What is a critical factor when using metal raceways in electrical systems?

When using metal raceways in electrical systems, grounding is a critical factor. Metal raceways are conductive pathways designed to protect electrical wires and provide a secure environment for them. Grounding these raceways is essential because it helps to ensure safety by providing a low-resistance path for fault currents. This reduces the risk of electric shock, fire hazards, and other electrical incidents that may occur if a fault develops.

Grounding also protects the equipment and enhances the overall reliability of the electrical system by minimizing electromagnetic interference. It's crucial that metal raceways be properly grounded according to the National Electrical Code (NEC) and local electrical codes to ensure compliance and safety.

The other choices do not address the critical requirements needed for safe and effective installation of metal raceways in electrical systems. For instance, while painting may be relevant to corrosion prevention, it is not a fundamental requirement like grounding. Similarly, stating that metal raceways cannot be used at all is incorrect because they are quite common in electrical installations, and indicating that they should be used for all wiring overlooks specific installation guidelines and suitability for different types of wiring methods.