lights not working

[Doug]

I have installed about 25-35 12v. lights a customer has bought at a lowes
store I installed the underground wiring, which consists of a series of # 10 wires from the 900w. transformer to junc.boxs and then a #12 to each indiviual light, i have put at the most 4-6 lights on a set of #10 wires the volt reading I get is 12 volts at each light, the problem i am having is some of the lights do not come on after about a week, but if i go around and just tap the fixture the light will come on, the bulbs are securley in the base and all connections are tight,I have racked my brain on this one but i just cant figure it out? any advice will help me a lot? the fixtures the customer bought are not the cheapest lights, but i am sure they are not the top of the line either. also how long should a new bulb last?

[sitelights]

Check the posts "lamp socket comments" in the Lamps...Forum. It may be useful to search the archive which contains access to all of the threads on a topic of interest. This is at the bottom right of the home page: "archive".

Sounds like cheap sockets to me.

[Paul]

I have a feeling that it's those high quality Malibu fixture's sockets. It would cost more to replace the sockets than the fixtures are worth.

[JC Lighting]

See my post 1-15-2007 "Possible Filament Problem".

Jim C.

[SteveP]

Sounds like a perfect storm. Certainly cheap sockets, probably cheap lamps. I'm also wondering if you're getting an accurate meter reading at the fixture. If you're not using a relatively expensive meter, or one calibrated to 12V then your reading could be off be as much as one volt.

Having said that, the scenario you describe is usually caused by a break in the filament. Tapping the fixture causes the filament to fuse together temporarily, when the fixture is powered off, the filament cools and contracts opening the gap again. In many cases this gap is visible, you can look at the filament with a magnifier and see it.