On 25/01/2012 20:56, dennis@home wrote:


wrote in message
...
On Wed, 25 Jan 2012 09:36:25 +0000, Nightjar
wrote:

On 25/01/2012 06:54, Chris J Dixon wrote:
Dave Liquorice wrote:



I never quite understood why the rules specify maximum wattage
rather than light output. It also seems odd that, when the car
has separate dip and main beam bulbs, they are permitted to be
lit simultaneously. I bet you couldn't have a 50/100 W single
bulb.

You used to be able to buy 55/150W halogen bulbs, although it was not
legal to use them on the road. They were very popular on rally cars,
including some of those taking part in road events.

Many years ago I had some 100/160 and a quick check shows they are
still available. All a brighter lamp on dip does if it is correctly
adjusted is light up the same amount of surface but to a greater
intensity so the eyes don't suffer as much from being plunged into a
black hole. A mod was to wire lamps with a relay so dip was on all
the time and was not extinguished when main was selected.
I tried it expecting the lamps to have very short life due to heat but
they seemed to last a reasonable time.

AOL
You have to be sure you don't have plastic lamp housings or they may melt.

It was also necessary to use the headlamp feed wire to operate a relay,
rather than the lamp directly, or the extra current draw would melt the
insulation.

Colin Bignell