Industrial buildings depend on electrical services whose interruption can disable process protection, ventilation, communications, security and emergency response. Saudi Arabia's expanding industrial infrastructure therefore requires power continuity strategies that address both routine equipment faults and prolonged external disruptions. This review critically synthesises research published between 2020 and 2025 on redundant uninterruptible power supplies, automatic power transfer, standby generation and associated control systems. Sources were examined through a structured, topic-led integrative review and evaluated against failure independence, transfer behaviour, autonomy, maintainability and service restoration. The synthesis finds that additional equipment cannot guarantee resilience when redundancy shares batteries, switchgear, cooling, control logic or maintenance exposure. Furthermore, an automatic transfer switch normally introduces an interruption; genuinely interruption-sensitive loads require an appropriately configured online UPS or equivalent ride-through provision. A layered architecture is proposed in which independently protected load paths are coordinated with verified source-transfer sequences, conditioned battery capacity and tested emergency generation. The review extends infrastructure-scale resilience principles to facility-level electrical interfaces and identifies measurable acceptance criteria for industrial applications in Saudi Arabia. Evidence gaps include sparse local field performance records, limited joint modelling of transfer and battery failures, and insufficient validation under compound heat, dust and utility disturbances. These findings provide a design and assurance agenda rather than an assertion of measured performance at any particular site.