It seems that there are a few people unhappy with the EU ban on 100 watt incandescent bulbs..

So Ulf Ziegler has bought up 3000 incandescent bulbs, presumably enough to last him the rest of his life. He obviously has to store this somewhere. Motivated by pure curiosity, I tried to calculate the amount of space he needs, believing at first that he would need to set aside a whole room. But when I crunch the numbers it seems that he needs not even a standard walk-in closet. Or in European style, three or so movable wardrobes (or armoires as I think we call them in Americanese). Though this is a mere arithmetic problem I must have made a mistake somewhere, because my final result doesn’t seem nearly big enough.

Assuming the bulbs came packed two to a box, and using such a box that I have here, I estimate each box to be 2.5x2.5x7 inches. Ulf therefore has 1500 boxes, so I come up with

2.5 x 2.5 x 7 x 1500 = 65625 cu. in.

Divide by 12**3 to get cubic feet, 37.97743.

Assume closet vertical space to be 8ft, then floor area is 4.75ft–not even 2x3 feet!

Surely you need more space than that to store 3000 light bulbs. Where did I go wrong?

i have a 10 pack, 12in x 4in x 4.5in, about 0.11 cu.ft.

similar results as yours

Yikes, your Imperial lightbulbs must be enormous. 38 cubic feet is enough to hold 280 US gallons, according to the conversion table I found, so that seems quite a bit larger than our metric European bulbs. I just measured a generic 2-pack of 60W incandescent bulbs I have at home and found that it’s almost exactly 360 cubic centimetres (9cm*8.5cm*4.7cm, to be specific.), so that means we’ll be able to pack almost 3 of those for each cubic decimeter of volume and 1,500 of them will take up 540 cubic decimeters, which is just about 19 cubic feet. So I think he can probably get away with stashing them in a regular closet as long as he doesn’t need to store anything else in there.

I often find volumes surprising. Third powers grow quickly.

You could stack 1500 boxes in a 10x10x15 array. Not all that big, really.

Of course if you increased the length, width, and height by a factor of ten each, you could store three *million* light bulbs.

Now that I think about it, there used to be a great math section at the old California Museum of Science and Industry. I think it was rather famous, actually. And in it there was an exhibit demonstrating exactly that which used, oddly enough, a cubic array of light bulbs. There was a button for each dimension, and if you pressed them all you would be looking at 1000 bulbs. But the whole thing wasn’t much bigger than a large washing machine.

My stepdaughter is teaching arithmetic in a private school over there, I emailed this problem to her thinking it might be interesting for her kids.

One thing I’m sure of is that Ulfi is not a member of the Green Party :}