My lizards viv smells funny! HELP?

I've got a new viv for my lizard, it's 4 foot and I've had it for about 4-7 weeks now but we've notice its smelling funny (Not lizard poop smell) but an odd smell and the roof is really hot. We have a new light fitting, it's not plastic or anything but it's white and hard, my brother got me it as he said it's better but I think it's getting too hot near the wires and its the wires I can smell, I don't know what to do as I have no idea about fittings and my lizard needs heat. I keep telling my brother about it and he says its fine but my Viv's have never smelt this way before (I've had a 2 foot, 3 foot and this is a 4 foot) please help