Do-It-Youself Possibility

[aschiou]

I am a pretty handy home owner, currently considering taking on the task of installing my own low voltage landscape lights. I'd appreciate any suggestions on the products, installation techniques to achieve a professional result. Obviously the fixtures may vary depending on my design. I'm more curious about the transformer. How to minimize voltage drop? Wiring layout("T" layout or "I" layout or "O" layout. I've also heard about the star layout using a hub). Appreciate any suggestions or tips on these issues. Thanks!

Allan

[sitelights]

Allan, I preface what I write by stating that I do not have the usual (mostly hidden) disdain for amateurs or do-it-yourselfers in this endeavor. Outdoor lighting is knowable and achievable to a very high level by those who approach it on the basis of inquiry and creativity. As with any other design/build project, what you must first determine is the level of quality you wish to maintain. As an example, (in general terms) do you want a "30 year roof" or copper downspouts, etc. or is your goal short-term?

My advice on the topics you mention are to first select the level of quality and stick to it. If budget considerations drive your project, you can always take the modular approach: put in place a quality "infrastructure" and then add to that. Purchase a transformer that exceeds your initial requirements by 100% (if you are contemplating a 150w system, buy a 300w unit, and so on); size your low voltage main cable generously (10/2 rather than 12/2 or 14/2); purchase metal fixtures (aluminum, copper or brass) that utilize halogen lamps (MR-16, MR-11 or bi-pin types); plan your system for the shortest possible cable runs.

As a rule-of-thumb, you cannot go more than a short distance before you encounter "voltage drop" (see other posts on this site for details) but you can minimize this problem by using "T" or "hub" or "looped" (the "O" configuration where you return to the transformer and connect in parallel maintaining polarity). My goal is to use the least amount of low voltage cable to reach the fixtures but depending on the layout of the system this is an open question. You should avoid straight runs over, say, 50' since voltage diminishes between the first and last lamp.

Each lighting project presents its own constraints and so there is no easy answer to your questions. If you can visualize (and this is an over- simplification) the low voltage energy as an irrigation system, with water volume and pressure as voltage and amps) then you can estimate the problem: low voltage is "low pressure/high volume" (12 volts in a large 10 gauge "pipe"). If you want the current to "flow" you need a large diameter pipe but each fixture bleeds off a certain amount of "water", so the pressure (and volume) drops in relation to the "nozzle" (which is the wattage of the lamp) at each spray point. What you need in this example is a good pump (transformer), large diameter pipes (cable) and minimum nozzle size (low watt lamps) to achieve a high performance system.

You should always assume that 20w will do the job but be able to increase to 35w or 50w and still stay within the designed output of the transformer in terms of total lamp load (see other posts for details). If you keep the low voltage cable runs as short as practicable and the load on the transformer well within its design limits you should be able to design and install a high performance system that meets your needs with the lowest possible energy costs.

Consider using a number of transformers in a large sytem to minimize cable runs. Good luck.

[aschiou]

Thanks for the timely response. I saw your post in a different thread on the recommended transformer. You mentioned something about the one made by ACME Electric. I don't know if it could be acquired directly by a home owner. My local electric shops carry the ones made by Hadco Lighting or Kichler. Are they good enough to last 30-year? Thanks!

[sitelights]

I am not a fan of either Kichler or Hadco transformers. The Acme T-79105SR/SL is a 500w unit and as such it does not comply with UL1838 which limits the maximum load on the secondary to 25 amps or 300w. What you need is a transformer that complies with UL 1838 and has a control system to operate the lamps from dusk to timed off. This is best accomplished using a photocell/timer combination. See my post under "control systems". I highly recommend (and will detail at a later date in a post to "product reviews") a transformer available at <http://www.escortlighting.com> as their TR600SSDIGI (dual 300w with 12, 13, 14v outputs); a 300w unit is also available with a mechanical timer. The DIGI designation incorporates the Grasslin control described in the "control systems" post. Escort Lighting also crafts very high quality copper fixtures and you can order on-line from their extensive and detailed site.