Can I add lights to kitchen units after they've been fitted or do they have to be done at the time of fitting?

Answer 1

No you can add them at any time, but it would have been easier before the units were fitted.

Answer 2

Of course - you can add them at any time. If you find it hard to get small strip light fittings from local electrical shops because of the daft new regulations about NOT doing it yourself (thank you to all the do-gooders once more....), try a pet shop! They sell them for overhead lighting in fish tanks.