UL requirements for outdoor yard light

[oldestguy]

Hi: My yard light is a Metal Halide type made by Cooper (but from China). It has a plastic truncated cone lense under an aluminum "bonnet" that make up the main enclosure for the bulb.. The instructions call for placing a plastic disc type lense at the bottom of this enclosure.

This light fixture is roughly identical to one that was there before, by Cooper also, but a mercury vapor light bulb. That older mercury vapor fixture had no bottom disc lense as this current one has, but otherwise was practically identical to the the current fixture.

When I asked Cooper was this bottom plastic disc part needed (due to this fixture becoming filled up at the bottom of the enclosure with bugs), they say it is needed to keep the UL rating.

The did not say it was needed for any reason other than that UL rating.

The only reason I can think of for needing that bottom enclosure is for stormy weather to keep moisture droplets from hitting the bulb itself, which sits well up in the enclosure. The older mercury vapor fixture never was bothered by storms for the 10 years it was used.

This light is only 70 watt rating and the older mercury vapor bulb was 175 watts.

Any thoughts?

 

[itsmoked]

UL is mainly interesting in preventing fire and at a far lower interest level, of preventing electrocution.

Perhaps if the unit gets rain blown up in it, or birds nest in it, this could result in a fire?

I would think that the bottom cover would reduce or eliminate the bug issue.

It could also be needed to get the most out of those 70W.

Personally I'd use it until something else demonstrates not having would be better.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

UL's rules are, once you submit a product design that contains a set of components, EVERY one of those components must be preset to maintain the UL listing. The alternative would have been for Cooper to submit the same fixture twice, once with and once without the cover. At roughly $20,000 per evaluation, you can see why they would not have bothered.

But do not take that as an endorsement to go ahead and ASS-U-Me you can do without. Keith's points are still very valid.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[davidbeach]

Metal Halide lamps have a history of what is known as "non-passive failure" that does not affect Mercury Vapor or any of the Sodium lamps. Many MH lamps can not be used in luminaires with open bottoms so that the extremely hot products of the failed lamp do not cause a fire.

 

[itsmoked]

Ah yes! That is very true too. If the lamp explodes hot glass can go everywhere.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[EEJaime]

Davidbeach is correct. These low wattage MH lamps have a history of end of life failures that cause the lamp to shatter and drop hot glass. It is a safety and liability issue. There were a few instances of fires and minor injuries. So there became a series of lamps that are to be used and UL listed for use in "enclosed fixtures only". If this is a yard light, and it is over an area that is not trafficked by your family, and there is nothing under it that will catch fire, then you can use the fixture, you are just doing so "at risk", which is the same thing people do when they plug in multiple extension cords, replace GFCI outlets with non-GFCI outlets, don't close the matchbook cover before striking, sip dark black liquid out of a coffee cup that "MAY BE HOT!", etc....