A system to measure alternating current, AC, voltage in an insulated conductor, the system comprising: a conductive sensor positionable adjacent the insulated conductor without galvanically contacting the conductor, wherein the conductive sensor capacitively couples with the insulated conductor; a variable capacitance subsystem which includes a first capacitance subsystem node and a second capacitance subsystem node, the first capacitance subsystem node electrically coupled to the conductive sensor, and the first capacitance subsystem node and the second capacitance subsystem node having a capacitance therebetween which is selectively variable between at least a first capacitance value and a second capacitance value, the second capacitance value being different from the first capacitance value; a voltage measurement subsystem which in operation detects a voltage between the first capacitance subsystem node and the second capacitance subsystem node; at least one nontransitory processor-readable storage medium that stores at least one of processor-executable instructions or data; and at least one processor communicatively coupled to the at least one nontransitory processor-readable storage medium, and in operation, in response to execution of the processor-executable instructions or data, the at least one processor: causes the variable capacitance subsystem to have the first capacitance value between the first capacitance subsystem node and the second capacitance subsystem node; causes the voltage measurement subsystem to detect a first voltage between the first capacitance subsystem node and the second capacitance subsystem node; causes the variable capacitance subsystem to have the second capacitance value between the first capacitance subsystem node and the second capacitance subsystem node; causes the voltage measurement subsystem to detect a second voltage between the first capacitance subsystem node and the second capacitance subsystem node; and determines the AC voltage in the insulated conductor based at least in part on the detected first voltage and the detected second voltage a conductive sensor positionable adjacent the insulated conductor without galvanically contacting the conductor, wherein the conductive sensor capacitively couples with the insulated conductor; a variable capacitance subsystem which includes a first capacitance subsystem node and a second capacitance subsystem node, the first capacitance subsystem node electrically coupled to the conductive sensor, and the first capacitance subsystem node and the second capacitance subsystem node having a capacitance therebetween which is selectively variable between at least a first capacitance value and a second capacitance value, the second capacitance value being different from the first capacitance value; a voltage measurement subsystem which in operation detects a voltage between the first capacitance subsystem node and the second capacitance subsystem node; at least one nontransitory processor-readable storage medium that stores at least one of processor-executable instructions or data; and at least one processor communicatively coupled to the at least one nontransitory processor-readable storage medium, and in operation, in response to execution of the processor-executable instructions or data, the at least one processor: causes the variable capacitance subsystem to have the first capacitance value between the first capacitance subsystem node and the second capacitance subsystem node; causes the voltage measurement subsystem to detect a first voltage between the first capacitance subsystem node and the second capacitance subsystem node; causes the variable capacitance subsystem to have the second capacitance value between the first capacitance subsystem node and the second capacitance subsystem node; causes the voltage measurement subsystem to detect a second voltage between the first capacitance subsystem node and the second capacitance subsystem node; and determines the AC voltage in the insulated conductor based at least in part on the detected first voltage and the detected second voltage causes the variable capacitance subsystem to have the first capacitance value between the first capacitance subsystem node and the second capacitance subsystem node; causes the voltage measurement subsystem to detect a first voltage between the first capacitance subsystem node and the second capacitance subsystem node; causes the variable capacitance subsystem to have the second capacitance value between the first capacitance subsystem node and the second capacitance subsystem node; causes the voltage measurement subsystem to detect a second voltage between the first capacitance subsystem node and the second capacitance subsystem node; and determines the AC voltage in the insulated conductor based at least in part on the detected first voltage and the detected second voltage