A supply-side bonding jumper of the wire type used for this purpose must be sized per Table 250. 16 (B) provides volume allowances to be used when calculating the number of 18 AWG through 6 AWG conductors permitted in a box. 16 (B) (1) requires each conductor that originates outside the box and terminates or is spliced within the box to be counted once, and each. If using panelboards for service equipment, provide each one with a main bonding jumper to connect the service neutral conductor to the panelboard's metal frame [408. 66 for services with. Choosing the right wire size is critical for electrical safety and code compliance. This comprehensive guide walks you through NEC requirements, ampacity calculations, and real-world considerations that every electrician needs to master. 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. Practice good wiring: secure.