26 mm 2 (10 AWG) ground wire must be used, and in all other markets a 6 mm 2 must be used. Power from factory ground must be installed by a qualified electrician. Grounding of the units: Attach a ground wire from one of. The National Electrical Code (NEC) provides clear guidelines for ground wire sizing through Table 250. 122, but understanding how to apply these requirements correctly can make the difference between a safe installation and a costly code violation. The rule links the minimum size of the grounding conductor directly to the rating of the overcurrent protective device protecting the circuit, such as a circuit breaker or fuse. 122. Whether you're a seasoned pro or just starting out, this comprehensive guide will give you practical insights into proper grounding techniques, with a special focus on how selecting quality materials from a reliable building material supplier impacts your entire system's safety and longevity. This manual is applicable for low voltage AC and DC drive systems. Please enter a valid service size between 30 and 2000 amperes.