SEKI ST-12 Bimetal Thermal Switch

SEKI’s ST-12 thermal cut-out uses a snap-action, bimetal blade that operates at a pre-determined set-point calibrated at the factory.  The ST-12 can be pre-set at any temperature from 60°C to 150°C in steps of 5K.  After activation, the blade snaps shut again once the ambient temperature has sufficiently cooled down.

The open-frame design of the ST-12 means that it is particularly well suited for monitoring air-flow temperatures and can respond rapidly to an over-temperature condition.  This is vital in such appliances as hair-driers and hand-driers where a stalled fan can cause the heating element to glow red hot in a short period of time.

The SEKI ST-12 is very competitive in its basic form and special terminal options or lead-wires can be added for high-volume applications.



  • Hair Dryers
  • Hand Dryers
  • Fan Heaters
  • Convector Heaters
  • Popcorn Machines



  • Snap Action with Automatic Reset
  • Very Fast Heat Response
  • Contact Rating: 13A/250V AC (10,000 cycles)
  • Temperature Settings: From 60℃ to 150℃
  • Safety Certification: UL/cUL, VDE, CQC, CMJ, KC
Bimetal thermal cut-out for household appliances ST-12 Drawing