Proper UV for my iguana

[Curmudgeon]

I need some advice.
I have two 40Watt 1.2m exo-terra 5.0 UV lamps set up on the ceiling of my Iguana enclosure. The globes are around 60 to 70 centimetres away from my Iguana. Is this too far away for good UV ray absorbsion? If I set it to the recomended height of 30 centimetres the iguand knocks them down.
Where Can I buy Mega-Ray mvb's?