122 defines how to size the equipment grounding conductor (EGC) in an electrical circuit. The National Electrical Code (NEC) provides clear guidelines for ground wire sizing through Table 250. 122. Underground wire sizing is very different from indoor runs, as underground circuits tend to run much longer, which makes voltage drop a major concern. Since voltage drop is an issue, the solution is to. This fact sheet explains how to apply the requirements shown in AS/NZS 3012:2019 Electrical installations – construction and demolition sites (AS/NZS 3012:2019), which is called up as a mandatory standard by section 163 of the Work Health and Safety Regulation 2025 (WHS Regulation).