Today I replaced a ballast& coil in an outside HPS light. This is a 277V fixture on the same circuit as probably a dozen F40T12 fixtures and half a dozen U-tube 40W fixtures.

When I was done with this single HPS light, I turned the CB back on and the HPS fixture came on, another HPS fixture on the same circuit came on, all the 4' F40T12 fixtures came on, three incandescent exit signs on the circuit came on, and every single one of the U-tube fixtures would NOT come back on.

They glow a dim bluish glow but never got started. I turned the cb off and on a couple of times and got the same result every time.

Both types of fluorescent fixtures have magnetic ballasts, the voltage in this building is low everywhere, around 265V. I checked this circuit when running and got 265V.

What's going on?