Which statement best contrasts standby power with emergency power in LV systems?

• A. Standby power is the primary source for life safety systems only; emergency power is used for all nonessential loads.
• B. Standby powers loads during outages with automatic transfer; emergency power is dedicated to safety and critical systems with defined transfer criteria.
• C. Standby power is a backup generator; emergency power refers to UPS only.
• D. Standby power and emergency power are identical except for color.

Answer: (B)

Standby power is meant to keep nonessential building loads running when normal power fails, with automatic transfer to an alternate source so equipment that isn’t critical can continue operating during an outage. Emergency power, on the other hand, is reserved for safety-critical or life-safety systems, and it follows defined transfer criteria and sequencing to ensure those essential functions (like exit lighting, fire alarms, and life-safety systems) remain powered.

That distinction is what makes this option the best. It correctly pairs standby with automatic transfer for nonessential loads, and emergency with safety-critical loads plus explicit transfer criteria. The other statements mix up which loads belong to standby versus emergency, oversimplify what emergency power includes, or treat the two as the same thing.