Non-load driven fault monitor for electrical circuits

A method of testing for faults in an electrical circuit, the circuit having a load, the method comprising the steps of:

• providing a fault monitor, having:
• a power supply connected in series with a resistor;
• a connection for connecting to the circuit with the load in parallel with the resistor;
• a voltage sensor connectcd in series with the resistor;
• and
• switching means for opening and closing the connection between the power supply and the resistor and load;
• providing a test switching means connected in series with the resistor and in parallel with the current sensor, in sequence after the first transistor;
• closing the test switching means;
• determining whether voltage is sensed by the voltage sensor, thereby determining whether current is flowing through the load;
• connecting the fault monitor to the circuit with the load in parallel with the resistor;
• passing a current through the circuit and fault monitor;
• and
• detecting the resulting voltage at the voltage sensor, thereby determining whether the total resistance provided by the load indicates a failure within the load and also determining a number of elements having faults within the load based on the difference between the resulting voltage and an expected voltage.