I'm currently fitting a fair number of these things. What I discovered when I removed some old fittings (I say old, they can't be more than a year old but the previous owners decided they'd look nice covered in artex) and found where they'd been fitted beneath a boarded loft and covered in insulation, the terminal chamber had melted to the point that the only way to open it was to literally, crack it open. The plastic had become brittle.
So personally, I'm making sure every fitting has reasonable clearance from loft insulation. It might not catch fire itself but a melting light fitting shows a pretty careless installation.
I've also noticed how much the design of these fittings varies. I've bought from all the main DIY places most have the terminal chamber mounted directly above the lamp. However, some I bought recently have the chamber mounted offset on a small arm so it's not directly over the lamp.
Some I've bought (homebase) have a terminal chamber design that is downright dangerous. You undo the lid retaining screws and bare screw connectors fall out, still connected to the cables. Now of course you should disconnect the supply when working on these but they are sold in a DIY shop where anyone can buy and install them.
Which leads of course onto the whole aspect of anyone being able to buy equipment that could come under part P. The best example being in my local B&Q warehouse, a huge wall hung sign proudly showing you 'how to wire up an electric shower'! I wonder how many electric showers they've sold to the general public since part P came into force? And these downlighters sold in B&Q still come in a pack showing you the zones in a bathroom and where you can and can't fit them. How about 'these lights are not suitable for DIY installation in a bathroom'? In fact, if the deputy prime ministers office is so keen to implement part P, why don't they sort out these DIY places by forcing them to use clear and up to date signage?
