I have an interior Jack and Jill bathroom that is connected to two bedrooms. I'm trying to solve the problem of someone locking the other door when using the bathroom and then forgetting to unlock it before leaving.
Trying to come up with a solution, I thought of synchronizing the two locks via a light sensor. Light on, both doors lock. Light off, both doors unlock. Unfortunately, I'm unable to find a lock to achieve this.
Does a lock like this exist? What would be another viable solution to this problem?
Best Answer
DO NOT BUILD THIS PROJECT. It is not safe. I am leaving the description here for now to retain the comments.
For a safe version of the Jack&Jill bathroom project see my other answer, that begins with "I think I understand all the requirements:"
Shop for "Electric Bolt Locks (Fail Safe)". These sell for about $40 to $500 but you certainly don't need the expensive kind. They operate on 12VDC or 24VCD so you can wire them safely and easily. Install one on each door and control them both from a single switch inside the bathroom, so that both are locked or unlocked together.
To deal with the possibility of the locks somehow "failing secure" instead of "failing safe" you should get locks that also open with a key (or a pin -- thanks @Tim B), and you should place the transformer somewhere outside the bathroom.
You could use a switch near each door, either in a 3-way or a parallel circuit. The parallel seems less confusing because you can say "Both switches need to be down to get out of the bathroom."
Or if you really want to make the locks to operate with the light then you can just wire the transformer in parallel with the light fixture. Of course this will result in people occasionally thinking they are locked in the bathroom when they are not.
In any case make sure the locks themselves are wired in parallel.