In a control apparatus, a voltage obtainer obtains an alternating-current voltage having a polarity across first and second alternating-current terminals. An overcurrent determiner determines whether a target current flowing through the first and second alternating-current terminals is in an overcurrent state. A controller alternately turns on a first set of first and fourth switches and a second set of second and third switches in accordance with the polarity of the alternating-current voltage. The controller changes a switching operation of at least one of the first to fourth switch being in an on state to thereby reduce the target current flowing through the first and second alternating-current terminals upon determination that the target current flowing through the first and second alternating-current terminals is in the overcurrent state.