Double volume allowance is required for which scenario?

• A. One or more wiring devices on one yoke
• B. Internal cable clamps
• C. Fixture studs
• D. Grounding conductors

Answer: (A)

In box-fill calculations, extra space is needed when more than one wiring device shares the same mounting yoke. If one or more devices are on a single yoke, you must apply a double volume allowance to those devices because the yoke and devices occupy additional space inside the box. That’s why this scenario is the correct choice: when multiple devices share one yoke, you count extra conductor equivalents to reflect the physical space they take.

Internal cable clamps are counted as one conductor, grounding conductors together count as one conductor, and fixture studs are hardware rather than devices on a yoke, so they don’t require this double allowance.