ECG machine Lead Placement Method  : WILSON Standard Leads  : Wilson leads system, proposed by Wilson, is the central terminal connection leads system. Taken European Standard as an example, its connection method is as follows :  1. Electrode R ---right arm 2. Electrode L ---left arm 3. Electrode N ---right leg (Earthing line) 4. Electrode F ---left leg 5. C1: Fourth intercostals space at right border of sternum 6. C2: Fourth intercostals space at left border of sternum 7. C3: Midpoint between V2 and V4 8. C4: Fifth intercostals space on left mid clavicular line 9. C5: Left anterior axillary line at the horizontal level of V4 10. C6: Left middle axillary line at the horizontal level of C4