What is maintenance mode in BAS and how does it differ from run mode?

• A. Maintenance mode enables automatic control; run mode disables all alarms
• B. Run mode is normal operation with automatic control; maintenance mode allows technicians to override or disable controls for system service, often with restrictions and logging
• C. Maintenance mode permanently disables all actuators
• D. Run mode requires manual input for all setpoints

Answer: (B)

Maintenance mode in a BAS is a temporary operating state that lets technicians service equipment without the normal automatic controls fighting their work. In run mode, the system operates normally, using automatic control to maintain setpoints based on sensors, schedules, and logic.

When maintenance is needed, the system can enter maintenance mode to allow overrides or disabling of certain controls during service tasks. This mode is typically restricted, may be time-limited, and is logged so who made changes and what actions were taken can be reviewed. The goal is to enable safe, effective servicing without compromising safety or system integrity, while still keeping a clear audit trail.

Other options aren’t accurate because maintenance mode is not about turning automatic control off entirely or permanently disabling actuators, and run mode does not require manual input for all setpoints.