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 includes measuring a voltage of the transformer. The method also includes measuring a temperature of the OLTC. The method also includes, based on the measured voltage and temperature, determining whether the switching from the first contact to the second contact has been successful.