Which of the following is NOT a common cause of electric shock?

Using labeled electrical equipment is not a common cause of electric shock because labeling is intended to inform users about the safe and proper use of electrical devices. Labeled equipment is typically designed to meet safety standards and regulations, which include instructions for safe operation, grounding requirements, and warnings about potential hazards. When used as directed, labeled equipment minimizes the risk of electric shock.

On the other hand, wet hands while touching electrical devices, wiring errors in installations, and using power tools without proper grounding are significant risks that can lead to electric shock. Wet conditions can increase conductivity, making it easier for electricity to flow through the body. Wiring errors, such as improperly connected wires or faulty connections, can create short circuits or unintended paths for electricity. Similarly, power tools that lack proper grounding can result in the user becoming a path for electrical current, leading to serious injuries. Therefore, it's essential to use labeled equipment correctly to avoid hazards.