To obtain limb leads, electrodes are placed on the right and left arms and the left leg forming a triangle.
Each lead consists of a pair of electrodes, one is always positive and one is always negative, so they are sometimes called bipolar limb leads.
- The right arm is always negative.
- The left leg is always positive.
- The right arm is positive or negative depending on which lead we are talking about.
Lead I is horizontal with the outstretched arms. The right arm is always negative, making the left arm positive.
Lead II is diagonal and downward with the right arm, which always negative, and the left leg, which is always positive.
Lead III is diagonal and downward with the left leg, which is always positive, and the left arm, making the left arm negative.