Contactors are used for high power applications. They allow a lower voltage and current to switch a much higher power circuit, so they are generally larger and more heavy-duty than control relays, enabling them to switch higher power loads on and off for many thousands of cycles Standard control relays typically have contact ratings of 10A or less at 250Vac or less. Contactors, on the other hand, carry much higher contact ratings up to many hundreds of amps, and are commonly rated for operation at 600Vac.