Lutsoad wrote on Today, 17:55:
Went dumpster diving but didn't find anything useful so I brought this beat up 3 tube fixture with the old magnetic ballasts home. It's probably from the 80s.
How do I wire this thing? Never dealt with tube fixtures before and don't want to blow things up especially those huge caps.
There are 0 - 1 -2 -3 on the block but I don't want to experiment too much, it seems that all 3 wires (black-white-grey) could be the phase while 0 (blue) is neutral. Maybe the 3 tubes were controlled separately but I'd like input from someone who knows exactly what's up. Thank you.
Funny enough, I was just looking at the light fixtures at my uncle's work shop a few weeks ago and was wondering the same thing as you - how they were wired and why.
You are indeed correct in assuming that each tube has its own phase wiring while neutral is shared.
As for why: these light fixtures were common in industrial buildings with 3-phase power. In Europe, in particular (which is where I am guessing you're located like I am), in order to smooth out the somewhat harsh blinking from the light tubes (from the 50 Hz power line), each magnetic ballast is wires to a different phase. This way, all of the tubes are blinking at 50 Hz, but all 60 degree out-of-phase with each other. So the light coming out the fixture appears much smoother. In large depots and/or industrial places, this also evens out the load across the phases.
From what I can see, indeed it appears that Neutral is for the blue wire, whereas black, gray, and white go to phase. If you don't have 3-phase power, like my uncle's shop, you just wire all of the phases together - i.e. black, gray, and white are phase.
I wouldn't worry about the big caps. Despite being old, most of these are pretty well made and generally don't fail too often... and they are rated for the full line AC voltage, so won't really blow up even if something isn't quite right.
I believe these light fixtures are made for T12 -type tubes. T8 will probably work too, but might wear out prematurely (like they did in my uncle's shop.)
*edit*
Yeah, it says it on each ballast's label: it's capable of either 1x 40 Watt tube or 2x 20W tubes in series. 230V, 50 Hz.
