C 15 A 250V ac Axial - 4mm 8.5mm - - 1mm 18.5mm
RS Stock No. 124-5058
Mfr. Part No.A2-3AF
BrandLimitor
MYR5.226
Each (In a Pack of 5)
units
+115°C +78°C 3 A 250V ac Radial A-3A-F - 6.3mm 6.2mm 2.5mm 0.6mm -