What safety equipment must be in place for excavations deeper than 20 feet?

For excavations deeper than 20 feet, it is essential to have a professional engineer's design for protective systems in place. This requirement stems from the increased risk associated with deeper excavations, including potential cave-ins, which can pose significant hazards to workers. A professional engineer's design ensures that appropriate protective measures, such as shoring, shielding, or sloping, are employed to safeguard workers in the excavation area. Their expertise is crucial for assessing site-specific conditions and designing effective protective systems tailored to the excavation's unique characteristics.

The other options, while they might relate to general safety practices, do not meet the specific regulatory requirements for deeper excavations. Safety helmets and goggles, backup alarms, and having a designated observer are important safety considerations, but they do not address the critical need for engineered protective systems required by safety standards for deeper excavations.