During a power cut, the cabinet starts to warm as heat leaks in through the walls and seals. Hold-over time depends on insulation thickness and quality, gasket condition, how full the cabinet is, the ambient temperature and how often it is opened. A full freezer holds over much better than a half-empty one, because the frozen product itself stores cold.
Chest freezers usually hold over better than upright cabinets, because cold air does not spill out when the lid is lifted and the top opening limits infiltration. Some specialised units add eutectic plates or cold packs, which freeze while power is on and absorb heat when it is off, extending hold-over for vaccines or ice cream.
Where power cuts are common, staff should know a simple rule: keep doors shut during an outage, check temperatures when power returns, and follow the business's food safety or pharma procedures for any stock that has been out of range. A data logger or alarm that records the excursion makes those decisions easier.