Tuesday, December 4, 2018

Replacing Fluorescent Tube Lights with LEDs

File this under "Simple Things That Aren't Simple".

Back in 2014, we added a big room onto our house which has become my playground.  Mostly my playground.  Yes, it shares space with things from the rest of the house, but this is where my metal shop is, where my gun cleaning and reloading benches are and where general wood and other projects get done.  When the addition was done, we had a general contractor oversee everything and the electricians he brought in installed six fluorescent light fixtures.  Mounted to the ceiling, not hanging from chains, the six fixtures are two T8-size bulbs: four feet long and (mumble mumble) lumens of light output.   (T8 is a designation for the size of the bulb, 1" diameter).  I don't recall them ever offering the option of LEDs instead of fluorescents. 

A couple of weeks ago, when I turned on the lights in the shop, one of the fixtures didn't turn on.  Most everyone has seen a fluorescent go bad and are familiar with the flickering and light/dark waves in the tube they get.  That never happened: it was fine then completely dead the next morning.  When that has happened to me in the past it was because the fixture's ballast had failed.  I measure voltage into the ballast, but nothing on its output.  Replacing the bulbs with others I have lying around shows other bulbs won't light, either.

It was time to dive into the world of replacing the fluorescent tubes with longer-lived LED tubes.  It turned out to be quite a morass.  My expectation was that I could buy a replacement, ceiling-mounted light fixture with LED bulbs for perhaps twice the price of a shop light with fluorescent tubes.  The only thing I could find near that price were lights that are metal fixtures with LED strips mounted inside them, making the lights not replaceable.  If you had to change the LEDs, you would need to change the entire fixture. The lights I could find in the home improvement stores were more like four times the cost of the hanging shop light.

These lights are rated for 45 to 50,000 hours of life, and if I'm using them around 10 hours/day, 50,000 hours is over 13 years.  It is reasonable to want to change those bulbs when we have no real idea what technology light fixture might be set to replace it in 13 years?  Maybe its OCD, excuse me: CDO, but I kept going down that path.

I started searching for LEDs, in tubes, that could replace my T8 fluorescent bulbs.  Last April, when I replaced my halogen kitchen lights with LED bulbs, I had done my shopping at a company called 1000Bulbs.  I popped over there and found I could get two bulbs for $3.25 each, but there was a catch.  I needed to buy a pack of 25 to get that price.  There are 16 bulbs in the house.  With a 50,000 hour lifetime, about 13 years, 25 bulbs is a lifetime supply.  Or two lifetimes.  In the box of 25 they were $3.25 a piece.  In single quantities, quite a bit more than that - like $8.  (Not the same exact bulbs as the quantity discount, just what they listed). 

It's a long story, but I eventually found that the most common LED replacements are powered only at one end, one pin for each power lead, and naturally called "single-end" LED bulbs.  That's what these $3.25 bulbs were.  Size wise they go in the same fixture and they have two inert pins on the other end just to support the bulb.  To use those, I'd need to rebuild my fixture - it's not hard, but would be best to take the fixture down and put it on a workbench.  The fixtures have the terminals (colloquially called tombstones) on both ends with the pins tied to each other, called shunt wired, so I'd need to take those out on the end that gets powered and replace them with tombstones that have the two sides wired separately.   This diagram should help:
Shown at the top is the starting condition, the Line (or Hot) and Neutral wires come into the ballast in the fixture.  The ballast has two pairs of wires, two blue and two red, that go to the tombstones on either end.  All of those wires are cut and the ballast removed.  Those shunted tombstones (built into the fixture) are removed and replaced with two new ones that have separate black and white wires.  The wires are connected to each other (black to black, white to white - which are shown gray in my hacked picture, next)  then the Line or Hot (black) wire from the house goes to the black sides of the tombstones and the Neutral (white) goes to the white sides.  The wiring diagram on the bottom of that picture is trying to tell you tie all the blacks together and all the whites together, never connecting black to white.  I can't find anything that definitively said that it mattered to the bulb which pin got black and which got white, but it might be labelled on the bulbs.

Remember that this is 120 Volts AC and 120 kills more people than any other voltage widely distributed.  If this is out of your comfort zone, don't do it.

