ASAHI US-603 Manual-Reset Cut-outs

The Asahi US-603 is a snap-action, manual reset 1/2″disc thermal cut-out.  When it reaches its pre-determined set-point, the bimetal disc snaps from concave to convex and opens the internal set of electrical contacts.  After a suitable period of time (and after checking/fixing the cause of why the US-603 operated), the reset button can be pushed to re-make the electrical circuit.

The bimetal disc used in the US-603 is specially formed to stop it from auto-resetting.  It can be calibrated to operate from 50°C to 160°C in one degree steps if required.  With opening tolerances as small as ±3K, it can be fine-tuned to closely protect the intended application whilst switching loads of up to 2.5kW.

This manual reset cut-out is available with a variety of terminations (4.8mm, 6.3mm solder) and orientations (vertical, horizontal and angled at 45 degrees).  A choice of fixing options from simple surface flanges to M3 (or M4 or M5) stud screw-in bases are possible.  Also various air flanges help to make the US-603 even more responsive in airflow sensing applications.

Suitable for large and small domestic appliances, electric heaters and industrial heating elements.


  • Water heaters
  • Domestic appliances
  • Electric heating elements
  • Amplifiers
  • Catering equipment


  • Range 50°C/160°C (T160 Rating)
  • Snap action contacts
  • Manual-reset operation only
  • Loads up to 10A/250VAC
  • VDE, UL and C-UL approvals
  • Various fixings available