lightswitch rating?

[johnty]

I have just got a 1000w rated dimmer switch. In the accompanying leaflet, it says that's for incandescent lighting; for halogen lights the rating is

500w. Why such a difference?

[Ian Stirling]

All sorts of lights have a much lower initial resistance, when cold, so draw much more power cold.

[Ellis Greensitt]

Beacause halogen lighting draws as much as twice the rated current on startup from cold.

[johnty]

So it's just the start-up that's the problem? i.e., when halogens are warmed up the switch could handle (quick calculate...) up to 20 gu10s?

[BigWallop]

But 20 X gu10s might have an initial current draw equivalent of 50 X gu10s, until warm.

[Dave Plowman (News)]

It's not the switch that's the problem. It's the dimmer part.