I would like to connect a halogen up lighter with a dimmer control to a
lighting circuit. However, the up lighter has a 500W bulb (yes I know
this is expensive to run!) and I am concerned about the load on the
lighting circuit.

The rating info on the dimmer switch has two sets of figures with one
set, I assume, referring to the min and max wattage of the bulb stated
as 60-500W. The other set refers to 60-300W which I assume refers to
the rating of the dimmer control itself.

If this is right this would explain why the light came with a 5A fused
plug, because if the load of the whole light fitting was based just on
the bulb rating then the max load would be 2.1A (500/240) and surely a
3A fuse would have been sufficient.

However, if the dimmer switch is rated at 300W then the max load of the
light would increase to 800W (3.3A).

The lighting circuit currently has a max load of 400W (1.6A) and
therefore installing the light still leave a total max load of under
5A. As this is protected by a 6A circuit breaker would this be OK.

If this is OK is there any problem with the light not having the
protection of its own separate 5A fuse as I would cut off the plug and
wire is directly into the circuit.

The switch for the light would be a standard wall switch and am I
also correct in thinking that these switches are rated at 5A.

Any comment gratefully received.