Interior bonding/grounding conductors are made of which material by default, unless another material is specified?

• A. Stranded Copper
• B. Solid Copper
• C. Aluminum
• D. Steel

Answer: (A)

Stranded copper is chosen by default for interior bonding and grounding conductors. The flexibility of a stranded conductor makes it much easier to route, bend, and terminate inside equipment rooms and around racks and cabinets, reducing stress on terminations and preventing damage from movement or rearrangements. Copper also offers excellent conductivity and corrosion resistance, which are essential for reliable grounding connections and compatibility with standard hardware and terminations.

Solid copper, while conductive, is less forgiving in tight interior spaces and can be harder to bend without fatigue. Aluminum can be used in some applications but poses issues with connections to copper hardware, potential galvanic corrosion, and higher resistance. Steel conducts poorly and is not used for grounding conductors.