Alexander Galkin wrote:

I am going to build kitchen cabinets and plan to install undercabinet and
inside cabinet lighting. Can someone advise me about the options? What's
advantage of using low voltage over 120V lighting? If low voltage is a
choice when a transformer is placed? Is transformer quite enough? What type
of bulbs are the best? What's the usual spacing between bulbs? And finally
where can I buy good quality undercabinet lighting hardware?

I installed thin fluorescent fixtures up under the cabinets. I leave
one 13 watt unit on 24 hours a day. It works well IF you can find a
pinkish bulb rather than the standard blue "cool white" bulb. The
latter makes meat look black. (I won't go into what GF says about zits
in cool white!)

Perhaps you should visit a number of furniture stores to see how they
light up cabinets.