160 for example the lowest average current measured for a degraded sheath 160 edge hole g at 12 5 ma is over six times higher than the highest average current measured for an uncompromised element i e good d a partial electrical schematic partial block diagram for another construction of the control circuit 200 a used for controlling the heating element 140 is shown in fig4 similar to the construction shown in fig3 the control circuit 200 a includes the microcontroller 205 the thermostat switch 210 a the voltage measurement circuit 220 and the current measurement circuit 225 however for the construction of the control circuit in fig4 the first leg 202 a of the circuit 200 a is connected to 120 vac or 240 vac and the second leg 203 a of the control circuit 200 is connected to ground as further shown in fig4 the double pole thermostat switch 210 a is electrically connected between the current measurement circuit 225 and 120 vac or 240 vac the operation of the control circuit 200 a for fig4 is similar to the control circuit 200 for fig3 table 2 demonstrates a comparison between a heating element 140 initially having no apertures and the element 140 having an aperture at the edge of the element.