I picked up some work at a 2600 acre mountain developement here in western North Carolina. It's basically lots of small stuff that their maintenance can't or doesn't want to do(repair fixtures, troublshoot photoeyes and timers, etc.) They are having a problem with some landscape lights continually blowing bulbs. They are the Malibu brand with the 180watt/timer combo. There are 8 11 watt lamps on the circuit.

Are the bulbs really bad or just developing a bad contact with the socket. These Malibu things are pretty much junk if it is the same stuff they sell at Home Depot.
What is the actual voltage?

Longshot could be....incorrect bulbs. The wedge base bulbs could be the incorrect voltage.

Have to agree here, I have these at my house. If it is not a bad connection with the bulb contacts, it can also be the wire clamp connection, which is usually buried under ground. The wire clamp is also plastic and a pain to crimp tightly.

How close are the bulbs to the timer. I beleieve they need to be a certain distance away or the voltage is too high. The output voltage is actually higher to compensate for voltage drop.

"They" (Intermatic) also recommend that the transformer be loaded to at least 50% of its rating, or an overvoltage condition will result.

You might try a 121 watt xfrmr.
http://www.amazon.com/Intermatic-ML121RT-Malibu-Voltage-121-Watt/dp/B0002YTPL4

Intermatic also manufactures an 88 watt transformer if you think it's more suited to your needs
http://www.amazon.com/Malibu-ML88T-88-Watt-Ground-Shield/dp/B0000DG57B/ref=pd_cp_hi_2
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Also, look at the bad bulbs. If they are black, then the bulb envelop cracked, mostly due to water, and let air in.If so check for water intrusion I agree most of these are made real cheap. Robert

The bulbs are black. Some of the ones that still work have turned black. I agree that they are cheap. I am getting 12 v at the socket. I will talk to them about upgrading the fixtures.