Final answer:
Job-built trench boxes are not allowed in construction.
Step-by-step explanation:
Actually, job-built trench boxes are not allowed in construction. Job-built trench boxes are made on site and typically do not meet the required safety standards. They may not be properly designed, constructed, or tested to ensure the safety of workers. Instead, pre-engineered trench boxes certified by a professional engineer should be used, as they are specifically designed to meet safety requirements and protect workers from cave-ins. Using job-built trench boxes puts workers at risk and violates Occupational Safety and Health Administration (OSHA) regulations.