Sorry, there I must disagree. In 50-cycle current the electrons move only cm or even mm. What travels at light speeds (and in fact the speed of light in the metal, which is only a fraction of the speed in vacum) is not the particles, but the electron waves. In other words the conduction of electricity is a wave effect, a consequence of quantum dynamics.

That wave motion is how electric current travels even in DC devices. However, though DC electrons don't travel all that fast either, they do travel further, and of course, the higher the voltage the faster conduction electrons do travel. It is again just the waves that travel at the more or less constant speed of light in the metal with its high refractive index (implying low light speed).

However, there is a non-quantum analogy that you might find helps you visualise the process. Suppose you have a long tray crowded with snooker balls in contact; you want to send a signal along the tray. You give a nearby ball at your end a smart rap. It travels hardly at all, and not particularly fast, but in a fraction of a second a ball flies off the other end of the tray.

Does that help?

Cheers,

Jon

Sorry again; finger trouble! Any one who can delete this copy, please do!