Undetected insulation breakdown in energized low-voltage electrical networks poses severe risks of electric shock, equipment damage, and electrical fires. Standard overcurrent devices operate reactively, tripping only after a hard fault or short circuit occurs. This paper presents the design and simulation of a low-cost, continuous Insulation Monitoring Device (IMD) tailored for energized single phase 220V AC systems. The hardware architecture interfaces directly with active line conductors and protective earth through a high-impedance resistor-capacitor coupling network to limit leakage currents to non-hazardous micro-ampere levels. To protect low voltage processing electronics from mains potential, the design incorporates an ISO124 precision isolation amplifier, establishing a capacitive barrier capable of handling up to 1500Vrms common-mode potential. The isolated signal is conditioned using an AD620 instrumentation amplifier (G = 11) and processed by an Arduino Uno microcontroller running a threshold-evaluation algorithm. Mathematical modeling demonstrates a linear dynamic response, mapping insulation resistance breakdown (500kΩ down to 15kΩ) to amplified output feedback (0.105V to 3.158 V). The system successfully flags the international standard warning threshold (1kΩ/V, or 220kΩ for a 220V system) and executes near-instantaneous digital outputs to actuate visual LEDs and an active buzzer. The proposed design establishes a reliable, galvanically isolated framework for transitioning low-voltage facilities from reactive breaker tripping to proactive, continuous insulation health monitoring