When sizing branch-circuit conductors and overcurrent protection for diagnostic equipment in health care facilities, the minimum percentage of the equipment's momentary ampacity allowed is?

• A. 50%
• B. 25%
• C. 75%
• D. 100%

Answer: (A)

The key idea is balancing startup inrush with ongoing protection when sizing for diagnostic equipment in health care facilities. Momentary ampacity is the current the equipment can handle for brief spikes during power-up or testing. If you sized the branch circuit to carry the full momentary ampacity, you’d risk unnecessary wiring and protection ratings, and if you undersize too much you’d clamp down on startup current or cause nuisance trips. Using half of the equipment’s momentary ampacity gives enough headroom for those short-duration surges while keeping the conductors and overcurrent protection within safe limits for normal operation. Higher percentages would not provide adequate surge margin, and lower percentages would make startup unreliable, so 50% is the appropriate, balanced choice.