Service heads shall have conductors of different potential brought out through separately ___ openings.

• A. bushed
• B. sized
• C. isolated
• D. grounded

Answer: (A)

Separating conductors of different potential in service equipment requires bringing each conductor through its own insulating opening. This is accomplished with bushed openings—openings fitted with insulating bushings that isolate and protect conductors as they pass through a metal enclosure. Using separate bushings prevents arcing between conductors at different potentials and maintains the enclosure’s insulation and integrity.

Sized openings don’t provide insulation or separation beyond a larger hole, while isolated openings and grounded openings aren’t standard terms for the protective insulation needed here. The key idea is using insulating bushings to keep conductors of different potentials electrically and mechanically separated.