There is disclosed an electrical connection unit for a refrigeration system comprising: a container defining an interior for containing electrical circuitry, the container having an external port configured to couple with an external connector; a closure moveable relative to the container between a closed configuration in which access to the interior is prevented, and an open configuration in which access to the interior is permitted. The closure has a locking portion defining a connector opening for receiving the connector, configured so that movement of the closure to the open configuration is prevented by interlocking engagement of the connector and the closure. There is also disclosed an associated method of coupling or decoupling a connector and an electrical connection unit.