won't work..
as soon as one contactor is switched on, the other one can't be as the switch contacts are broken.. ( and the contactor is latched on.. )
you'd need an off switch..
There is no frustration proof way of preventing both showers being used at the same time. The closest you could get would be a system using water flow switches, but still not frustration proof.
Crazy idea - give it up now.
What about a complex system of interlocks which prevents simultaneous access to the two bathrooms?
So both doors are on automatic door closers and as soon as a door is opened this music http://www.youtube.com/watch?v=ShGrtA17mSg&feature=related is blasted around the house for the duration of the shower.
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