What is the first step to ensure a refrigeration unit won’t start while undergoing repairs?

The first step to ensure a refrigeration unit won’t start while undergoing repairs is to secure and tag the electrical circuit. This is a critical safety measure that prevents accidental energization of the system during maintenance. By securing and tagging the electrical circuit, you are effectively communicating to all personnel that the unit is under repair, and it should not be turned on until repairs are complete and the tag is removed.

While closing the main valve, draining the refrigerant, and turning off the thermostat are important safety and operational procedures as well, they do not provide the same immediate level of protection against the risk of the unit starting up unexpectedly. Closing the main valve can help prevent refrigerant leakage, and draining the refrigerant is essential for certain repair types but doesn't directly stop electrical activation. Turning off the thermostat can avoid the call for cooling, but it doesn’t ensure that power to the unit remains disconnected.

Therefore, securing and tagging the electrical circuit is the most effective first step to ensure safety when working on refrigeration units.