I'm doing the exact same thing. In NC, there is no code for less than 24 volts, so you can do what you want. I'm putting some 12 gauge landscape zip wire in the walls in back of the cabinets. Overkill, but not a lot of money. Putting the transformer on top of the cabinet behind the crown. There is a code for the transformers, which says they have to be class II, which is limited to 60 Watts. You can't use outdoor transformers, etc. In any case, they are noisy. Larger wire, multiple smaller transformers mean less heat, less voltage drop.

Concealed low voltage wiring must be an approved method.
NM, AC, etc.
The low voltage signal wiring class is not used for lighting.

The two larger transformers I bought all come with housings that have nockouts for NM clamps and have space for all the connections to be made inside the enclosure. I found some similar enclosures to put the smaller transformers in online. All will be on the bottem shelf of the cabinet.

The LV wire is what has thrown me for a loop today, I drove all around looking for some NM cable smaller than 14/2. One other post from an electrician suggested using a sheathed speaker wire but the closest thing I found was 16/3 in a rubber sheathing. The store also carried 18 guage signal wire but it seemed two small.

No, just use 14/2. I don't think a wire sold for signaling or audio, or certainly a rubber cord is suitable for concealed wiring for lighting. Remember just because it is low voltage does not mean it is danger proof. For example, a 120 watt set of low voltage lights is actually pulling 10 amps at 12 volts but only 1 amp on the 120 volt side. I have seen many people install 300 watt landscaping systems using the cheapest 16/2 wire they can find and the wire is very hot to touch. The wire is carrying 25 amps in that sitution and actually needs #10 wire. As said, even low voltage in the house has to be regulated when it is actually carrying a good amount of current and needs to be installed with approved froms of electrical wiring. Romex comes in 14 as a minimum because it is the minimum branch circuit circuit cappacity.

Thanks Spencer. I am going to use Romex. The loads are minimal, 3 of the wires will only be connected to 1 20w 12v bulb 1 to two, and the last to 3 20w bulbs.

"The loads are minimal, 3 of the wires will only be connected to 1 20w 12v bulb 1 to two, and the last to 3 20w bulbs."

While the power dissipation may sem minimal, the penalty for low voltage wiring is the curernts that get very large.
Even a single 20 W bulb on 12 V is pulling ~1.7 amps.
Voltage drop in low voltage circuits is also much more apparent.
2 V on a 120 V circuit will not even be noticed (OK unless it is beside another light at lower drop that is runnig hotter.

My pcuk light don't have a transformer, they just plug in like a regular lamp, thus I'm just going to wire them into a lightswitch.

If you have 120 V puck lights, get ready to replace the bulbs very frequently.
A 120 V filaments cannot take even the normal vibration from the cabinet it is mounted on.

spencer or others

did i read this correctlty - that I can use 14/2 wire on the load side of the transformer to supply low voltage lights?

the reason I ask is that I thought my electricians wired my kitchen and butler pantry above cabinet wiring incorrectly - but maybe it is ok.

For the above cabinet lights - they have a switch leg coming out of the wall - not in a box. From that location - they daisy chained the circuit to 3 other locations where sections of cabinets are located. Is it possible to use the 110V switch leg to drive a transformer (located at the top of the cabinet) and then use the other 14/2 wire on the load side of the trasnformer to carry low volatge - 12 or 24 volts? If that is so - that would be wonderful.

They did use low voltage cable for my under cabinet low voltage lights. This cable is black - at least 14 guage 2 conductor stranded wire. They ran 4 of these cable lengths from a central location to where the cabinet sgements will be and they also have another 110V feed at the central location - presumably for another transformer. I thought this is how they should have run the above cabinet lights - but they did not do it the same way. Not sure why.

It makes sense to me that the 14/2 wire could electrically carry a low voltage - just wasn't sure if code allowed it.

Thanks.

