HPS, timers and power cuts???

Hi.
Very soon i am going to be running a 5 of 6 plant grow that i am only going to be able to check once every week or two. I plan to use an auto-waterer but thats not what I'm here for. I will be growing in my attic. My house is very prone to power cuts. I will be having a 600watt Digital ballast HPS on a mechanical timer (12/12). My question is, how will power cuts effect this? Power is usually back with in an hour or so, will it mess up the timer or the ballast or bulb? Can the plants handle this disturbance?

Thanks

get a digital timer if you can with battery backup that way when the power comes back on you havent messed up the light schedule. the plants wont worry about darkness during light hours but light during dark hours is not good