Model railroads should run, or you just won’t enjoy the craft. Making them run though is another complicated – yet ultimately the most fun – aspect of model railroading.

Though the most train models run now on electricity, model railway engines long ago were powered by clockwork or gas such as propane, with big enough models having actual steam. Levers control the clockwork railway engine models, levers that got activated and deactivated as they pass around the tracks. Because old-fashioned model railway engines are typically made of metal, they are robust and heavy enough to set off control levers. When model railroads manufacturers, out of convenience shifted from metal materials to plastic materials while the scale grew smaller, the models became lighter making levers unworkable. With that, manufacturers also shifted to electric powered and clockwork models became thing of the past and are sought by model railroad collectors.

The common model railroad electronic is DC, though some popular manufacturers like Lionel and Märklin uses AC.

The three rail electrical system is a common implementation for older model railroad electronics. On the three rail model railroad electronic, the locomotive wheels rests on a metal track that has metal sleepers in it to provide and conducted power all though out the railroad system, just like one gigantic wiring. A third and separate middle rail exists running on the entire center of the tracks that provides power for the skid normally found under old locomotive designs. This is a peculiar model railroad electronic design at first glance, though if understood made clear sense as older model railroad electronics are hampered with insulation problems. Past model railroading designs were mostly made of metal, as modern hard plastic were yet to evolve. Tin models for train and metal tracks pose large short circuiting problems.

At present, with plastics affording accuracy to model railroad designs, model railroad electronics adopted the two-rail power designs, wherein both sides of the wheels were insulated from each other. This is the simplified and most efficient model railroad electronic, with each rail carrying the positive and negative supply of the DC charge (or if using AC model railroad electronics, the two sides).

Though the DC model railroad electronics are much more standardized, some prominent manufacturers exclusively use AC model railroad electronic system. Such as Lionel and Märklin who still uses AC power on a three-rail model railroad electronic system. Another model railroading manufacturer, American Flyer is another exclusion, but uses AC power on a two-rail model railroad electronic system.