Most of your Grow lamps have diffrent ways of telling you there going bad. There not like a house lamp 75% of them wont just go out  and never come back on. Some will ack as if there overheating and shut down and then come back on when there cool that means the inner tube that holds the gases is leaking and will eventually fail. Some will pulse in and out like a soft strobe light That means the bulb will get to the shutting down stage sooner or later. Dont worry if your lamps start strobing it doesnt mean its going to fail the next day I have tested some lamps that ran over 3 to 5 months before shutting down. Others you will notice a change or rate in growth nether color change or time length is taking longer then your last crop and no changes were made to feeding or lighting.

My System wont light after being unpluged or power go's out?

Note: if your system comes  unpluged or power go's out and you go to plug your system or turn on and the bulb doesnt come back on right away give it about 20 to 30 minutes to let the bulb cool down it should fire right up most high watt bulbs wont ignite if there to hot you have to wait for the inner tube to cool down a little.You can leave your system on and once that bulb cools down it will light.  understand bulbs get to about 250 to 350 degress.