Low Voltage or Line Voltage Lighting - How to Choose?

Wow! Electricity in Salt Lake. What an advancement! (I'm from Utah so I have poetic license.)

Line Voltage vs Low Voltage isn't really the best selection criteria. What you should be doing is selecting the fixtures/lamps based upon what you want to achive from a lighting design criteria. Most lamp colors are available both ways. In the ideal world, you'd want all lamps to be 6500 Kelvin but that's not likely to happen outside of RGB LEDs or dimming fluorescent lamps (they are also the only lamps which maintain color temperature when dimmed.)

"Buzzing" can be a consideration; however, using quality transformers (not necessarily 'expensive') and staying away from cheap, poor quality dimmers will prevent that issue. It is also worth pointing out it is more often the filament in the lamp which creates the buzz.

I went with low voltage puck lights due to space constraints. Due to duct work in my soffits, there isnt enough clearance for cans. I bought a 250w magnetic transformer for around $100 so i could dim them with my Grafik Eye. Im pretty sure with a magnetic transformer you could use most other 'standard' dimmers also. The transformer does buzz very slightly, but only when dimming. I built an enclosure for it out of 3/4" plywood and now I cant hear it at all, ever. I know the instructions said not to enclose it, but it has a fair amount of air space around it and it doesn't ever get very warm, probably because Im not drawing anywhere near its rated wattage. Cost wise, for me it was actually slightly cheaper to use the low voltage pucks. Originally i was going to use wall sconces, that would have been around $200 for the room. 10 low voltage puck lights and a transformer came in at around $150

1. i could be wrong, but i think pretty much anything with a built in transformer is going to be of the electronic variety. This is why I went with a separate transformer so I could use a magnetic one.

2. Electronic and magnetic transformers use different methods of dimming a light. I dont recall all the technical aspect of it though. Basically, if you use something like a grafik eye or standard dimmer switch, you cant just plug in an electronic transformer. You'd need and Electronic low voltage interface. This is not required for a magnetic transformer. The ELVI for a grafik eye was about the same cost as a magnetic transformer when I looked. If your not considering a grafik eye, this may not be important to you.

3. I didnt research this much and just used 12 gauge outdoor low voltage wiring. It stated on the package that it was to be used for certain distance of a run. Its also thicker than what came with the lights originally, but that was intended to be for a shorter run. The 12 gauge wire was reasonably cheap too. Keep in mind that with some low voltage systems, like my puck lights, the wiring is not to be permanently enclosed in a wall. this may vary depending on the fixture and wiring used. My wiring will be accessible through removable panels in the soffits.

4. dimmer goes in before the transformer. however, some low voltage lighting kits have built in dimming capabilities, but it cannot be controlled from something like a grafik eye or standard wall switch.

5. with a magnetic transformer, pretty much any standard dimmer switch should be fine. or use with a grafik eye. other autmated lighting systems like insteon might work too.

with an electronic transformer, i believe you need a dimmer designed for it or a special interface adapter.

6. i dont have much experience with track lighting, sorry. But Id say the same points regarding dimming a magnetic vs electronic transformer still stand.

I should also clarify. The primary reason I went with low voltage lighting was due to space constraints. My low voltage puck lights are only an inch thick. If not for that, Im sure I would have saved myself the trouble and went with line voltage as there are fewer issues to consider, especially when dimming.

Be very careful when designing with remote transformers on LV 12VDC systems. Gauge is a very, very big factor. You cannot wire like a normal line voltage ckt.

We have 123 lights fittings in our place (some have 2 globes). All low voltage, in the 3 years we've been here I have replaced 4 bulbs. They use GE Constant Color Globes.

Spend the money upfront and forget about them.

Oh and nearly every fitting is hooked up to a dimmer and they're all silent

Tech Lighting has a wire size table here.

12 volt 300 watt:
5 ft = 10 ga.
6-15 ft = 6 ga.
16-20 ft = 4 ga.
21-40 ft = 1 ga.
41-60 ft = 1/0 ga.
61-90 ft = 3/0 ga.

That assumes THHN wire and 3% voltage drop.

Those are some big wires. Landscape wire is not rated for in-wall use.

The trick is to home run each 50w fixture so you can use normal gauges and get decent distances. Star config instead of daisy chain.

Not familiar with them. Link?

Yep, the globes not the actual fittings. I cant seem to access those links.

3 things with lights:
- Fitting
- Globes
- Transformers

Poor fittings will cause problems between the globe and the transformer, regardless of how good the other parts are.

I think Dennis mentioned that you just need good quality transformers, I cant recommend on for you as in Australia the best thing is called a "possum" which is a local product.

The GE Globes we use wont change colour as they heat up, this is a common point of failure in cheap globes. Problems with the filaments etc.

Best of luck with it.

I meant the fixtures. But I didn't notice before you were in AU so nevermind

Well if you're ever planning on a move , speak with Tovo Lighting - superb products and even better people

and where is the most common and code approved location to mount the power supply for low voltage lighting systems?

are y'all putting them in the;
soffit
A/V rack
within a hidden electrical panel

My 12V transformer (and my Lutron Dimmers as well) is inside my soffit. My soffit has a fabric bottom and I have a matching fabric covered access panel that works like a drop ceiling tile to get to it. In other theaters I work on I'd say the more common place is either individual transformers located with the fixture(s), or a common transformer loated in an equipment closet or adjoining utility room. You have to be careful with LV wiring lengths though, they are a big factor you need to consider. FOr similar wattage requirements, due to the low voltage, the amperage is much higher and wire losses are significant.

Edit: I see I mentioned that before but can't hurt to repeat.