Concealed LV wiring (inside walls) must be an approved cable:
NM, AC, MC, etc.
All these cables have insulation rated at 600 V.
You can use them at any lower voltage you want, and you are required to for concealed LV wiring.
The place you get some relief is on UNconcealed wiring under upper cabinets. Since this wiring is NOT concealed and is on the secondary of a transformer (or power supply) you can use less rugged materials.
LV lighting does not usually meet the power limits for signal and control class wiring, so treating it like thermostat wiring is NOT allowed in concealed locations.

brickeyee

the concealed LV wire they ran is approved cable. That is not the issue.

It is the other wire they ran - the 14/2 - for the upper cabinet above cabinet lights. Can I use that wire to carry low voltage instead of 110. I think I can - but would like confirmation.

They also ran 14/2 wire in my butler pantry for below cabinet lighting. I want to make sure I can run LV on that too.

Thanks

Of course you can use it to carry low voltage.
Why would you even thing otherwise?

code is one reason i thought of. we have that cleared up.

the other reason is maintaining the same level of volt/amps to all of the the lights.

my lighting people tell me that using 14/2 to carry LV would be ok for short distances (less than 15 feet or so.) i have about 30 feet of total run. based on that - they suggest stranded wire.

i will review this with the electrician to see what can be done. they did not wire it per the plan. i wanted to see if we could avoid re-work of the wiring which has a riplle effect on other items.

If the largest load is 3 20 watt 12 V pucks are 5 amps in #14 the drop will be ~0.8V (about 7%) for a 30 foot run.
It may not be to high if the lights are not near each other, but check the other runs.
#12 would decrease the drop to ~0.5 V.
"i have about 30 feet of total run. based on that - they suggest stranded wire."

Stranding does not make any difference in voltage drop, just wire size.
You can use the drop calculator below to check everything out. Just remember that the conductor length is 2x the physical distance.
I have not verified this calculator.

Here is a link that might be useful: V-drop calculator

brick

I will actually have 24 x 12 volt (10 watt) lights on the circuit. 12 lights on each side of the butler pantry.

The 12 lights on each side are for in cabinet lights (there will be one per shelf per left and right cabinet - so that takes up 8 lights). The remaining 4 lights are for under the cabinet. This is duplicated on the other side of the BP.

The original plan was to have 1 300 watt transformer drive all of the lights. I have decided now to use 2 120 watt transformers, one for each side of the butler pantry - mounted above.

I no longer need the 14/2 wire that was put in for the below cabinet lights since I can run the LV wire from the inside cabinet lighting through the bottom of the cabinet to provide a supply below.

Thanks for the info. I am sure it will come in handy down the road.

These installations with large capacity transformers almost always turn into a mess.
The wire sizes get very large very quickly and difficult to work with and connect to try and keep voltage drop down and minimize color shifts from uneven voltage.

It is far easier in most cases to use smaller 60 watt power supplies and locate them under the cabinets near the wall adjacent to the lights.
A 60-watt hard-wire electronic transformer measures 7/8inH x 1-3/8inW x 2-5/8inL.
The plug-in units are slightly larger.

If you use 300 W transformers you will be dealing with currents up to 25 amps at the transformer output with it fully loaded.
Now you are up to wires in the #8 and #6 realm. They are both expensive and large, and difficult to work with in cramped spaces.
These are the size of cables used to feed an electric range.

Here is a link that might be useful: Pegausus undercab puck lights

The link has changed in this post:
Posted by brickeyee (My Page) on Fri, Aug 17, 07 at 8:37

These installations with large capacity transformers almost always turn into a mess.
The wire sizes get very large very quickly and difficult to work with and connect to try and keep voltage drop down and minimize color shifts from uneven voltage.
It is far easier in most cases to use smaller 60 watt power supplies and locate them under the cabinets near the wall adjacent to the lights.
A 60-watt hard-wire electronic transformer measures 7/8inH x 1-3/8inW x 2-5/8inL.
The plug-in units are slightly larger.

If you use 300 W transformers you will be dealing with currents up to 25 amps at the transformer output with it fully loaded.
Now you are up to wires in the #8 and #6 realm. They are both expensive and large, and difficult to work with in cramped spaces.
These are the size of cables used to feed an electric range.

Here is a link that might be useful: Pegausus undercab puck lights

Here is a link that might be useful: Pegasus undercab puck lights