Leaving the right amount of wire in an electrical box is crucial for safety and code compliance. Check for proper IP/NEMA ratings and material quality. Ensure safe placement: install in dry, accessible areas with good ventilation and at appropriate height (typically ~1. If they need to be placed outdoors, especially in high humidity, you must ensure their waterproofness. You may also want. At least 150 mm (6 in. ) of free conductor, measured from the point in the box where it emerges from its raceway or cable sheath, shall be left at each outlet, junction, and switch point for splices or the connection of luminaires or devices.