Choose the type of electric system you will be monitoring. You need to choose a meter appropriate for your load. Usually, the electric system will match the load, but not always. For instance, you may have an apartment that only has lights and 120 volt appliances. If you are hooking it up to a standard electrical panel, you will have loads on both of the hot wires in a 3 wire, 120 volts to neutral, 240 volts line to line system, so you would choose the 3 wire system instead of a two wire system. But in a marina, you might have a 4 wire, three phase 208 volt wye system running down the docks with only two hot wires coming off to a 50 amp breaker and receptacle. The marina owner would choose the meter appropriate for his load, a 3 wire, 120 volt to neutral, 240 volt system.
Voltages - The voltages shown are the most common ones used. The meters actually have a fairly wide range of acceptable voltages so choose the voltage nearest your system. The voltage ranges are 90-140 volts, 200-250 volts, 250-300 volts. The wild leg on the Shenandoah meter can be in the range of 430-500 volts Contact the factory if you have any questions about this.
The Olympic meter does not fit nicely into this system. This meter has three current transformers and can measure a three phase system or a single 2 wire 120 volt system plus a separate 3 wire 120/240 volt single phase system. Do not use this meter to measure power at a house with 120 volt loads and 240 volt loads unless you need to keep track of those loads separately. The Yosemite meter is normally used for that application. Click here for more on the Olympic meter.