Low Voltage Lighting In Wall

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Old 02-01-10, 07:57 AM
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Low Voltage Lighting In Wall

I'm just about to have an electrician come in to complete the electrical portion of my kitchen remodel. He's going to wire for under cabinet lighting. They recommended puck lights, which I purchased, but I've done some research since then and I don't like what I'm reading. The pucks I bought are line voltage and are the plug-in type. I REALLY don't want him to wire outlets inside the cabinets... not even sure if it's code. I think I want to buy either the Kichler or SeaGull linear lighting systems. They seem to get great reviews. I have an issue with hiding the wire that will connect to the cabinets on either side of the sink. There's no way to hide them except running the wire in the wall. What are my options there? Any insight on my issue, or feedback on kichler/seagull linear systems in general, is most appreciated.

Thanks guys.
 
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Old 02-02-10, 03:26 PM
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I normally install the Seagull Ambiance low voltage undercabinet lighting. Unless you can find a way to mount a transformer low voltage may not be an option.

You can have the switched receptacles in the cabinets for the plug in lights by code. They cannot be on the 20 amp circuit for the kitchen receptacles. I would also not like to lose that much space in the cabinet.

Can you post a pic of your cabinets?
 
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Old 02-03-10, 09:57 AM
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Don't have them installed quite yet. I spoke to a local electronic wholesaler who carries the Ambiance line (The owner was an electrician for 30 years.) He claims that running the low voltage wire behind the drywall meets code in Pennsylvania. He said because it's low voltage there is less of a risk for fire. He also mentioned that the transformer can NOT be mounted behind the drywall. My plan, at his suggestion, is to run romex to the electronic dimmer, then to the transformer(s) in the basement (so I have easy access), then the output wires would be the low voltage stuff that would run to the lights. This entire string will be on it's own circuit. Also, I was planning on running 2 150w electronic transformers instead of 1 300w. I thought it would be easier to string 2 small runs through each half of the L-shaped layout instead of one large piece. Does this sound like a good plan?
 

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Old 02-03-10, 10:41 AM
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Sorry to disagree with your guy, the LV cable is not for use in the wall. Both the national electrical code and manufacturers instructions say no.

Run NM cable off the output of the transformer to the cabinet bottom and then switch to the LV cable in a junction box.

Voltage drop becomes an issue especially with 12 volt systems so you would want to run a larger cable size than normal. Ampacity will be 10x higher on the 12 volt system too. You want to keep the output cable length as short as possible to avoid dim lights at the end of the cable.
 
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Old 02-03-10, 10:48 AM
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What's NM cable... regular Romex? And could I use the Sea Gull splicer instead of a junction box? That stinks because I have to get past the kitchen window. There's nowhere to hide the cable but behind the wall. If I need to keep the runs shorter then maybe the 2 150w transformers instead of 1 300w is the way to go. That way I'd have 2 short runs instead of 1 large run?

Thanks for the help.
 
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Old 02-03-10, 02:26 PM
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You could run the cableing through the lower cabinets and then fish up.
 
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Old 02-03-10, 06:26 PM
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Originally Posted by Tolyn Ironhand View Post
You could run the cableing through the lower cabinets and then fish up.
I'd still have to go into the wall to fish it up to the upper cabinets. This is my "new" plan:
  1. Run the new circuit to the dimmer first
  2. From the dimmer I'll run romex to the 120v side of the transformer in the basement
  3. I'll splice 2 romex cables to the output wires on the 12v side of the transformer. The transformer is enclosed and can act as a junction box.
  4. Each of the output romex cables will be run in the wall and will feed a leg of the lights
  5. Where each romex cable exits the wall in the kitchen I'll connect them to the LV cable using the low profile sea gull "splicer" boxes
Sound right? Sorry... not trying to be thick... This is the first time I've worked with low voltage stuff and I just want to get it right.
 
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Old 02-03-10, 06:34 PM
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Your plan sounds fine.

Just be sure to pay attention to install the proper size NM cable for the installed ampacity.

NM= non metallic cable, which is commonly called by the brand name of Romex.
 
