Three-Wire Watt Meter Connections
This arrangement requires only two heavy gage wires to carry the negative lead current and so is best for remote testing and monitoring. The third, plus, wire can be lighter gage (e.g. 20 gage or heavier) as it only carries the small current required to run the meter itself.
The three wire hookup also allows higher current operation as the heat from power dissipated by high current in the plus wire is no longer present.
Bottom most diagram shows use of reset button with the auxiliary power connector cable.
See our Meter Links page for a handy wire resistance and voltage drop calculator.
Please note that many other meter uses and arrangements are possible.
The "Watt's Up" Watt meter's User's Manual has more details and safety precautions.
A battery or other voltage limiting device must be connected between the watt meter's red and black leads anytime the load is connected or disconnected. The battery prevents inductive loads causing damage to the meter.
Three-wire Meter Connections