Headlamp power, well I never knew that!

[HDI]

Had occasion to replace a dip beam headlamp bulb on the Xantia last week, so I pulled one from a donor headlamp already removed from the car. I pulled the bulb from the dip beam unit first but strangely it popped as soon as it was turned on! No problem thought I, I'll pull the bulb from the main beam unit. When I examined I found the power was 100 watt! I checked the original blown dip, and the blown replacement dip and they were both 55 watt. So, I thought 55 watts was the maximum legal power for headlamps in the UK, so why were the main beams on this donor unit 100 watt? Were they fitted by a previous owner? So I pulled the bulbs from the other headlamp still on the car, and they were 55 watt dip, 100 main. So are the bulbs on my Xantia in use!
Anyway, I replaced the blown dip again and it worked ok.
I've just checked UK headlamp regs and there is no upper limit for headlamp power or intensity! I'm really surprised, I've always believed the upper limit was 55 watt!

[demag]

I always thought it was 55w but noticed modern bulbs are usually 60w main.

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[Paul-R]

AFAIK 60w is the limit for 12v bulbs and 100w are illegal for road use. They're great for use in the forests when rallying though and do light up the open road (on private ground of course).

[HDI]

Thats what I thought but there is no specified upper limit, you can fit what you like! That is from an officail website.

[HDI]

This is copied directly from the 1989 Vehicle lighting legislation,

"8. Wattage–

(a) A motor vehicle with four or more wheels first used on or after 1st April 1986:
No requirement

(b) A three-wheeled motor vehicle, not being a motor bicycle combination, first used on or after 1st April 1986–

(i)having a maximum speed not exceeding 50 mph:
15 watts minimum

(ii)having a maximum speed exceeding 50 mph:
No requirement

(c) A motor vehicle with four or more wheels first used before 1st April 1986:
30 watts minimum

(d) A three-wheeled motor vehicle, not being a motor bicycle combination, first used before 1st April 1986:
24 watts minimum

(e) A solo motor bicycle and a motor bicycle combination–

(i)having an engine not exceeding 250 cc and a maximum speed not exceeding 25 mph:
10 watts minimum

(ii)having an engine not exceeding 250 cc and a maximum speed exceeding 25 mph:
15 watts minimum

(iii)having an engine exceeding 250 cc:
24 watts minimum

9. Intensity:
No requirement"

[ekjdm14]

But the one stipulation (as I understand it) it that the bulbs have to be E-marked, and anything over 55w (single filament) or 55/60 (twin filament) won't have that marking.

Although it's not even something the MoT man can check, it is still a legal requirement for your headlamp bulbs to bear the E-mark and is a potential point of dispute for an insurance claim where visibility/dazzling was a possible factor (you could be refused a claim/be found at fault if your bulbs in any way contributed, or could have done, to an accident).

Our Escort passed it's MoT with 100/80w bulbs which I only discovered months later when one blew, though "technically" in a court of law the car was not roadworthy and never had been since our ownership.

[HDI]

E marking isn't mentioned in the regulations though, so it can't be legally enforced.

[GiveMeABreak]

You are all forgetting that simply replacing a bulb with a higher wattage in your standard headlamps is a sure way to fry them. They are not designed to dissipate that sort of generated heat and will either potentially catch fire or melt your lenses - but hopefully will blow the fuse before that happens. I tried a 100W in one of my old XMs many years ago as the light output was miserable. It just kept blowing - far too much heat generated.

[ekjdm14]

HDi, I wouldn't like to find out the hard way if this is true lol. That said, the 100/80 setup in the escort was noticeably better than standard so might invest in another set next spring when it comes out of hibernation. For use on campsites only, of course.....

[ekjdm14]

You are all forgetting that simply replacing a bulb with a higher wattage in your standard headlamps is a sure way to fry them. They are not designed to dissipate that sort of generated heat and will either potentially catch fire or melt your lenses - but hopefully will blow the fuse before that happens. I tried a 100W in one of my old XMs many years ago as the light output was miserable. It just kept blowing - far too much heat generated.

Fortunately the 'scort has all-glass/metal construction. And more than likely the constant blowing of your "uprated" bulbs was down to the wiring/switchgear not being up to the job on the XM, common issue and people often note that higher wattage actually gives roughly the same or less light than standard. The increased failure rate is not due to excess heat, more lack of heat (I'm not 100% on the physics but I believe the lower than ideal temperature results in particles of semi-vapourised filament material sticking to the "glass" envelope as opposed to being re-incorporated in the filament).

The work-round here is to have the headlamps operated by shorter lengths of decent gauge wire & switched through relays. Although as you say, plastic lamp assemblies are prone to being damaged by incorrectly specced bulbs anyhow.

[GiveMeABreak]

I soon gave up on it and put back the standard 55W bulbs - they didn't have a lot of other lighting options in the early 90s when I had my first XM. Now you can officially get the extra output / brilliance bulbs - but I'm lucky enough to have Bi-directional Xenons on my last 2 C5s fitted with OSRAM 'Nightbreaker Unlimited Xenarc' bulbs. These are like lighthouses by comparison!

[HDI]

You are all forgetting that simply replacing a bulb with a higher wattage in your standard headlamps is a sure way to fry them. They are not designed to dissipate that sort of generated heat and will wither potentially catch fire or melt your lenses - bu hopefully will blow the fuse before that happens. I tried a 100W in one of my old XMs many years ago as the light output was miserable. It just kept blowing - far too much heat generated.

Agreed. I wasn't advocating that anyone should necessarily install higher power lamps, just that they can, as there is no regulation saying they can't.
Obviously, in the case of the Xantia, it can use higher wattage lamps because the main beam is 100 watt as standard. I've always thought Xantia headlamps are good on main beam, now I know why!
From reading some of the other stuff in the regs, I think it might also be an issue to modify vehicle lighting as fitted by any given manufacturer. Although that isn't very clear as it's written in jargon!

[ekjdm14]

Although that isn't very clear as it's written in jargon!

As is often the case, when there's a buck or two to be made out of honest Joe Public and his genuine misunderstanding of how things are worded.

[GiveMeABreak]

You are all forgetting that simply replacing a bulb with a higher wattage in your standard headlamps is a sure way to fry them. They are not designed to dissipate that sort of generated heat and will wither potentially catch fire or melt your lenses - bu hopefully will blow the fuse before that happens. I tried a 100W in one of my old XMs many years ago as the light output was miserable. It just kept blowing - far too much heat generated.

Agreed. I wasn't advocating that anyone should necessarily install higher power lamps, just that they can, as there is no regulation saying they can't.
Obviously, in the case of the Xantia, it can use higher wattage lamps because the main beam is 100 watt as standard. I've always thought Xantia headlamps are good on main beam, now I know why!
From reading some of the other stuff in the regs, I think it might also be an issue to modify vehicle lighting as fitted by any given manufacturer. Although that isn't very clear as it's written in jargon!

I don't know what Xantia you are referring to - all the series 2 have standard 55W bulbs - according to the Service docs, including my old SX.

[GiveMeABreak]

Just checked the series 1 too and they also are shown with 55W bulbs as standard - so I think the one you are referring to has had a 100W bulb replaced by the owner at some point.