Final answer:
The correct option is C) When manually switched off.In an industrial setting, deep fat fryers are typically de-energized when manually switched off by an operator, not simply after a predetermined time frame or automatically.
Step-by-step explanation:
In an industrial setting, the power to the deep fat fryer will typically de-energize when manually switched off. It is crucial for safety and energy conservation to have control over when the equipment is active. While some machines may have automatic shut-off features after reaching a specific temperature for safety purposes, they do not generally de-energize after a set period such as 8 hours of continuous use, nor do they automatically turn off every 24 hours for maintenance. The maintenance schedule is dependent on the fryer's usage and the company's policies, and it is not typically linked to an automated power-down. Therefore, they are switched off manually by the operator or through a programmed mechanism that is in compliance with the company's operating procedures.
Additionally, the power to the fryer typically does not de-energize automatically after a specific duration of time (Option A). While it is possible to set timers to control the duration of operation, the fryer will continue to operate until manually switched off.
Similarly, the power to the fryer does not de-energize every 24 hours for maintenance (Option D). Instead, maintenance tasks are typically performed as part of a regular cleaning schedule and are not related to the power supply.