Somewhere along the line, I found there were double ended LED replacements.  Those would go in the same fixture, but with no need for new tombstones.  In fact, you don't even need to take out the ballast if it's good (yeah you waste 8 or 10 watts in the ballast if you leave it in, so it does impact your electric bill slightly).  Problem was they were out of stock.  Another LED seller I went to was out of them, too.  These would be easier to wire in.  
In this case, you cut out the ballast, then take your hot wire (L) and tie it to either of the ballast's output wires, the blue or the red pair.  Finally, you tie the neutral wire (N) to the other color pair.  This has the advantage of not requiring you replace the tombstones (although they're cheap if you get them online) and not having to mess with adding more wiring.  To echo what I said about the single-end installation, I've seen nothing that says one end or the other of the tube needs to be L or N, but it might be marked on the bulbs themselves.

A visit to the local home improvement centers had no options whatsoever, so this time I went to search on Amazon.  They had a four pack of double-end lamps that were frankly more than I wanted to pay, but they had good reviews and to be honest, I was pretty tired of the problem.  I have a dark corner in the shop that needs new bulbs and this looks like it will get me there with the minimum of blood, sweat and tears.  

This blew entirely too much time over the last several days - and since I'm retired, I know I have more time than many of you.  The bulbs are supposed to be here tomorrow.  With luck, they'll be here well before 6 PM and I'll be able to get right on it.


  1. I have a bunch of 48" tubes of LEDs that are direct, drop-in replacements for fluorescent tubes, got on Amazon. Threw away the boxes, so I don't remember what brand, but they are available. No re-wiring, they run off the old ballasts and voltages. I used them in a dozen cheap 'shoplight' fixtures I had in the shop.

    1. I think the two ended bulbs work like that. I could replace the fluorescent tubes in the bad fixture without removing the ballast - except the ballast has failed. I'm getting four bulbs, so I could try them in another fixture to verify that works.

  2. It is reasonable to want to change those bulbs when we have no real idea what technology light fixture might be set to replace it in 13 years?

    I don't think so. When a ballast has gone bad, I've found it cheaper to buy a whole fluorescent fixture than just a ballast. I splice the new ballast into the old existing fixture to save work.

    I use normal 120 VAC screw-base LED "par" parabolic spotlights in the $6 small clamp mount reflector for shop task lights. Better brightness, better color, no power brick, and cheaper than "LED lights".

    I've made lights for the mill from LED spot bulbs from Wal-Mart. Base goes into a weather resistant rubber socket made for temporary construction lighting, with the mouth tightened with a ty-wrap. Around the neck of the bulb is a shaft collar from Tractor Supply. Supplied setscrew tightened gently to keep bulb in place. Elsewhere on collar, tap a hole for a 3/8" bolt. Unthreaded bolt shaft sticking out goes into dial indicator hole in cheap dial indicator mount arms.

  3. I use normal 120 VAC screw-base LED "par" parabolic spotlights in the $6 small clamp mount reflector for shop task lights.

    I have the clamp on reflectors on the big tools, but they have LED bulbs because the 100W incandescent bulbs are long gone. 100W is sufficiently brighter than 60W that I prefer them. There's still never too much light under the mill's headstock.

    I have three of the hang-from-ceiling type shop lights in the garage and when one of their ballasts died, I got a two lamp LED light just like it from the "bulk and bundle store". It was $35 and is nice and bright. I figured leaving the hanging hardware and power cord out of the box ought to make it cheaper, right? Noooooo. Fewer parts make the lights more expensive.

  4. How hateful of you to say:

    "Remember that this is 120 Volts AC and 120 kills more people than any other voltage widely distributed. If this is out of your comfort zone, don't do it."

    Instead, you should have just told them:

    "If you voted for Hillary or Gillum or Abrams or Romney, don't worry about the voltage."

    Do us all a great service...

  5. Re incandescent bulbs, about a year ago, I got 25-30 75-100 watt incandescent bulbs for two bucks at an estate sale. I use them in fixtures that are not used much, and replacing fixtures don't make much sense.

  6. No worries about L vs. N. While it is true that LEDs are polarity sensitive and work only when they are fed hot on the correct leg, these receive alternating current. That means that they turn on and off sixty times per second. Some people are sensitive to this flicker, but I notice it only when I look for it. It's interesting to think that if you could feed them 120 vdc you would double the perceived brightness and cut their life expectancies in half.
    Most Christmas LED strings use three wires for two circuits. Every other LED turns on in the opposite half of the AC sine wave, masking the flicker.

    1. I've never dissected a LED tube light, but I have pried open some of the regular LED bulbs after they failed (yes the cheap ones do fail, I think it is the other components, rather than the LEDs themselves that pop) and they have a somewhat sophisticated power supply that includes a full-wave diode bridge rectifier, filtering, and a voltage regulator IC which is specifically designed for this service; meaning they are running on DC and do not flicker.