Thermal cut-offs are safety devices that are used to protect circuits and equipment from overheating and potential fire hazards by shutting off electricity when temperatures get too high. They are usually mounted on the electrical component itself, such as the wiring or connection box. Thermal cut-offs will monitor and respond to changes in temperature, and when they detect a temperature that is outside of the predetermined range they will trigger a switch to shut off the electricity. Thermal cut-offs can be made from circuits, resistors, metal alloys, and semiconductors, but the most common are bimetallic strips. These are made out of two layers of different metals that will bend when exposed to heat, and the bending of the strip will trigger a switch to shut off the electricity flow.