How far must each raceway be supported within an outlet box for the box to be considered supported?

For a box to be considered supported in accordance with the National Electrical Code, each raceway must be supported at intervals that ensure the box is securely held in place. The requirement specifies that the raceway must be supported within 18 inches of the box. This ensures that the conductors do not bear the weight of the raceway and that there's adequate support to prevent damage and potential hazards.

Choosing 18 inches aligns with the NEC guidelines, which emphasize not just the structural integrity of the installation but also safety in accessibility and maintenance of the electrical system. This standard helps to ensure that any pull or strain from the raceway does not impact the outlet box, which could lead to unsafe conditions over time.