Refer to the partial cable layout for a receptacle shown in Figure 128.122. When 14 AWG AC cables (without insulated ground) are installed, what is the smallest box listed below that can be used? The box contains the duplex receptacle and Circuits B9-11 feed the outlets. Cable connectors are external.

Refer to the partial cable layout for a receptacle shown in Figure 128.122. When 14 AWG AC cables (without insulated ground) are installed, what is the smallest box listed below that can be used? The box contains the duplex receptacle and Circuits B9-11 feed the outlets. Cable connectors are external.

• A. 3" × 2" × 2 1/4" metal switch box
• B. 4" × 2 1/8" × 2 1/8" metal device box
• C. 3" × 2" × 3 1/2" metal switch box
• D. 3 3/4" × 2" × 3 1/2" metal masonry box

Answer: (D)

Box fill is determined by counting every conductor that originates outside the box and is terminated or spliced inside, plus allowances for the equipment grounding conductors and the device itself. For 14 AWG, each counted conductor requires 2.0 in³ of space. Grounding conductors, no matter how many, count as one conductor total. A mounted receptacle (the yoke) also adds one conductor to the fill. External clamps are not counted here. In this layout there are four 14/2 cables entering the box (circuits B9-11 plus the through feed). Each cable provides a hot and a neutral, giving eight current-carrying conductors. All grounds are present but count as one conductor. Two pigtails are used to connect the receptacle to the splices (one hot, one neutral). The receptacle’s mounting strap counts as one conductor. Total conductors: 8 + 1 + 2 + 1 = 12. Required volume = 12 × 2.0 = 24 in³. Among the choices, the metal masonry box provides 26.25 in³, which is the smallest that meets or exceeds the 24 in³ requirement. The other options are too small to meet the box-fill need.

Box fill is determined by counting every conductor that originates outside the box and is terminated or spliced inside, plus allowances for the equipment grounding conductors and the device itself. For 14 AWG, each counted conductor requires 2.0 in³ of space. Grounding conductors, no matter how many, count as one conductor total. A mounted receptacle (the yoke) also adds one conductor to the fill. External clamps are not counted here.

In this layout there are four 14/2 cables entering the box (circuits B9-11 plus the through feed). Each cable provides a hot and a neutral, giving eight current-carrying conductors. All grounds are present but count as one conductor. Two pigtails are used to connect the receptacle to the splices (one hot, one neutral). The receptacle’s mounting strap counts as one conductor.

Total conductors: 8 + 1 + 2 + 1 = 12. Required volume = 12 × 2.0 = 24 in³.

Among the choices, the metal masonry box provides 26.25 in³, which is the smallest that meets or exceeds the 24 in³ requirement. The other options are too small to meet the box-fill need.