At this point, you're probably wondering why you bothered running four wires
to the subpanel, if all you're going to need is three. The answer is, so that
you can run 120V circuits off that subpanel, too -- they need the neutral,
even though the 240V circuits don't. Maybe you don't ever plan on putting any
120V circuits in that panel... but the next guy to own your home might.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

Yeah, i am. I understand the 120 volt thing. I think. So why does
240 volt not require a neutral? I thought everything
electric was based on supply (hot) and return (neutral). Ground was
only for when the **** hit the fan, and the power had to decide
between your body or the easier path to earth which was the green
wire.

Why is 240 different than 120 in that sense?

And why is it said that one should run 4 wire if its a 240 appliance?