For electric only C, here’s a rule of thumb: (C = circuit ), electrical fires. (A = ash), things that burn that produce ash. (B = barrel) fuels contained within barrels. It is not necessary to cut off the mains power supply for most electrical fires, unless it is the mains. In their initial stage, electrical fires are often low in heat and then spread to other classes of fire.
Multi-type extinguishers are generally better than specific ones. For example, ABC or ABCD is more effective than A or B or C. A panel fire is easy to extinguish, while a circuit box fire is difficult to extinguish.