Hello!

I have 2 long rows with multiple F96T12 (2 bulb) fixtures each. Each row is on it's own switch. Both rows began blinking off in cycles every 20-30 seconds. All in unison. Basically, it looks like it does if the main power blinks out for a a half second. I'm assuming the two rows are sharing a neutral for this to happen.

One fixture seems to be affected more than the others, and more so on one bulb. I pulled both bulbs and the others kept doing it. If I turn that row (row 1) off at the switch, the other row (row 2) quits blinking and work as they should. If I do the opposite and turn off row 2, row 1 still continues to blink. One bulb in another fixture that has a bad ballast also has a dim surge to it when the others blink. Pulling those 2 bulbs did nothing to help there either. As far as where to start, I'm assuming on row 1, but.....

Does this sound like a ballast somewhere in the chain creating oscillations or a cyclical surge?
Or more like a wiring issue?
Or what?

 

Even though each row is on separate switches, are they all fed off the same circuit? If you connect a meter to the circuit can you see the voltage vary?

I would suspect either something is up with the circuit breaker or the connection to the panel. Or there could be some other piece of equipment on that phase/leg that is causing a dip in the voltage.

 

Putting a meter on it is what I was going to do in the morning. I'm assuming they are on the same circuit, yes. I'll have to see what else is on it, as well.

 

No variants or voltage dips at the box. There were dips at the fixtures. I removed the power a few fixtures down to the right from the feed and it stopped. I was able to narrow it down to one fixture fairly quick. With only it removed from the chain, the voltage dips and blinking stopped everywhere else. I'll rewire it and a new ballast one of the coming mornings when it's cooler and hopefully it's good to go.

 

Nice job tracking down the issue.

With old-school T12 fixtures, you may want to consider changing the fixture to direct wire LEDs instead of replacing the ballast.

 

Yeah. I had been slowly replacing them, after a ballast failed, with direct wire LEDs with single pins that fit into the existing fa8 tombstone before the corona started and shipping became a process for them. I bought a case of ballasts from a local supply during that time. I have 3 left and will go back to that soon.