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 Priced to Clear
RS Stock No. 712-7284
Mfr. Part No.EYP2BN109
BrandPanasonic
£0.319
Each (In a Pack of 10)
Units
+114°C +90°C 5 A 250V ac Axial - 3mm 9mm 9mm - 0.6mm 38mm -
RS Stock No. 176-9148
Mfr. Part No.P82 80 05100
BrandLimitor
£3.95
Each
Units
+80°C - 2.5 A 250V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm -
RS Stock No. 797-6030
Mfr. Part No.SF 229 R
BrandLimitor
£0.713
Each (In a Pack of 10)
Units
+229°C +200°C 15 A 250V ac Axial - 4mm 8.5mm - - 1mm 18.5mm -
RS Stock No. 111-7300
Mfr. Part No.STC-183
BrandSelco
£1.159
Each (In a Pack of 10)
Units
+84°C +60°C 10 A 250V ac Axial STC Series 4mm 10.5mm - - 1.024mm 35mm -
RS Stock No. 712-7301
Mfr. Part No.EYP1BF134
BrandPanasonic
£0.257
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. 797-6049
Mfr. Part No.SF 090 R
BrandLimitor
£0.718
Each (In a Pack of 10)
Units
+94°C +79°C 15 A 250V ac Axial - 4mm 8.5mm - - 1mm 18.5mm -
RS Stock No. 797-6055
Mfr. Part No.SF 129 R
BrandLimitor
£0.718
Each (In a Pack of 10)
Units
+133°C +118°C 15 A 250V ac Axial - 4mm 8.5mm - - 1mm 18.5mm -
RS Stock No. 204-7477
Mfr. Part No.Q82 A 130 05 100
BrandLimitor
£4.01
Each
Units
+130°C - 2.5 A 250V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm -
RS Stock No. 797-6042
Mfr. Part No.SF 119 R
BrandLimitor
£0.334
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. 712-7307
Mfr. Part No.EYP1BF115
BrandPanasonic
£0.247
Each (In a Pack of 10)
Units
+115°C +90°C 4 A 250V ac Axial - 2.2mm 6mm 6mm - 0.53mm 38mm -
RS Stock No. 797-6064
Mfr. Part No.SF 094 R
BrandLimitor
£0.718
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. 797-6046
Mfr. Part No.SF 070 R
BrandLimitor
£0.718
Each (In a Pack of 10)
Units
+73°C +58°C 15 A 250V ac Axial - 4mm 8.5mm - - 1mm 18.5mm -
RS Stock No. 116-114
Mfr. Part No.SM 092 A0 2A
BrandLimitor
£0.89
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. 176-9407
Mfr. Part No.SM 146 A0
BrandLimitor
£0.55
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. 176-9378
Mfr. Part No.SM 110 A0
BrandLimitor
£0.824
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. 712-7304
Mfr. Part No.EYP1BF101
BrandPanasonic
£0.247
Each (In a Pack of 10)
Units
+102°C +75°C 1 A 250V ac Axial - 2.2mm 6mm 6mm - 0.53mm 38mm -
RS Stock No. 176-9384
Mfr. Part No.SM 126 A0
BrandLimitor
£0.716
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. 797-6061
Mfr. Part No.SF 139 R
BrandLimitor
£0.642
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. 176-9182
Mfr. Part No.P82 110 05100
BrandLimitor
£3.56
Each
Units
+110°C - 2.5 A 250V ac Radial - - 8mm 17.5mm 4mm 0.51mm 100mm -
RS Stock No. 124-5061
Mfr. Part No.A4-5AF
BrandLimitor
£0.82
Each (In a Pack of 5)
Units
+130°C +90°C 5 A 250V ac Radial A-5A-F - 8mm 6.6mm 2.6mm 0.6mm - -
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