Return to the Lighting Forum | Post a Follow-Up

 o
Entire room of low voltage recessed cans w/separate transformer?

Posted by dfw17 (My Page) on
Fri, Nov 5, 10 at 22:33

Hi,

Five years after finishing our kitchen remodel - which involved moving a washer + dryer to the basement - my DH is finally finishing that "new" laundry room. Dry wall is up, and he is ready to do lighting and the drop ceiling. I want recessed cans for general lighting, plus a few specifically located over a clothes-folding/hobby table. There's also 1 wall of upper/lower cabinets (incl sink) that will need some lighting. I would be okay if these were also properly placed recessed lighting. (Ideally, we would do undercabinet lighting, but I'm trying to keep this project straight-forward so we finally get it finished!)

My DH wants to install all low voltage recessed lights connected back to one single transformer (which would be connected to the one line circuit that comes into the room, and is already connected to a switch). When I visited our local lighting store, I was told that the largest diameter low voltage recessed lights (without built-in transformers) available are 3" and they would not be powerful enough to light the entire room, plus they couldn't be reliably installed in a drop ceiling. (They would eventually fall out.)

My husband says hogwash. Help educate me please! (BTW, the room is approx 8 ft x 11 ft).

Thanks,
DJ


Follow-Up Postings:

 o
RE: Entire room of low voltage recessed cans w/separate transform

Most low voltage recessed lights (LED included) will not supply enough lighting, unless you have quite a number (eg - 1 per ft or more).

Assuming an entire LV setup with 1 or more transformers
You will need to calculate the number of lights needed, the length of low voltage wiring, wire gauge, number of transformers.

DC voltage lines suffer more voltage drop than AC lines. That's also the main reason why line voltage is AC.

If you're using halogen lights, the wires need to be fairly thick due to the amount of current drawn.

The above configuration is highly impractical.
There are LV recessed lights that have the transformer built into each fixture. (3" - 4")

http://www.pegasuslighting.com/4inch-12v-recessed-lighting-housing-remodel-75w.html.

There is a danger that the light fixture itself could fall if fastened to ceiling tile. However, if the drop ceiling is standard sheetrock that is properly supported and fastened, you will not have a problem.

Some alternatives - T8 fluorescent lighting or LED ceiling tiles.


 o
RE: Entire room of low voltage recessed cans w/separate transform

davidtay,

Thanks for the education! I've got a little better direction for my weekend "research".

--DJ


 o
RE: Entire room of low voltage recessed cans w/separate transform

I am not a fan of low voltage cans but some people like them. The lv cans we have installed each have their own transformer that are fed with regular 120v circuits. Most of the time when we have installed these cans it is used to downlight art. Davidtay gave you some great advice.


 o
RE: Entire room of low voltage recessed cans w/separate transform

Why are you using cans in a work area?

They are about the poorest general lighting source around.


 o
RE: Entire room of low voltage recessed cans w/separate transform

DC voltage lines suffer more voltage drop than AC lines. That's also the main reason why line voltage is AC.

To be clear, the issue is the voltage, not whether it's AC or DC. The lower the voltage, the more current you need to achieve a given wattage. Higher current means more losses in the wiring.

Low voltage is not practical for room lighting unless you are powering fluorescents (RV or PV system fixtures) or LEDs. Even then it is not the better choice.


 o
RE: Entire room of low voltage recessed cans w/separate transform

"DC voltage lines suffer more voltage drop than AC lines. That's also the main reason why line voltage is AC."

Nothing to do with AC or DC, strictly a voltage issue.
Low voltage lighting uses much higher currents, AC or DC.

75 watts at 120 V is only 0.625 amps.
At 12 V it takes 6.25 amps.
At 24 V 3.125 amps.

Voltage drop in circuits is current times wire resistance.
Losing a volt in a 120 V system is hardly anything (the acceptable voltage variation on 120 V is +/-10%).

Losing a volt in a 12 V system is a real problem.

If the lines were 120 V DC there would be no issue.


 o
RE: Entire room of low voltage recessed cans w/separate transform

I'm surprised to read the posts above where it was said that low voltage is not a good choice for general lighting. We use small low voltage "bullet" cans (each has its own transformer) in our kitchen. We used the GE perfect color bulbs which you can get in a choice of spreads -- we got the wide spread 55 degree bulbs. I am really liking the light -- I prefer focused light to overall ambient light and these do give plenty of light. I know these are generally used as focused spots for art work, but if you get the wide spreads they work well as general lighting. The color is also good. Be aware that you will need special electronic dimmers if you want dimmers and that they have a max load per dimmer.


 o
RE: Entire room of low voltage recessed cans w/separate transform

"We use small low voltage "bullet" cans (each has its own transformer) in our kitchen. "

"I prefer focused light to overall ambient light..."

Since you are not looking for general lighting but task lighting cans are more useful.

It takes a LOT of cans to generate general lighting for a working room like a kitchen.

Even with a "55 degree bulb" the coverage is going to be spots of light, and to eliminate harsh shadows when only one light source is on an area you need to make sure the beams overlap at each location.


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!


Return to the Lighting Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.


Learn more about in-text links on this page here