Meter Mod III. Main Breaker Modules. Main Breaker Single-Phase, Three-Wire 120/240 Vac with Arc Reduction Means. The main breaker in this section has an arc reduction means that satisfies the requirement of NEC 2014 Section 240.87. Single-Phase Mains have a neutral, A-Phase, B-Phase, and Ground, and may be connected to Three-Phase horizontal bus stacks. However, output is only single-phase. All Mains are required to be center feed only when the main circuit breaker rating is larger than the horizontal bus amperage rating. Main ampere rating: 1600 amps. IC rating (max): 100 KAIC. Bottom feed.