A method of monitoring joint and contact conditions in an automatic transfer switch includes: collecting electrical signals at a plurality of measurement locations associated with a plurality of power sources and a load over a predetermined period, the electrical signals including voltages and load current; obtaining deltas between source voltages and corresponding load voltage measured at the measurement locations over the predetermined period; comparing the deltas with thresholds obtained during healthy condition; determining that the deltas fall outside of the thresholds; and in response to determining that the deltas fall outside of the threshold, transmitting an alert to a user, the alert indicating a detection of one or more failure modes at the measurement locations.