Low Voltage Lighting

[woodduder]

This seems the best section of forum for my question.

What is the advantage of low voltage lighting?

The reason I ask is because I was in BIG ORANGE yesterday and was looking at the remodel recessed lighting, 4", incandescent, 50 watt.

They carry a fixture that uses a GU-10 lamp which is 50 watt and operates at 120 volt.

It is a very simple and lightweight item to install.

They also carry a fixture that uses an MR-16 lamp which is 50 watt and operates at 12 volt with a heavy, bulky transformer attached to each one which seems to me to be just another part that would go bad eventually.

Both use a lamp with a 50 watt output. Do they not use the same amount of VA at their input?

Seems crazy to install a LOW VOLTAGE fixture if they do use the same VA.

Help me understand. Thanks

 

[mhulbert]

Typically, low voltage lighting has better control and distribution of the light (ie more light gets out of the reflector and fixure). The reason for this is that the low voltage allows you to have a smaller filament. The closer a filament is to a "point source" (a tiny dot), the better control you have over the light, and the higher reflector efficiency you will realize.

I have not use the line voltage MR16's. I have not had any projects that have a need for it. That said, I asked a person that does a lot of lighting at my supply house about it a while back, and I know they were having some problems with the sockets burning up. However, BK lighting makes some fixures that accept it, and they are typically of the highest quality and tested before they release a product, so I have to imagine it's workable. Another downside is the lack of wattages and beam spreads available in the line voltage unit. With all that said, we need to compare these units on the basis of lighting performance.

These aren't "official" lamp spec sheets, but are test results from BK lighting. I tried to find official data from the lamp manufacturer for the line voltage mr16, but I can't find that particular bulb in their catalog.
Compare lamps with identical wattage and beam spread:
LowVoltage MR16: http://www.bklighting.com/cimages/nw-75.pdf
LineVoltage MR16: http://www.bklighting.com/cimages/nw-85.pdf
As you can see, by looking at the Center Beam Candlepower, the low voltage MR16 is quite better (brighter)than the equal line voltage lamp.

What they don't tell you is that cheaper low voltage fixures typically only deliver 11 volts to the lamps, and this gives them a pretty big performance hit. However, if you have a spec grade fixture (or properly wired landscape lighting), you will realize how bright a low voltage light can be for a given wattage. Often, a 20 or 35W low voltage MR16 will do the same duty as a 50W PAR20 or PAR 30. Another option is the IR versions of lamps, where a 37W lamp gives you the light output of a 50W conventional lamp. These save enough electricity over their lives to pay for themselves.

Perhaps somebody here will chime in with real world experience using the line voltage MR16's. I'd be curious to hear their results.

Mike

 

[Sierrasparky]

I've used them , they work fine. Have not had problems. If variety of lamp choices is not a problem then I would go with them.
If you are using them for general illumination Low voltage may be a waste of money.
I have used the most expensive color corrected Ge precise lamps in the past. Then customer replaces a burned out lamp with a cheap replacement. I visit their house and see those multicolored halos at the edge of the beamspread to combat that I usually supply a few replacements.

 

[mhulbert]

I usually provide a full case of each lamp type (if it's a big project like new construction or a big remodel). This at least keeps it looking good for quite a while. If possible, I'll try to not use more than 2-3 lamp types within the project, so there is less to stock and a you have a less confused owner.

Glad to hear the line voltage MR16's are working out. As you said, if it's just for general illumination, they are probably fine. But really, using MR16's for gen illumination takes a lot more cans and time than using larger cans with PAR's or a halogen A-lamp reflector, or ideally, decorative fixtures and sconces, and use less ceiling acne overall. It's best to save the MR16's for artwork and accents.

 

[dbuckley]

I hate line voltage MR16s, but that view may be coloured (sorry - bad pun) by my line voiltage being twice yours. Your mains voltage MR16s may be altogether less objectionable than the one I see.

In addition to the filament size versus optical performance issue already coloured, the colour temperature is different; the mains versions are more yellow than halogen white.