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Old 02-03-10, 06:38 PM
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Originally Posted by pcboss View Post
Your plan sounds fine.

Just be sure to pay attention to install the proper size NM cable for the installed ampacity.

NM= non metallic cable, which is commonly called by the brand name of Romex.
Cool, thanks. Gonna show my real ignorance here, but I have no clue what ampacity is... will do some reading I have leftover 14 and 12 gauge cable from my basement remodel. I would think 12 gauge would be large enough.
 
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Old 02-03-10, 07:43 PM
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Ampacity is similar to GPM. It is a measure of how much current is flowing.

The wire size needs to match or exceed the ampacities that will be imposed on it to prevent overheating and possible fires.

To figure ampacity divide the wattage by voltage.

600w / 120 volts = 5 amps
600w / 12 volts = 50 amps
 
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Old 02-04-10, 06:00 AM
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Ampacity is a term created by the NFPA meaning: The current in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.

Its the Ampere Capacity of the wire, so cleverly called Ampacity.
 
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Old 02-04-10, 11:17 AM
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Are DC and AC transformers interchangeable with the Ambiance system? I read that using an electronic DC transformer pretty much eliminates voltage drop but you still get all the benefits of it being electronic, ie, cooler, quieter, etc. If these will work I may go that route. I called Sea Gull support and, while they were very helpful, they of course told me that I NEEDED to use their transformers or it voids the UL listing. I wonder if that's really the case or they are they just want me to buy their gear? Since my runs will be at about 15' the DC transformer seems like a great idea. Thoughts?

Thanks again guys.
 
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Old 02-04-10, 11:49 AM
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I agree with what you heard from the Seagull rep.
 
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Old 02-05-10, 01:35 PM
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Holy cow. I didn't expect this solution to cost so much. My original solution was halogen puck lights: $100. My new solution is 25' of Sea Gull Ambiance LX with all parts and dimmer: $450 I guess you get what you pay for... or at least I hope
 
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Old 10-23-10, 03:43 PM
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more low voltage lighting wiring questions!

sorry to revive an older thread, but i have almost the exact same issue.

how did it go, sinTAKs? did the 'new' plan work out?

i am wondering if this will work:

1. run 12-2 romex (from a kitchen lighting circuit) up through the wall to a dimmer switch on the kitchen wall to control all my undercab LED task lights (5 cabinets with low voltage LED lamps totaling 45 watts).

2. from this switch, run 12-2 down through the wall to a transformer in the basement that we will mount in an accessible location.

3. from the transformer (as long as it has enough output knockouts i think this will be a 100W 24 volt dimming power supply from environmentallights.com), run 3 legs of 14-2 romex up through the walls to three openings in the kitchen walls where i will have to splice the 14-2 romex to the low voltage cable that connects to the light fixtures.

Q: how does this splice work? what kind of connectors are used? what kind of a cover plate? and is it code to have this low-voltage splice in a junction box in the wall? or does it have to be in/under the cabinet somewhere?

thanks for any help. i have wired my entire kitchen so far, and am getting hung up on this low voltage stuff!
 
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Old 10-23-10, 09:42 PM
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Originally Posted by sahric View Post
sorry to revive an older thread, but i have almost the exact same issue.

how did it go, sinTAKs? did the 'new' plan work out?

i am wondering if this will work:

1. run 12-2 romex (from a kitchen lighting circuit) up through the wall to a dimmer switch on the kitchen wall to control all my undercab LED task lights (5 cabinets with low voltage LED lamps totaling 45 watts).

2. from this switch, run 12-2 down through the wall to a transformer in the basement that we will mount in an accessible location.
Ok I have one question to ask ya how far is the transfomer to the LED luminaires you will be installing ? that may affect the voltage level including the LED { they can dimmed pretty good if not carefull }

3. from the transformer (as long as it has enough output knockouts i think this will be a 100W 24 volt dimming power supply from environmentallights.com), run 3 legs of 14-2 romex up through the walls to three openings in the kitchen walls where i will have to splice the 14-2 romex to the low voltage cable that connects to the light fixtures.
24 volt verison is not super senstive with voltage drop compared to the 12 volt verison but still have some issue but once I know how far the conductor run will be then I can able figure out if your exsting conductor can handle without voltage drop issue.

