Final answer:
To ensure safety, doors, and access panels of resistance welding machines and control panels must be locked or secured to prevent unauthorized access to live parts, reducing the risk of electrical accidents.
Step-by-step explanation:
All doors and access panels of all resistance welding machines and control panels must be locked or secured to prevent access, by unauthorized persons, to live portions of the equipment. Resistance welding machines make use of significant electrical currents to generate heat and fuse materials. Due to the inherent electrical hazards, it is crucial that any potentially live parts are inaccessible to those who are not qualified or authorized to handle such equipment. By locking or securing access points, the risk of accidental contact with live electrical components is greatly reduced, thereby enhancing safety within the working environment.