I had been reading about using the shop lights to start seeds. I went to lowes and found a 2-lamp 4 foot shop light. The specs are; LUZ Industrial, 9240 , Cooper Lighting, Metalux. I think they are on sale for $9.95. I took it apart after reading all the info Zink and others had posted about over driving them. This light has a "Leets Lighting" ballast, md # N-240-2-TP-SH. It is wired different than the pics and diagrams I saw that Zink had done. It has on one bulb , left end a blue wire and a nuetral wire and on the right end a blue and a yellow wire.On the other bulb it has on the left end a red wire and a nuetral wire and on the right end a red and a yellow wire. When I say nuetral , I mean the AC nuetral line coming in on the power cord.It only goes to the light socket and NOT into the ballast.The AC hot ( black) wire goes into the ballast. I ended up taking the wire from one bulb ( blue ), and connecting them to the place with the reds on the other bulb, and connected the yellow to the yellow. It was somewhat brighter, but the bulb temperature was twice as hot ( to the touch ). I should add at this point that the bulbs were GE F40T12 residential light 40 watts, 3150 lumens, 4100K color temp. 72 cri.

The only trouble I had was trying to mount the 2 ballast. The fixture is so narrow it does not allow a side-by-side mounting as the bulbs will hit it, but a end-to-end mounting instead. ( I found out the hard way!, trial and error)