I built a light fixture out of a water pipe and some "vintage" fillament bulbs. I have a micro switch that is operated by a plumbing valve. Everything works, however, when I put 4 bulbs, 40w each, one randomly burns out after 20 sec. I checked the connections, they seem OK, the switch is rated at 240v( im in europe) and 16A. With 3 bulbs the fixtures works. What could be the issue?
I notice that the failing bulb is next to your switch... so i'm suspecting damage from shaking the bulbs while turning them on and off. Which is a pity since I like the switch design... maybe you could redesign it as a wall-mounted switch?
(I have an old gas key which I'm planning to adapt as the knob of a dimmer switch.)