Shop Fire

[Don Morris]

I had 10 T8 low voltage 4' units installed in my basement shop when I had a whole home renovation 5 years ago. The home was built in the 70's and the ceilings are only 7 1/2' high for "energy conservation purposes". It was recommended that I place clear plastic covers over the bulbs because of the potential of hitting them while swinging pieces of wood and shattering the bulbs. The clear plastic covers would prevent the shattered pieces from coming down on me. I was just using a pocket hole system to join two pieces of wood and smelled some plastic burning. I looked up and saw the end of one of the unit's bulb cover on fire. The flame wasn't high, only a couple inches. I have two fire extinguishers in the shop. But since I was only a couple feet away, in two steps I was there and thought if I couldn't easily blow it out, I could grab one of the extinguishers. Luckily, I blew the flame out with a couple breaths (I know I'll get a few remarks about that). I thought one of the benefits of T8 units is their low heat production, in addition to their immediate on/off and energy savings. This happened at the end junction. Would be interested if some of you electrician types might have comments. Should I remove the clear plastic covers and just be careful about hitting my relatively low lighting units? I'm now very careful about leaving the shop with the lights OFF. LOML's first comment was what if I wan't in the shop, had left the light on, and this happened?

[Harold Burrell]

Oh, man!!! That was a tad spooky, huh?!!!

I try to make it a habit to unplug everything when I leave me shop. Thank you for the insentive to continue that practice.

:eek:

[mike wacker]

Belts and suspenders, the safety stuff we do. The clear pastic covers are mandated for areas where food id prepared. Ask your self this question, "If I broke a lamp while swinging a board in my shop, what wouold be the damage?". If the answer is just vacumn up the pieces of glass. Get rid of the plastic covers.

Or change the fixtures to ones with a lense built in.

[John Keeton]

Don, check this recent thread (http://www.sawmillcreek.org/showthread.php?t=124454&page=2), post #6. Could be a possible cause.

[Dave Sharpe]

I narrowly avoided a shop fire years ago, although purely by luck. Id recently installed skylights in a small garage shop in Sacramento, but hadn't even thought about the effect of direct sunlight on my workbench THROUGH the magnifier light I'd been using. I went out to the shop one day and found a 4" long charred trough in my workbench. It took me a while to figure it out. I hadn't been using any flame or heat in the shop, so I briefly considered whether an intruder had been there who smoked....? Eventually I figured out that the magnifier must have been at just the right height to focus the sunbeams onto the bench, and as the sun moved across the sky the focal point moved also, burning as it went..... I still have that workbench with the scar......

[Darius Ferlas]

You might consider wire cages to protect the tubes from impact. My lights came with them, but I don't think it would be hard to prop up a few using lightweight, say 2x2, chicken wire.

[Josiah Bartlett]

It is very likely that the contacts on those fixtures have gotten loose and oxidized over the years, causing a high resistance spot at the end of the bulbs. Since Power=Resistance * Current ^2, you created a hot spot that caused a fire. It really doesn't take much power in a concentrated spot to cause a fire... soldering irons are typically 10 watts or less. One of the side effects of some of the newer electronic ballasts is that they try to start a bulb even if it is in poor condition or the socket connection is bad. You might want to check your ballast model number (its the black box under the sheet metal cover) to see if there is a recall. Ballasts have been recalled in the past.

It would be a good idea to replace all of your bulb sockets at this point. It is likely that all of them are going bad. Usually you can get just the sockets, although 4' fixtures are pretty cheap.

If you can't replace them all right now, at least take the bulbs in and out a few times to break up some of the oxidation on the end caps and feel them to see if they are warm after they have been running for 15 minutes or so.

[Sam Layton]

Don, there is no way I would have the plastic covers on the blubs...

Sam

[Dan Manning]

Looking closer at pic 1, it looks like it started at the plug-in for the lamp and spread. Glad it wasn't worse, and you were there to stop the damage.

[Peter Aeschliman]

Man, I have the same bulbs with the same kinds of plastic covers. I had the thought just the other day about removing them and using a metal grate cover as mentioned above. Maybe I'll do that.

I actually had the plastic covers save my butt the other day while I was drywalling the ceiling of the shop. I knocked one of the bulbs out of the fixture and it fell to the ground. The bulb shattered, but everything was contained in the plastic tube.

The issue isn't the cleanup, it's about the highly toxic chemicals in fluorescent bulbs (mercury among them). Really nasty stuff that you don't want to breath, get in your eyes, or on your skin...

But again, it's probably worse to have a fire start than get a little chemical exposure.

[Don Morris]

I hadn't thought about the chemical exposure. I knew about the mercury, but the other chemicals in their aren't good either. The unit has already been replaced and the plastic covers are on their way out the door. Our take is the fire potential could be far more catastrophic than the short term exposure to the chemicals. And "she who must be obeyed" is right. I will redouble my efforts to remember to turn the lights off when I leave the shop. My daughter-in-law even suggested a motion sensor to shut off the lights in the shop if there is no motion in there after 10 minutes. With the vivid memories of the flame, I'm considering that option.

[Keith Harrell]

Glad it wasn't worse. I don't have the covers so I can't advise on them. I do have the wire cage covers on mine now as I hit one flipping a board around on the table saw and had glass landing on my saw and saw blade while they were running.
My solution was to install the wire covered lights and then wire them all to one switch at the door so when I leave I turn off two switches. One controls the lights and the other controls the two overhead heaters on the ceiling.
I plan on making sure the light switch is off now after reading your post every time I leave the shop so thanks.

[Mike Cruz]

Thanks John K for forwarding my post. I have to say I use the plastic covers. I have seen bulbs fall from the ceiling and explode. Not a pretty sight! When the fire thing happened to me, it had NOTHING to do with the plastic cover. As a matter of fact, the cover was in perfect tact. It was the plastic terminal that was frying. I certainly recommend them. Of course, wire gates do the job, too. I'm just saying you should use SOMETHING.

[Peter Quinn]

Scary stuff. I have some plastic covers on some of my lights. I too have low ceilings in my basement shop. I think if a socket goes bad and starts to smolder the covers may provide a bit of ready fuel to make things go bad but I don't find the covers themselves trap enough heat to cause a problem. I think I'm going to buy a few more fire extinguishers this weekend.

I have slowly been upgrading the fixtures with grated fixtures as the cheep open ones I bought to get going burn out. With those I don't use the covers.