Ioannis: I am trying to take all of this in but i dont understand all of it.

These LEDs do work fine if i put 4 in series on 12V (3V per LED). Thats the min value specified in the datasheet. They are pleanty bright enough at that.

Sorry but i dont understand what that pic means.

mackrackit: This confuses me a bit. you say theres no need to worry with 5 LEDs on 12V but they could be a bit dim. Are you saying theres no need for any resistor? I wouldnt normally use a resistor in this case anyway.

I may have misunderstood but i think some previous posts said that 80 LEDs (3V each at 240V) would blow up because of the current. If i use a transformer that supplies 12V 6A then isnt this the same problem?