Final answer:
Generally, a unit switch with a marked 'Off' position can be an acceptable disconnect for an appliance, but it must meet certain conditions stipulated by the National Electrical Code and may need to comply with additional local code requirements.
Step-by-step explanation:
The statement "The unit switch on an appliance is an acceptable disconnect for an appliance as long as the switch has a marked 'Off' position" is generally True, but with caveats. National Electrical Code (NEC) specifications detail when a unit switch can serve as a disconnect.
A switch is an acceptable disconnecting means if it is within sight of the appliance, is capable of being locked in the off position (if required), and has a marked off position that complies with NEC 404.8(A) and 430.109(A)(1). It's essential, however, to ensure that the switch meets local code requirements, which can differ from the NEC and may have additional criteria.