The present disclosure relates to a method of monitoring switching by an on-load tap changer (OLTC) (1) from a first contact (3a) to a second contact (3b) of a transformer winding (2). The method comprises measuring a voltage of the transformer. The method also comprises measuring a temperature of the OLTC. The method also comprises, based on the measured voltage and temperature, determining whether the switching from the first contact to the second contact has been successful.