Why do some 240 volt devices need a neutral?

[Aaron Fude]

The way I see it, the current flows from one conductor to the other? So what's the neutral for? The only thing I can think of is perhaps these devices have several independent parts in them and some of those parts are 120 volts...

Thanks,

Aaron

[Stormin Mormon]

Some 220 VAC devices have a clock, circuit board, or some other sub assembly which is 110 VAC.

[stan]

. Trolling? Well; for example: Cooking stoves. The various ones we've had (three or four countries) vary somewhat. And only in 3 wire plus ground North American - Mexico 115 - 0 - 115 volt wiring practice.

Buy typically our present cooking stove has 230 volt elements and 230 volt oven heater/broiler etc. But the timer clock on this current one is (IIRC) I115 volt. Also there is a 115 volt light bulb in the oven controlled by a switch on the stove and a 115 volt 'convenience' outlet. Can't remember on this stove if that outlet is controlled by the timer; but sometimes they are. And it occasioanally makes a convenient place to plug in something heavy like a 1500 watt electric kettle or fry pan. On the other hand our 230 volt electric hot water heater does NOT need a neutral for anything I can think of.

[Aaron Fude]

Thanks for all the responses, but now I have a follow up question.

So some devices (A) need neutral and some (B) don't. Then I would guess that plugs on (B) should be a "special case" of those on (A). Meaning that plugs on (B) should be pluggable into outlets with a neutral. But unless I am mistaken, that is not the case. Why not? Or am I mistaken?

Thanks again,

Aaron

[EXT]

There are 4 prong plugs and recepticals for 240 volt with neutral, and there are 3 prong plugs and recepticals for 240 volt without neutral, they also vary in configuration depending on the amperage and if they are locking.

[RBM]

As others have said, if a 240 volt device requires a neutral, it uses 120 volts for some part of it. With the exception of older electric ranges and cooking equipment, any 240 volt device that requires a neutral would typically be hard wired or furnished with a 4 wire outlet and cord

[Bob]

It's not so much the age of the appliance as it is the age and wiring of the building that determines whether a 240 volt range or dryer has a 3 or 4 wire cord. The appliances are typically sold without cords for that reason. It also helps keep the advertised price down. If a 3 wire cord is needed, the neutral terminal on the appliance is bonded to the frame.

[RBM]

My point is that only ranges and cooking equipment are exceptions