Which of the following is not a safety equipment item required in drainage excavation?

Quality control charts are not considered safety equipment for drainage excavation. Instead, these charts are tools used for monitoring and controlling the quality of processes and outputs in various industries, ensuring that the work meets specified standards. In the context of drainage excavation, safety equipment is focused on protecting workers and ensuring a safe working environment.

Ladders, barriers, and dewatering pumps play crucial roles in safety. Ladders provide safe access to elevated areas, barriers prevent unauthorized access to hazardous zones, and dewatering pumps help manage groundwater to reduce the risk of accidents related to flooding or instability in the excavation sites. Each of these items serves a practical function directly correlated to the safety and efficiency of drainage excavation work, unlike quality control charts.