Different water testing meters specialize on certain aspects of water safety, so take that into consideration when choosing your tool. Here are some important details for P3 Electricity Usage Monitor. Includes: OPERATING VOLTAGE: 115 VAC MAX VOLTAGE: 125 VAC MAX CURRENT: 15 AMPS DIMENSIONS: 5-1/8 H X 2-3/8 W X 1-5/8 D Operating.