D.I.Y. 900-watt CF Lighting Units

[Bob Hart]

CAUTIONARY NOTE:


Out here in Oz, there are some long plastic planters which are right for about 25 CF lamps in two rows of 8 and one row of 9.

I have outlayed an uncomfortable amount of funds for the pots and the lamps, but am yet to cut the mount panels and wire them.

They will come out to approximately the equivalent of 2800w tungsten each and will draw less power from common domestic household power outlets or small generators, which is how I need them to be.

I now have some misgivings as I have since learned that these things are a mercury hazard if they get broken. An emergency evacuation and decontamination of a film set is not a funny business, especially if a whole bunch get smashed.

You all know what happens to lights on a shoot. If people don't hang a toe in a cable and pull a lamp over at least once on a filmshoot, they are simply not alive.

It might be prudent to re-think this whole CF light thing or design fully sealed enclosures robust enough to contain the dust until they can be opened in a controlled environment for repair.

[Bob Grant]

Not to dismiss the dangers of mercury poisoning however the amount of it in the latest fluro lights is very small. I wonder if the amount though was reduced out of environmental concerns or because of the cost of it. Less mercury in the tube means longer warm up times as well.

All our lighting kit that isn't fluro is HID and so far despite many damaged CFLs and several wrecked light fixtures we've only had one incident where the glass broke. The glass is remarkably strong, the glue holding it into the base isn't. If you design your fixtures so that in a fall the lamp doesn't take a direct hit the risk of breaking the glass is very small.

To keep the "CFLs are bad because they contain mercury" argument in perspective almost all our power down here comes from coal fired power stations and coal contains mercury and uranium. In theory the scrubbers should extract it from the flue before it goes up the stack, even if they do then what happens to it is another question.

[Martin Catt]

No one has ever actually posted just how much mercury is in a "typical" CFL unit. I suspect it's rather miniscule, being in vapor form inside a low-pressure housing. My personal take (for what it's worth) is that you'd have to break open and sniff dozens of CFL's before you might approach having an issue with mercury. They certainly contain less than those eight-foot florescent tubes that were regularly tossed in the dumpsters.

Safe lighting practices should eliminate most hazards. I tend to handle my CFL lights with the same care I did for hot tungsten lamps, making sure they were placed in stable positions, properly secured, and all cords taped down or tucked away where people were less likely to snag one.

The biggest worry I have is that some well-intentioned idiot will replace the CFL units with regular filament lamps and have a melt-down and fire because the fixtures aren't designed to take that much heat. As long as the original builders keep control of the lights they've built, there shouldn't be a problem. I tend to overbuild, using mostly all metal parts, so even if I shoved 150 watt filament bulbs in the units, they'd work just fine (and eliminate the need for central heating in winter).

Regards;
Martin

[Richard Andrewski]

Actually there is information on the amount of mercury in these bulbs. Here's an excerpt of an Article titled "Fluorescent Lamps and the Environment":

"Based on a 1999 NEMA survey, the average four-foot
fluorescent lamp contains about 11.6 milligrams (mg) of
mercury. This number has been steadily declining as lamp
manufacturers work to reduce mercury content to the
minimum amount technically feasible without reducing
lamp life. The average four-foot lamp today contains over
75% less mercury than the same lamp would have
contained in 1985."

And thats what was in a 4 foot tube in 1999. A small CFL will have quite a bit less and in general they are using less all the time.

The entire article can be found here:

http://www.nema.org/lamprecycle/nemafluorfinal.pdf

The fact is these lamps wouldn't be as efficient or have a long life if they didn't have mercury in them.

People are and have been using fluorescent and HMI/metal halide on film sets for a very long time so I doubt that this is really a concern. Metal halide and fluorescent are also being used widely across the world in office buildings, shopping malls, warehouses and homes. And all those technologies have mercury in them to one degree or another. Yes sometimes the bulbs break or explode. That is the exception and not the rule though. They are providing benefits in the use of energy and not generating the heat that needs to be displaced by air conditioning too so we can probably take a few calculated risks to get those benefits. LEDs are no where near the cost to output ratio they need to be to replace HMI or fluorescent so until that happens we will continue seeing fluorescent and metal halide in wide use.

You should always be setting your lights up, no matter what kind of bulb is in them so they won't be falling over and if they do to minimize the possibility of any breakage.

[Jonathan Levin]

Martin,

Fantastic light project!!! I want to build something myself. I went to home depot to buy aN N-vision daylight bulb to experiment with my Nikon D2x. (Don't have video camera yet to test with)

Thanks so much for this.

Jonathan