Had you considered buying a length of Aluminium LED carrier strip with clip in diffuser, plus a length of LED strip light and a single mini driver for the lot. There are lots to chose from, both the carriers and the LED strip. here are a couple of suppliers:-

https://marcled.com/24-led-aluminium-profiles

https://mkshop.co.uk/led-strip-lights/aluminium-led-profile/

I'm guessing the lights will be behind the front cabinet down-stand.
To provide a single connecting cable run you'd drill up into the cabinet and through the cabinet sides with something like a 5/6mm drill bit. The LED strip supplier will be able to provide pre made LED strip snap-connectors with a cable tail attached. All you'd have to do is crimp the tails together from one to the next inside the cabinet and then hide the cable in micro self adhesive trunking. The smallest trunking I've seen is 9mm x 5mm. Any reputable supplier will advise on the driver required for your particular strip length and type.

Thanks. Yes, the current lighting is behind the cabinet downstands and the connecting wiring is routed into a slot cut in the cabinet sides and covered by the dressing panel.

Probably not able to use the existing wiring as it has little plugs at each end that fit the existing lights and will certainly not fit anything else (that would be too simple; let's redesign so the consumer has to buy everything again!) But a reasonably easy fix.

Given that the total LED length would be only 3m, would one driver at the start supply the required power so that the last LED strip would be the same brightness or would I have to arrange something else with extra wiring?

Posted By: RexProbably not able to use the existing wiring as it has little plugs at each end that fit the existing lights and will certainly not fit anything else (that would be too simple; let's redesign so the consumer has to buy everything again!) But a reasonably easy fix.

Cutting the connectors off counts as 'reconfiguring' in my book :) You might be able to buy the connectors though. Most of them are standards of one sort or another; the difficulty is just recognizing the right one.

Just looking at TLC LED tape and the is this in the Q&A:
Q) Can I connect the tape together to form a loop?
A) Yes you can. This will even the brightness out on the LEDS across the 5m length

Do I therefore assume that a cable from the end of the run, returned to (where?) will ensure that everything is at full and even brightness?

My other question, apart from install and see, how would I know if the brightness is sufficient or maybe, too great?

Posted By: RexTLC LED tape

Not sure which product you're looking at but the pages I just looked at don't include basic specs such as colour temperature or CRI so I'd be very cautious about buying them. Let alone lumens versus wattage! (edit to say - the last is the information you need to know how bright they are).

If they can be connected in a loop then it means they're voltage driven and all the LEDs are wired in parallel. Just like a ring main. Since LEDs are current-operated I don't know how such circuits work. Does anybody know? Do they have resistors in series with each LED? That sounds very inefficient.

DJH - ours seems to have groups of 3 SMD LEDs in series with a 150ohm SMD resistor, that group is repeated down the tape, all the groups are in parallel with each other between the +12V and - conductors which run down each edge of the tape.

If we guess 2.5V forward voltage across each LED and 1V voltage drop in the conductors, that leaves (12 - 3*2.5 -1) = 3.5V across each resistor, so it will set the current to 3.5/150= 23mA which seems about right. So 3.5/12 = 30% of the power is wasted in the resistors.

https://www.instyleled.co.uk/support/what-are-the-differences-between-types-of-led-chip/ suggests their basic led stickytape is 5W and 350 lumens per m, so that's 70 lumens per W. Not record-breaking, but the efficiency comes in from it just illuminating the worktop , rather than the whole room.

Posted By: WillInAberdeenDJH - ours seems to have groups of 3 SMD LEDs in series with a 150ohm SMD resistor, that group is repeated down the tape, all the groups are in parallel with each other between the +12V and - conductors which run down each edge of the tape.

If we guess 2.5V forward voltage across each LED and 1V voltage drop in the conductors, that leaves (12 - 3*2.5 -1) = 3.5V across each resistor, so it will set the current to 3.5/150= 23mA which seems about right. So 3.5/12 = 30% of the power is wasted in the resistors.

https://www.instyleled.co.uk/support/what-are-the-differences-between-types-of-led-chip/ suggests their basic led stickytape is 5W and 350 lumens per m, so that's 70 lumens per W. Not record-breaking, but the efficiency comes in from it just illuminating the worktop , rather than the whole room.

Thanks for that info. Wasting 30% of the power seems like quite a lot to me. The difference between 70 lumens/W and the over 100 lumens/W from T5 tubes was one of the things that drove me to fluorescent initially. The fittings for tubes include reflectors. I wonder why they don't make LED tapes with series-connected LEDs, although I suppose you'd need a smarter current driver and some method of connecting to both ends of the tape.

Posted By: owlmanI admit, I've never seen any that need to be wired like a ring main, why you'd need anything like that I don't know.

I don't think you NEED to connect both ends, just that you can, and doing so would help to even out any voltage differences. But I'd think it would be pretty marginal, I agree.

The 683 is at the eye's most sensitive frequency, so I think any white light is bound to be apparently less efficient, but I'm too lazy to work out by how much

I see in the same article that cool white 2835 LEDs have a better efficiency of 108 lumens/W versus the 5050's 75 lumens/W. Daylight will be slightly better, I believe. (edit: apparently not - they use 'cool white' in a different, more logical, way to everybody else. They use it to mean 6500+K whereas everybody else uses it for 4000K and uses 'daylight' for 6500K, whilst Instyle use 'pure white' to mean 4000+K). Very interesting site, BTW, thanks for the link!

Also elsewhere on that site is a drawing showing that daisy-chaining metre lengths of tape can lead to uneven brightness, so they recommend wiring the metre lengths in parallel.

<blockquote><cite>Posted By: Rex</cite>I now thinking, rather than replacing everything, strip the electrics from inside each unit (ballast, etc), apply the LED strip to the reflector and solder a connection from the plug to the LED. Of course, a new LED driver at the mains end, then replace the diffusion cover. Everything stays the same, presumably should have sufficient light and they will all work.

Minimal cost and remedial work. Only downside is the LED will not cover the entire length of each cabinet but that would not be a problem.</blockquote>

That's a pretty good idea - I was having trouble finding decent outdoor lights and got some bargain ES lamps and converted to 24V LED Strip. It doesn't need to look pretty inside as you never see it.

Just to note that I'm really impressed with the quality of Ikeas LED lighting - they're much better than most of the other stuff I've seen that isn't much more expensive.

I've got a few bits of their under cabinet lighting mounted in different places now. It's all sold with their connecters on and they do a load of smart home/wireless switching etc but the lamp units themselves just need 24V so you can snip the connectors off and connect to your own drivers. (one caveat being the last time I looked there was a 'last chance to buy' on some items so they may have done their usual thing of redesigning at lower quality to keep the price the same).

I haven't used them, but these under cabinet panels looked particularly cool - https://www.ikea.com/gb/en/p/irsta-led-worktop-lighting-opal-white-10406943/

Thanks for the comments. Have not actually visited Ikea in some time but will check out the LED lights.

Need to visit as some of our kitchen doors and drawers are looking a little the worse for wear. Would be nice to just do a straight replacement, but easier said than done as the door style and colour we have is no longer 'available.' Or more specifically and just to confuse everyone, it probably is but under a different name.

Difficult to tell from the internet.