Workshop roof lamp with standing bulbs

Some of my woodwork: Previous – OverviewNext
Published 24May2015, updated 25May2015 and 23Sep2022

This note is in group Hobby and it’s about a workshop roof lamp with standing light bulbs. (Update 23Sep2022: This works with present-day LED lamps as well, if they have E27 sockets. The main idea that’s left was to protect the lamps, which still holds). This way I hope that the electronics in the lamp will be heated less and so last longer (or as long as they say..). It’s for myself, in more need of light now than when I was half my age. Then I used a 300 Watt incandescent light bulb. A replacement some years ago was 200 Watt. It broke the other day, and now there’s no such replacement (that I would even want to have). So I use two 23 Watt fluorescent bulbs now. I call it “workshop roof lamp” because I don’t figure this is what I’d have in my living or sleeping room.

Disclaimer. Electrical hazard etc. Don’t do it if you don’t know how to. Don’t blame me etc.

Workshop roof lamp with standing bulbs (fig1)

Incandescent bulbs lived by being hot. So hot that the metal filament glowed. The normal temperature of the filament was several thousand degrees Centigrade. A 200 Watt lamp heated the room with almost the same wattage. The fixture and the cables had to withstand for as long as possible. That’s why they made ceramic lamp holders. (All in past tense)

Aside: My ceramic lamp socket we found in a dereclict house here in Trondheim around 1974. My guess is it’s from the thirties. They should tear down a row of small wooden houses in Innherredsveien and Strandveien. One of them had been an electrical installation company. This was the day before the machines came. The people had walked out the door. So we didn’t think we nicked the stuff. The day after (or the day after that) the buildings and their contents were in a landfill. I still have several of the ceramic electrical haberdashery saved from the house, and thought it would be nice to reuse another one of them now. (Aside 2: Now there is the nice Strandveiparken park at the site, on top of the Strindheimtunnelen double tunell with four lanes altogether. When they built the tunnel 2010-2014 partly through quick clay they lifted, moved, stored and moved back and then restored the block of houses – including the five listed houses they had stored away for a couple of years. Had the houses they tore down in 1974 been there still, I am sure they would also have become listed. I am glad I’ve stayed long enough to see that)

When we bult the house in 1979 I used one of the ceramic lamp holders for the main light in my workshop. It was of course screwed in the roof facing downwards, to protect the roof from taking fire. But now I had to rethink and turn everything upside down (or upside up?)

Workshop roof lamp with standing bulbs (fig2)

Modern lightning live by heating as little as possible. However, flourescent (or neon) glass tubes, or a single or a group of LEDS, when put inside an E27 lamp will produce some heat. This is OK for the glass tubes, but not for the LED. The Watt per square millimeter of a LED is ok if it’s fastened to an iron bridge, where all of the 3 Watt’s temperature rise flows away with the wind. Inside a bulb it’s worse. LEDs could become 120 deg C which is not really ok (yet?). Then comes the electronics with chips and some capacitors. Even electrolytic or tantalum. The more they can be cooled, the better. Or better: the less they may be heated, the better.

So I thought I should let the heat from the lamp as little as possible hit the base of the lamp, where the electronics are. Therefore the lamps stand vertically. My flourescent lamp’s 23 Watt (@1400 lumen) should go straight to the roof. 23 Watt, or the double won’t cause the roof to catch fire. I also painted a section above the lamp white.

Then I made a transparent box from some acrylic plastic that was in a barber’s shelf that a neighbour had left in front of her garage, to be thrown away from the shop and from the garage. I have even used it outside for a table and it has survivied like five winters now. It was to be functional, so I just screwed the sides and bottom to a square iron profile that I had found in the metal return container at work. Now the two flourescent bulbs have their light source at about the same distance from the roof as previously.  The lamps may of course be replaced with LED bulbs – but not incandescent bulbs, with which the wood might become pyrophoric and take fire long before one would expect. And the acryl wouldn’t appreciate that either. I will make a sign about that. The 200 Watt incandescent was about 2100 lumen I found out, so I replaced it with two times 1400 lumen of the flourescent lamps. So I have 2800 lumen now, but the output diminishes slowly over time, which I have to notice.

Observe, I am talking about my main lamp. I have several others (5) in the workshop. Basically so many that there are no shadows at any of my working positions. One of them is a fluorescent tube. It’s 18 W, 60 cm and gives 1350 lumen. A 28 W, 115 cm fluorescent tube would have given 2600 lm, about the same as my two new lamps.

The colour temperature of my new lamps is supposedly 2500 K (warm), somewhat warmer than the quite white incandescent lamp. If I think it’s too warm I will see if I can find a LED E27 lamp that’s got that much lumen, and replace one of the fluorescent bulbs. I can see that when I take pictures I now need to push the saturation more down.

The light disperser is some foil paper that we used to use at work. I still have a small roll. I just taped it onto the acryclic box.

I now have a much better lamp that I used to have. I can’t wait to go down in my shop after dinner. (Back again: after hours on I held my hands around the bases of the bulbs. They were a little hotter than my hand. May they last long!-)

See Strandveiparken, Strindheimtunnelen

Norwegian search words: taklampe med stående lyspærer til bruk i snekkerrom eller arbeidsrom. Keramiske sokler. Akrylplast. Gjennomsiktig kasse. Diffusjon av lyset med hvitt foliepaper.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.