In article , "Existential Angst" wrote:

Is a 3-wire bx cable leaving a panel *necessarily* an edison-type deal?

No. It could supply an appliance that has both 240V and 120V loads. Examples
include electric dryers (240V heating elements, 120V motor and controls) and
electric stoves (240V heating elements, 120V controls).


Do the two hots *always* have to be connected to separate phases?

Well, no, not *always* -- one of them could be connected to nothing, I
suppose.

But if they're both connected, then yes, absolutely.

You can't get 240V unless they're on opposite legs of the service. And if
they're on the same leg, then the current in the neutral could be as much as
twice what it's rated for -- which is a potential fire hazard.