A set of electrodes suitable for being attached to the skin of an animal or human being at locations normally used for attaching single-lead electrodes with a single sensor point. The electrodes of the set of electrodes have at least three sensors arranged to define two linearly independent directions, which allows sensing corresponding electrical potential differences in the two directions. Signals representing sensed potential differences can be transmitted wirelessly or via conductors to a processing apparatus for being transformed into electrical potentials that approximate traditional potentials obtained with wired single-sensor electrodes. A method is also presented.