low voltage lights

[albaran]

When we moved into the house, there were professionaly installed low voltage lights outside of the garage. They were 35 watt par 36 (that is the bulb style) in wells along the house. I couldn't find similar replacements at Home Depot so I put in the Malibu 25 watt bulbs that fit. The Malibu stuff is plastic and has been burning out after a few months. The orignal bulbs were glass. Is this because the voltage may be higher than 12 in the professional installations? I know that some of these are 15 volts to compensate for longer runs. The Malibu stuff isn't exactly cheap (about $10 a bulb).

 

[r_olson_06]

When we moved into the house, there were professionaly installed low voltage lights outside of the garage. They were 35 watt par 36 (that is the bulb style) in wells along the house. I couldn't find similar replacements at Home Depot so I put in the Malibu 25 watt bulbs that fit. The Malibu stuff is plastic and has been burning out after a few months. The orignal bulbs were glass. Is this because the voltage may be higher than 12 in the professional installations? I know that some of these are 15 volts to compensate for longer runs. The Malibu stuff isn't exactly cheap (about $10 a bulb).

Usually over voltage is the cause of short bulb life. Check it with a meter and see what you are running for voltage. If there is 15v on a 12v bulb that is more than likely the cause. Now the problem would be trying to find a bulb with a little bit higher rated voltage. Also if the power supply has a "tappable transformer" You may be able to change the voltage slightly lower to reduce this problem.

 

[Greatbear]

Using smaller wattage bulbs in low voltage installations will often result in a higher voltage in the system from lessened voltage drop and other losses if the number of lamps remains the same. Many systems are fixed in the number of lamps that are used and the wattage per lamp. Better systems have a switch or tap that can be changed to adjust the voltage. When individual lamps burn out and aren't promptly replaced, the higher voltage on the remaining ones shortens their lives.