Originally Posted by jerichorick
At your transfer sw, open the cover and carefully measure the voltage on the terminals. From the shore cord connections you should see 240VAC black to red and 120VAC black OR red to white or ground.
If the shore power checks correctly measure the voltage in the same manner on the feed going to the power panel. If the voltage check is not identical there is a problem in the switch. Unplug the shore power and tighten all of the connections in the transfer switch, clean the contacts on the plug and lube with anti-oxide grease. If no loose connections are found or a problem with the plug the transfer switch needs to be replaced.
Voltage is 120 in the transfer box at both switches on the power side. Leg 1-2-3 on bottom switch has 120 volt on back side of switch, Leg 4-5-6 on top switch has zero volts on the back side. A transformer box feeding into the transfer switch box is humming but I can't determine which of the 4 transformers (2 signal, 2 ring type instrument) are humming. Is this normal? Hate to buy a new transfer box if it is a small transformer prior to the transfer switches.