A method comprising: a processor driving a ground offset voltage of a notification appliance circuit (100, 200, 210) to a first level; while the ground offset voltage is at the first level, the processor measuring a first voltage on a first terminal of the notification appliance circuit; while the ground offset voltage is at the first level, the processor measuring a second voltage on a second terminal of the notification appliance circuit; the processor driving the ground offset voltage of the notification appliance circuit (100, 200, 210) to a second level; while the ground offset voltage is at the second level, the processor measuring a third voltage on the first terminal of the notification appliance circuit; while the ground offset voltage is at the second level, the processor measuring a fourth voltage on the second terminal of the notification appliance circuit (100, 200, 210); the processor determining a first voltage drop between the fourth voltage and the second voltage; the processor determining a second voltage drop between the third voltage and the first voltage; and when a magnitude of the first voltage drop or the second voltage drop is greater than a first predetermined value defined as 1% of a supervision voltage applied to the first terminal, the processor determining that a state of the notification appliance circuit (100, 200, 210) is ground faulted, wherein the first terminal includes a high side terminal of the notification appliance circuit (100, 200, 210), and wherein the second terminal includes a low side terminal of the notification appliance circuit (100, 200, 210). a processor driving a ground offset voltage of a notification appliance circuit (100, 200, 210) to a first level; while the ground offset voltage is at the first level, the processor measuring a first voltage on a first terminal of the notification appliance circuit; while the ground offset voltage is at the first level, the processor measuring a second voltage on a second terminal of the notification appliance circuit; the processor driving the ground offset voltage of the notification appliance circuit (100, 200, 210) to a second level; while the ground offset voltage is at the second level, the processor measuring a third voltage on the first terminal of the notification appliance circuit; while the ground offset voltage is at the second level, the processor measuring a fourth voltage on the second terminal of the notification appliance circuit (100, 200, 210); the processor determining a first voltage drop between the fourth voltage and the second voltage; the processor determining a second voltage drop between the third voltage and the first voltage; and when a magnitude of the first voltage drop or the second voltage drop is greater than a first predetermined value defined as 1% of a supervision voltage applied to the first terminal, the processor determining that a state of the notification appliance circuit (100, 200, 210) is ground faulted, wherein the first terminal includes a high side terminal of the notification appliance circuit (100, 200, 210), and wherein the second terminal includes a low side terminal of the notification appliance circuit (100, 200, 210).