Q:

Low power switch with microcontroller

I'm designing a light switch that will be controlled by a uC. The problem is that the uC will be connected to a coin battery cell (3,3v) and he can't waste energy in the switch circuit. So what would be a design that would have a low power consumption in the activation switch?
The light will be connected to the grid and it will draw a maximum of 10A.

A:

There are such things as Latching, Sequence and Impulse Relays.  Most if not all such devices are designed to only require power when changing states.
There is also a 2 coil latching relay.  I believe you momentarily energize one coil to turn it on and the other to turn it off. 

