I have a room measuring 10 x 17.5 foot and would like to put some 9 watt warm white LED downlights in they have a 60 degree beam as well. Just need to know how many I should have installed. The room is a living room from an open plan living/dining room.

And don't make the mistake of putting them in symmetrically. Far better to group them where the areas of activity are.  They look better as well.


And get a spare (or two depending on how many you get) because if/when one of them fails then trying to get a matching one a few years downline will be nigh impossible.

I think 9W LEDs would be quite bright so can they be dimmed?

I'm using an array of 4-5W LEDs in my kitchen and it's plenty bright enough. Each of mine produces around 400-450 lumens and are on a pitch of about 900mm.