A time current curve (TCC) plots the interrupting time of an overcurrent device based on a given current level. These curves are provided by the manufacturers of electrical overcurrent interrupting devices, such as fuses and circuit breakers. These curves are part of the product acceptance testing required by Underwriters Laboratories (UL) and other rating agencies. The shape of the curves is dictated by both the physical construction of the device as well as the settings selected in the case of adjustable circuit breakers.