Final answer:
Temporary power systems must be inspected and certified as safe before they are used to ensure the safety of all personnel and the integrity of the systems.
Step-by-step explanation:
When dealing with temporary power systems on a construction site or similar setting, these systems need to be inspected and certified as safe before they can be put into use. The correct answer to the question is a) Before use. This is to ensure the safety of all personnel and the integrity of the electrical systems. Safety is a critical aspect in all engineering fields, and particularly so when dealing with electrical systems. An inspection helps identify any potential hazards or deficiencies in the temporary power setup which could lead to accidents, fires, or electrical failures.