Well, since this is apparently a low voltage installation, junction boxes are not required - but aesthetically make the installation look much more professional and just overall nicer looking (if you are looking up underneath somebody's cabinet).

Unless local code has some sort of unusual stipulation, you could have just run 14 gauge CL2 in-wall wiring and stapled it up, which is very easy to work with rather than 14/2 NM Romex - especially if this is with low current LED lighting.

I would just look around for some type of enclosure to hide the 14/2 NM to LED wiring connections, but if you can't find anything, it should not be a problem - unless, like I said you have some sort of usual local code that addresses low voltage under cabinet lighting.

Like this Non-metallic Splice Kit 12-14 Awg?

Here is a link that might be useful: CPGI-208169-2

"Like this Non-metallic Splice Kit 12-14 Awg?"

Check the listing very carefully.

Many of those are only allowed in 'mobile' housing.

They are not listed for anything else.

Thought the only gotcha is whether these can be "buried",
if exposed they should be kosher(barring local amendments).

Here is a link that might be useful: http://www.contractortalk.com/f5/amp-no-junction-box-connectors-30448/

The Type NM-1 splicing device is also used with the Type NM-3-Tap device (UL listed E57250). This
combination (NM-1 and NM-3) is suitable for SURFACE MOUNTING without an outlet box in exposed cable wiring
and in EXISTING BUILDINGS/DWELLINGS where the cable is installed in accordance with and as permitted by
Article 336-21 (Nonmetallic Sheathed Cable and Devices of insulating Material- 1999 National Electrical
Code) and the Canadian Electrical Code, Part1, Section 12-522.

Here is a link that might be useful: PDF

'manufactured buildings' only.

Right under "3.2 Applications"

These devices do not appear to be listed for other use4s, exposed or not.

Article 550-10(k) right on the sheet.

They are not listed for other uses.

These devices are NOT acceptable for general use.

Don't see ONLY anywhere in that paragraph "3.2 Applications"

The second paragraph says ALSO USED which I take to allow
other applications as listed.

"Don't see ONLY anywhere in that paragraph "3.2 Applications" "

If hte listing was for other than "manufactured buildings in accordance with 1999 National Electrical Code (NEC) Article 545-13" it would say so.

Listings are always restrictive.

The device may ONLY be used in accordance with the listing, and not in any other way.

The fact it was "listed" under a specific NEC article means it can ONLY be used under that article.

"Mobile homes, manufactured homes, and mobile home parks."
Nothing else.

These are VERY cheaply built items, with a short expected lifetime.

I installed WAC under cabinet linear track lighting.

Here is a link to the junction box:

http://www.waclighting.com/USA/products/?categoryid=18&productid=143

I have five 'groups' of cabinets. Each one has a home run to the transformer. Depending on the length of your run, there could be significant voltage drop.

If you're low voltage at the point of connection, I don't believe that you need to terminate in an approved box.

I'm not an expert, but I don't see why you couldn't use any box you wanted to if you're low voltage. what we did we ran Romex 14/2 from transformer in the basement through the wall, out the sheetrock. We have a bottom on the cabinet that has space, and had the puck lights recessed into the bottom. we wirecapped the Romex to the LV lead on the pucks, and snapped the pucks in teh holes. This leaves it covered, capped, and accessable if need be. Again, this is Low voltage, not line voltage.