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theatretch85 04-08-2009 12:28 AM

Roughing in Undercabinet Lighting
Part of my rennovation project includes adding a code required GFCI outlet in the kitchen where there should be one (more than 24" between outlet and sink) and installing undercabinet lighting. I think I have decided to go with Low Voltage Xenon lighting and as such it will require a transformer. I am not too concerned right now about the location and mounting of the transformer, but I do want to get the wire run so I can finish off the sheet rock and put up cabinets when the time comes. What kind of wire should I be fishing through the wall for the low voltage lighting? Should this just be "install rated" 2 conductor wire? I believe I might have some 14 guage wire thats twisted pair and rated for in-wall use.

Also, Is it "ok" to make a wire connection behind the cabinet in the wall or under the cabinet and concealed by a false panel to recess the lights into? This would be ideally with out a box but is low voltage (12 volt). I understand Low voltage is dealt with differently and hoping that this undercabinet lighting can be done relatively easily.

Some options I have thought about for the location of the transformer are under the sink, behind the dishwasher (or fridge), in the cabinet above the microwave/range hood, or in the open ceiling in the laundry/utility room downstairs (this room's ceiling will not be finished off).

Bob Mariani 04-08-2009 05:27 AM

I would run a 14/2 from the switch used to control the lights to each transformer. Above the microwave and in the sink cabinet are both good locations for the transformers. First you need to determine how many lights on each transformer and how many transformers you will need. This is all you need before drywall. Wire gauge smaller than 14/2 should not be concealed. From the transformer to each light run the light under the upper cabinets to feed the lights (exposed)

InPhase277 04-08-2009 06:56 AM

You need to size whatever wire you need to the load. Low voltage lights can pull quite a few amps, and it is amps that heat wires, not volts. A 50 W lamp at 12 V will pull about 4.2 A. Some 16-2 or 14-2 in-wall rated stranded speaker cable would be ideal in this application. If I installed this for a customer, I'd use small wire nuts, orange or blue usually (making sure they had metal springs inside).

theatretch85 04-08-2009 07:18 AM

Yeah I was possibly considering in-wall rated heavy speaker wire. At most each run of wire would have 3 lights on it; figuring 20 watts per bulb (I think its 10) that's 60 watts and at 12 volts that works out to 5 amps on that particular wire.

I am actually looking to special order the transformer to get a hard-wired version that will power all of the lights (150-300 watts). It's my understanding that code does not allow a dimmer controlled receptacle so a plug-in transformer would be out of the question to be dimmed (which I want the ability to dim these lights). The only thing the hardware store near me sells is the plug-in transformers and I had thought originally about line voltage so there would be no transformer to worry about, but then that gets to be trickier with wiring those lights through the wall.

PS. Inphase, I totally agree with using the wire nuts with the small metal spring inside to ensure a solid connection with the wire.

Bob Mariani 04-08-2009 07:23 AM

Just use the hard wired transformer and connect in a junction box and not an outlet box.

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