Landscape lighting...Solid or Stranded wire?

Well, I may be a bit late to ask this since I already ran the wiring and installed all the lights, but anyway, here's the dilemma.
I am installing a light fixture on top of each post on my deck railing. There are a total of ten posts, hence ten lights. Each fixture has three 12v light bulbs. Each light bulb is 18watt, push-turn (bayonette base, like car tail light bulbs), so each fixture is 54 watts. I ran 14 gauge solid romex (2 conductor plus ground), from the transformer and daisy-chained to each fixture. In other words, all fixtures are wired in series. I was carefull to observe the polarity at all fixtures.

Since total wattage is 540watts, I installed a 600 watt 110v-to-12v transformer to an outside GFCI outlet and connected the wire from the fixtures to the terminals on the transformer.

When I flipped the switch to energize the GFCI, all the lights worked but the bulbs are of different brightness: the fixture that is first in the series, or closest to the transformer was very bright, but the brightness of each subsequent fixture is stepped down, and in the last fixture the filament in the bulbs barely glows. Reversing the polarity at the transformer makes no difference.

Any thoughts???

 

the key issue is the conductor size and with low voltage luminaires the voltage drop is far much more sensitve than line voltage verison.

you should upsize the first half with either #12 or #10{ 4.0 or 6.0mm²} that useally take care the issue with voltage drop or split the circuit in half take 5 luminaries on one half and other 5 on other half and both meet at the low voltage transfomer { that one of few option you can go from there }

Merci,Marc

 

I already tried that too, but did not work. I removed the last 5 fixtures but I still get the same dimming effect. So if I have 2 sets of lights, with 5 fixtures in each, then I would still have the same problem, where not all 5 fixtures have the same brightness.

Another idea I had was to remove the transformer and just push 110v through the wires by using a dimmer switch and push very little current to see what happens.
Will the 12v bulbs blow out if I set the dimmer at the lowest setting? I have read that bulbs don't care if the current that is ran is either AC or DC.

 

You need to wire them in parallel not series. When they are in series the voltage drops after each light. By the time is gets to the last lamp the voltage is so low that the bulb barely glows.

You can not use a dimmer to control the voltage that much. You will just destroy the light bulbs (and maybe the fixtures.)

 

540 watts at 12 volts is 45 amps. Your wire is way undersized, and is a fire hazard. You also should not have used NM-B outside. Its only to be used in normally dry locations.