Ground fault circuit interrupter using frequency recognition and measurement

A wiring device comprising:

• an interrupting device electrically connecting one or more line terminals to one or more load terminals when the interrupting device is in a reset condition and disconnecting the line terminals from the load terminals when the interrupting device is in a tripped condition;
• a fault detection circuit configured to detect a fault condition and generate a fault detection signal in response to detecting the fault condition, the fault detection signal being provided to the interrupting device to place the interrupting device in the tripped condition;
• and
• a testing circuit configured to,
• determine a frequency of an input voltage at the one or more line terminals,
• determine whether the frequency of the input voltage is within a predetermined range, and
• when the frequency is within the predetermined range, perform at least one selected from a group consisting of a first test of the interrupting device at a first period of the frequency, and a second test of the fault detection circuit at a second period of the frequency.