Tim Mitchell wrote:


The dimmer will probably cook. (I'm not sure why they are derated for
mains halogens).


Halogens run hotter, so when cold draw more current than a conventional
bulb.

Dimming means cold filaments and high peak currents, which heats up
dimmers more than running full crack.



Go to an electrical wholesaler like City Electrical Factors or someone,
and tell them what you want to do, they will have something more
suitable than B&Q.