Saturday, April 29, 2017

LED Fluorescent Replacements

This describes how to retrofit LED bulbs in fluorescent fixtures.  The last time I was up in those fixtures, I don't recall seeing a lot of wires.  Is this four wires into the ballast pretty typical?


  1. I recently refitted a four-bulb 48" fluorescent shop light to use LED "bulbs." The instructions that came with the bulbs were fine, and we just removed two of the wires on each - per instructions.

    It works fine.

  2. i feel like the last fixture i replaced the ballast in had even more wires than that.

    probably a result of standing on a ladder staring at the ceiling making everything seem worse than it really is.

  3. Yes, 4 wires out of each end is typical.

  4. Fluorescents are powered from each end (current flows the length of the tube) so there are four wires from the ballast to the two tubes. The LEDs are powered at one end so both wires go to one 'tombstone'. Because you're just providing power the wires from both tubes go together so you wind up with just your two power wires going to the pair of wires for each tube. The key thing is (unless you're using the special LEDs that are direct replacements and use the ballast) that you MUST replace the tombstone - that's the bit that the tube hooks into. For Fluorescent the two sides are tied together in a direct short - again, the power flows from end to end. For LED you get non-bridged tombstones and each side has one of the power lines. I've replaced all four fixtures in our kitchen and the first one is easy. The rest are a piece of cake.

  5. A convenience store near me recently changed hands, and the new owners did a lot of renovation. One of the things was to replace all the overhead fluorescent tubes with LED strips.

    The store is MUCH brighter now--admittedly it was a little dim before--so if you think that might be a problem, you might want to do your replacement in stages.

  6. If you watch the big box hardware stores they usually have complete lights, that when they are on sale it is less expensive to buy new than to swap out the bulbs in your fixtures.

    At times you do have to wait a month or two for the replacements to go on sale though.