My SOP is always put about 3 to 5 % voltage drop but I try to keep to 3% much as I can so it will not affect the performace.

Q: how does this splice work? what kind of connectors are used? what kind of a cover plate? and is it code to have this low-voltage splice in a junction box in the wall? or does it have to be in/under the cabinet somewhere?

thanks for any help. i have wired my entire kitchen so far, and am getting hung up on this low voltage stuff!
Some low voltage lumianries will have junction box to use the convetntal wirenuts etc so check with the manufacter to see what type of space of junction box and what they need to meet the requirment so the answer will varies a bit.

I think the LED is a way to go due they save alot of engery and they are dimmable but only one small quirk is glare if you have high gloss countertop unless you have frosted lens that will soften up a bit.

Merci.
Marc
 
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Old 10-24-10, 08:56 AM
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Hi Marc,

regarding voltage drop:

If I have the knockouts for the three runs I mentioned, then the distances from transformer to LEDs would be very approximately:

1) 12 ft
2) 8 ft
and
3) 16 ft

here is a link to a crude schematic of the undercab lighting arrangement:
Picasa Web Albums - sarah - design and fl...

The kitchen wall with the LEDs is about 16 ft long, and I was thinking of putting the transformer (in the basement directly underneath the kitchen) about 6 ft from the end of this wall.

are these runs too long? i am able to put the transformer anywhere, really, but i am avoiding the area under the sink bc of all the plumbing. that is why it is shifted a bit right of center...

regarding junction boxes and splicing:

i was thinking of using the environmental lights high brightness premium, a new brighter version of the environmental lights premium. they dont seem to have any junction box, just the special fitting at the end of the light bar for their low voltage cable.

and finally, about glare:

luckily i dont think we will have any problem with glare, because we are planning a wooden countertop. do LEDs have a bigger glare issue than other undercab lights?

thanks alot for your help. i really dont have any understanding of voltage drop and no experience with low voltage wiring...i started out assuming that i could just run the low voltage cable in my walls, but quickly learned here and on other forums how wrong i was...

- s
 
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Old 08-02-11, 12:12 AM
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LED Undercabinet

I'm getting ready to do the same thing. I'm running 120V AC to a 65watt transformer that puts out 12V DC. From that I will run 4 DC circuits up thru walls (I believe that needs to be 14g Romex -- huge overkill for 1W but behind the wall codes don't take into account the low amperage of DC units). Those will go to regular electrical wall boxes behind the counter with DC dimmers from ****** or just normal on-off switches for some.

The output 12V DC from the dimmers/switches will go in the wall up to the cabinet level (again 14g Romex -- sigh) into a small box where the Romex will tie to the "lamp cord" wire for the dimmers, coming out the wall behind the cabinet at the lower end. My intention is to drill a hole in the cabinet bottom trim, thread the lamp wire thru that, and then clip the lamp wire to the bottom of the cabinet, running it to the front of the cabinet which will have low-profile *****l LED strips****** or . That way there is nothing in the cabinets and nothing on the wall except a normal switch or dimmer. Each item will be individually controlled.

Note that voltage drop is a function of amps and wire size. The overkill of 14g wire for most of the run means with the less than 1amp of DC current that the runs could be 100 feet and still only have a 0.5V voltage drop (0.25 V drop in and 0.25 V drop return). That means the 12V nominal would be 11.5V for a 100' run and I only have about 20' runs, so I'm good with the voltage. You can go online to determine voltage drops for any size wire gauge (so many sites to choose from). There is also the issue of "ampacity" for a given wire gauge, the maximum amps the wire can take before it heats too much, but as long as the voltage drop is less than a few volts, you won't get anywhere near the ampacity limits.

My solution was to have one switch per under cabinet because that is what my wife wanted. I can see having one switch for all under cabinets.
 

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