A clamp electrode apparatus comprises first and second clamps which are mechanically connected to form a single integrated device and arranged side by side such that a first edge of the first clamp faces a second edge of the second clamp. A channel is defined between the first and second edges for aligning a visible mark feature of a limb, such as a malleolus or ulnar head, within the opening or channel when the first and second clamps clamp the limb. When the limb is clamped with the clamp electrode apparatus multiple times, the visible mark feature can be aligned with reference to the channel. Thus, electrodes attached to the clamps contact generally the same locations even if the clamp electrode apparatus is removed after each measurement and is not kept on the limb throughout the multiple measurements.