Flat-top underfloor raceways over 4 in. but not over 8 in. wide must be covered with concrete to a minimum depth of what?

Flat-top underfloor raceways that are wider than 4 inches but not exceeding 8 inches must be covered with concrete to a minimum depth of 1 inch to ensure effective protection and stability. This requirement is set to safeguard the raceways from physical damage and to maintain the integrity of the systems housed within them. Adequate coverage helps in preventing any impacts or stressors from affecting the raceway and the components contained within.

Proper depth is critical; if the coverage were to be less than 1 inch, there might not be enough protection against accidental impacts or heavy loads. Hence, ensuring that the concrete coverage meets or exceeds this specified depth is essential for compliance with safety standards and codes in electrical installations.