Switch over to 220V light bulbs.  Thieves won't come back when they find
     the bulbs won't work at home. Probably only a few thieves.

     Detecting burned out bulbs requires a monitor.  Measuring current and
     sounding alarm with each sudden drop may work for small number of bulbs per
     circuit.  Looking for 5% change (20 bulb string) is easy.  Trying to detect
     1% spike (100 bulbs) in environment with lightning, power surges, RFI.....
     That could get challenging.
     Except for expense, you could put a current monitor in each lamp fixture.
     Poll each lamp via X-10 type communication.




     ---------------
     That's it, I have to come up with a solution. On small airports, people
     steal light bulbs from the runway. How to prevent (detect) it ? And maybe
     detect burn-out bulbs as well ?
     Thanks in advance.
     Pedro.