Electrical Safety, Code Administration, and Inspection Requirements
Codes and authority
Article 90 defines scope, and 90.4 gives the authority having jurisdiction (AHJ) responsibility for interpretation and approval. Installations must be approved, and the AHJ may waive or modify requirements. Article 110 covers general requirements: listed equipment, workmanlike execution (110.12), and proper terminations (110.14). Permits and inspections follow local adoption of the Code.
Working space
Table 110.26(A)(1) requires depth of 36, 42, or 48 inches depending on voltage and condition; width is at least 30 inches or the width of the equipment, whichever is greater; height is 6.5 ft. The space must be clear, not used for storage, and the dedicated equipment space above and below must be kept clear. Service disconnecting means must be capable of being locked open (110.25).
Safe work
NFPA 70E governs arc flash and shock protection: incident energy analysis, arc-flash boundaries, PPE, approach boundaries, and energized work permits. Lockout/tagout, verification of de-energization, and test-before-touch are core practices.
Worked example
A 480 V panel requires working space depth of 42 inches under condition 2 and 48 inches under condition 3, width of 30 inches or the panel width, and 6.5 ft of height. A storage box placed in that space is a violation even if the panel can still be opened.