Foil covered disk in ceiling lamp.

February 25, 2007 4:20 PM

One of the lightbulbs in my (apartment's) ceiling light blew out. I removed the glass dome, and found a precariously placed aluminum foil covered disk. Where is is supposed to go? What is it?

The light goes, from top to bottom: (ceiling), plastic base, foil covered disk, lightbulb/socket assembly (protruding through cutouts in the disk). The foil covered disk is not flush with the plastic base that the sockets and their associated wiring jut out of. Rather, it's suspended about a centimeter or 2 below the plastic base due to the support of the head of a screw that's not all the way in the plastic base. The foil covered disk is pretty loose -- the hole in it that the screw goes through is pretty big -- so it is kind of wobbly, and half makes contact with the bulbs/socket assembly. It's also got a couple random pieces of brown tape on it.

My first thought was to get the disk to be flush with the plastic base -- either by tightening the screw, or with tape. I decided not to mess with the screw, and that tape would be best, but then started to think that perhaps the disk isn't supposed to be flush with the plastic base for some reason.

What is this thing, and where is it supposed to hang? Too close to the bulbs/sockets seems like a fire or electricity conduction hazard of some sort, but maybe its not supposed to be too close to the plastic base either. What to do?

posted by sentient to Home & Garden (6 answers total)

Best answer: It is supposed to be flush with the plastic base. The disc is reflective so that the light (and heat) of the bulb is reflected down into your apartment rather than absorbed into the base. As you've seen, these are nearly always cheap cardboard discs with a reflective coating that don't tend to age very well. The best thing would probably be to glue it on, to avoid leaving potentially flammable tape inside the fixture. Otherwise, a bit of electrical tape would be fine. I'd avoid masking tape.
posted by ssg at 4:30 PM on February 25, 2007

Could be a radiant heat shield, to stop your bulb from toasting the plastic base of your fitting. Post a photo?
posted by flabdablet at 4:47 PM on February 25, 2007

Response by poster: Electrical tape it is... thanks!

re: posting a photo - not so feasible, but definitely a good idea. :)
posted by sentient at 5:14 PM on February 25, 2007

I'd expect the adhesive in electrical tape to degrade rapidly in a hot environment like a light fitting. The random pieces of brown tape you've seen were probably double-sided at some stage. You'd be better off with a little contact adhesive.
posted by flabdablet at 5:19 PM on February 25, 2007

Best answer: Electrical tape will be useless, it'll turn to goo in short order. Get some self adhesive aluminium metal tape. It's heat resistant and reflective. You can get it at home improvement borg in the heating section as it's used for wrapping joints in HVAC systems.
posted by Mitheral at 6:02 PM on February 25, 2007

My mistake, electrical tape is probably not a long term solution. If you must tape, do use something that won't catch fire as suggested, but glue is still the best bet.
posted by ssg at 10:35 PM on February 25, 2007