The box is drawn at one size only, to show the wiring; the box size is your answer. Every conductor in each cable stays in the box, and each cable jacket ends at the box clamp. Each tag names the cable and its size; the dots show the conductors in that cable: black, white, red, green (insulated bond) and a copper ring (bare bond). On a receptacle, white goes to the silver screw on the left and black or red to the brass screw on the right. Drawn for clarity, not to scale.
Usage
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