> Thicker wires will heat up less for a given amount of current, increasing the carrying capacity of the circuit. One solution to increasing the effective thickness of a conductor is to “bundle” several conductors a few inches apart from one another, allowing for a larger increase in current for less cost than a conductor that is simply double the size.<p>In power engineering at university we were taught that the separation of the wires within a conductor, to increase the effective diameter, is primarily about reducing the self-inductance rather than dissipating heat. From memory, it's along the lines that the separation effectively increases the diameter of the conductor, which in turn reduces the intensity of the magnetic field, reduces the self-inductance and allows more power transfer for a given voltage and current.<p>The article got it right in saying spacing the wires gives an increase in current for a given cross-section of conductor, but the main reason is reduced inductance rather than the reduction in resistance due to it running cooler. There will be some reduction in resistive losses due to cooler conductors, but the main gain is the reduction in reactive power, which otherwise causes current flow with no power transfer.