Abstract: A voltage substitution device and method of use thereof, wherein the voltage substitution device may include at least two voltage meter modules, a variable DC to DC converter, at least two leads, a switch, a variable resistor and at least two power supplies. One power supply provides power to the voltage meter modules, while the other power supply provides power for the variable DC to DC converter. The leads may be attached to alarm sensor wires, and one voltage meter module displays the voltage across the sensor wires. The output voltage of the variable DC to DC converter may be displayed on the second voltage meter module. The variable resistor may be adjusted to vary the output voltage of the DC to DC converter to match the voltage across the sensor wires. Once the voltages are matched, the switch may be closed to place the output voltage of the DC to DC converter onto the leads and in parallel with the sensor wires.