Which of the following precautions should be taken to prevent falls into an open excavation at night?

To prevent falls into an open excavation at night, providing lights and barriers is crucial. This approach ensures that the area around the excavation is well-illuminated, making it visible and reducing the chances of accidents. Adequate lighting allows workers and anyone near the site to see potential hazards, while barriers such as guardrails or fencing physically prevent individuals from inadvertently stepping into the excavation.

Signage alone is insufficient for nighttime safety because it does not provide any physical protection and may go unnoticed in low-light conditions. Covering the excavation with a steel sheet can be a good safety measure but does not address visibility and awareness, which are significant at night. Temporary backfilling can improve safety by reducing the open excavation but is not a standalone precaution and may not be practical for all situations, especially if immediate access is required.

Overall, the combination of effective lighting and barriers creates a safer environment by ensuring visibility and providing a physical barrier to prevent falls, making this approach the most effective in safeguarding against accidents during nighttime work near open excavations.