Why wouldn't 3,000 lumen halogen lamp be legal?

> So from what I hear, DOT specifications have restrictions on the output
> and allowable power consumption by each lamp type.
>
> If the 3,000 lumen HIDs are given the ok, why wouldn't an adequately
> cooled, 150W incandescent lamp be allowed for headlamp use?

Google found this for me:

What about higher-wattage bulbs for my DOT-spec headlamps?
One word: DON'T!
If your headlamps have plastic lenses and/or plastic reflector housings, you
mustn't use overwattage bulbs, as this can create serious fire hazards and
cause extensive (and expensive) damage to the headlamp assemblies and wiring
in short order.
Even if your headlamps use glass lenses and metal reflector housings, you
still can't safely use these bulbs because the wiring in DOT-spec headlamp
systems is not capable of handling the level of current these bulbs will
draw. If you disregard this and do it anyhow, you create several serious
fire hazards in the engine compartment and, more worrisome, in the passenger
compartment at the headlamp switch. This problem could be circumvented with
the installation of an extra-heavy-duty relay and heavy wiring, but the
wiring is only as robust as its highest-resistance section; the 9004/HB1,
9005/HB3, 9006/HB4, and 9007/HB5 bulbs used in DOT-spec headlamp systems all
have extremely small electrical contacts. Go ahead and have a look; they're
really spindly! These contacts get extremely hot even under normal (45 to 65
watt) loads. They get dangerously hot under higher (80w, 100w, etc.) loads.
When you go much above 65 watts, these contacts become the point of maximum
resistance. Things start melting and burning, and due to the voltage drop
involved with such resistance, you will not achieve any improvement in your
headlamps' ability to light-up the night. No reputable bulb manufacturer
makes these overwattage DOT bulbs for that reason.
The ones you may find are third-rate junk that not only will not last very
long, but also are made in factories with little or no quality control and
do not tend to be made to the extremely precise filament-placement
specifications demanded by today's advanced headlamp designs for proper lamp
performance.
Even if you could find (nonexistent) overwattage bulbs in these formats with
oversized contacts and ceramic bases, make your wiring adequate to handle
the extra load, and be sure your headlamps contain no plastic, you *still*
would be wasting your time and money to use the overwattage bulbs, because
the optics and beam pattern specified in such headlamps by the DOT does not
respond to overwattage bulbs, except to cause massive dazzle to oncoming
traffic and drivers in front of you via the rear view mirrors, and to cause
extreme backglare in fog, rain or snow. Any way you slice it, overwattage
bulbs are a bad deal all around. You'll do well to avoid them.

Steve Mackie wrote:

>>So from what I hear, DOT specifications have restrictions on the output
>>and allowable power consumption by each lamp type.
>>
>>If the 3,000 lumen HIDs are given the ok, why wouldn't an adequately
>>cooled, 150W incandescent lamp be allowed for headlamp use?
>
>
> Google found this for me:
>
> What about higher-wattage bulbs for my DOT-spec headlamps?
> One word: DON'T!
> If your headlamps have plastic lenses and/or plastic reflector housings, you
> mustn't use overwattage bulbs, as this can create serious fire hazards and
> cause extensive (and expensive) damage to the headlamp assemblies and wiring
> in short order.
<snipped>

Hmmm, I sure do detect a familiar writing style. Betcha I know what
website that came from ;-)


But I think his question related not to the practical limits of halogens
(heat, current draw) but why a *hypothetical* halogen source that
wouldn't cook reflectors and emitted the same amount of luminous flux as
a 3000 lumen HID isn't allowed.

And I think the answer is either a) it IS allowed if the capsule
emitting the light can be made to draw less than the required maximum
(HIR bulbs, for example emit more luminous flux per watt consumed than
regular halogens), or b) its just that the regs limiting wattage were
probably written when all lights were similar technologies and watts
corresponded more directly to luminous flux.

Given that in most ways halogen light is better and easier to deal with
than HID (better color rendering, better alignment with the eye's
natural sensitivity, filament shape is more controlled than arc shape so
focusing is more precise, etc.) there's no real engineering reason.

But I defer to Dan Stern for anything beyond speculation.