Wiring requirements of distribution box Upper incoming line, lower outgoing line, main circuit on the left, control circuit on the right, horizontal and vertical. The exposed laying can take the sheath line, or through the pipe and trunking. In this guide, we'll break down everything you need to know to install a distribution box correctly and confidently. Choose the right box based on environment (indoor/outdoor), load capacity, and durability. Check for proper IP/NEMA ratings and material quality. Whether you're a professional or a DIY enthusiast, understanding the correct procedure can prevent accidents and ensure optimal performance. A distribution box, also known as a.