School me on Fluorescent Fixture Conversion to LED

sween1911

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So I have 4 fluorescent fixtures in my shop. 4-foot tubes. As the original bulbs went bad, I converted to LED tubes. Working great except for one fixture. It would occasionally blink out. Thought tubes were bad. Started crackling and smelling funny. Ah, gotta be the ballast. Fortunately I was down there and unplugged it and pulled it down before it started smoking up the place. I have since learned that one can rewire a fluorescent fixture to use the LED tubes exclusively.

- If I rewire the fixture to bypass the ballast, can I continue to use the LED tubes I have, or are those only made to step-down the voltage from the ballast, and I have to use LED tubes made for direct-wire fixtures?

- Anybody got a good guide or info on how to do the rewire?

Thanks!
 

Lynx_Arc

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There are differing designs of these LED replacement tubes on the market some are drop in not requiring anything at all, others are direct wire that require rewiring the fixture essentially bypassing the ballast and there is some that you can do either with. You need to figure out from the manufacture (may be included information with the tubes) which type you have.
One other issue is for the ones that will work with the ballast there is two types of ballasts out there the newer ballast type is electronic and these tubes may not work with both types of ballasts again you need to consult the information for it.

Likely there are instructions either included with the tubes or available on the website. One other issue is how the tubes are wired as some that are not dropins require rewiring and they could have both power leads on one end or one on each end of the tube the ones with both power leads on one end may require new connector blocks to be purchased.
 

KITROBASKIN

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Sounds like a good time to research a more efficient option to replace the fluorescent replacement LED's for that one faulty fixture.
 

jtr1962

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Sounds like a good time to research a more efficient option to replace the fluorescent replacement LED's for that one faulty fixture.
I've been doing this every time a ballast goes. No point replacing it when for about the same price (or less) I can get LED tubes which use maybe half the power and give the same amount of light.
 

LEDphile

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You need to start by determining which of the 3 (4) types of replacement tubes you have. This information should be marked on the tube or the tube packaging. The types are
  • Type A (these use your existing ballast)
  • Type B (these require the ballast to be removed and connect directly to the AC line)
  • Type C (these use a replacement LED driver
There is also a "Type A+B" that can be used with a ballast or connected directly to the AC line.

For Type A replacements, you also need to make sure that the replacement lamp is compatible with your existing ballast - T12 and T8 lamps use different ballasts, and there is no guarantee that a T8 retrofit will work with a T12 ballast.

Some more info and some wiring diagrams are in the below white paper from the US DoE (which is targeted at the fixtures commonly found in office buildings, but has information applicable to all fluorescent retrofit applications)
 

idleprocess

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The ballast-compatible tubes are there for convenience, however they're dependent on the ballast remaining operational - a wear component that adds nothing to the system. If you've got the means and are comfortable performing the work I recommend bypassing the ballast altogether; mains-powered tubes are also either the same price or slightly cheaper than ballast-compatible tubes. I also suggest selecting tubes that are compatible with "single end" rewiring for greater simplicity.
 

turbodog

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You need to start by determining which of the 3 (4) types of replacement tubes you have. This information should be marked on the tube or the tube packaging. The types are
  • Type A (these use your existing ballast)
  • Type B (these require the ballast to be removed and connect directly to the AC line)
  • Type C (these use a replacement LED driver
There is also a "Type A+B" that can be used with a ballast or connected directly to the AC line.

...

I've converted 5 (4) tube fixtures to led bulbs from t8.

Used the a+b bulbs, but converted directly to 120vac.

On the rewire:

1. cut leads to ballast (close to ballast)
2. remove ballast
3. bundle all wires from one end of the fixture to your neutral (usually white) wire
4. bundle all wires from other end to hot (usually black) wire
5. insert bulbs
6. done

this is assuming your bulbs are:
1. compatible with 120vac
2. made to be driven from each end

You're taking the top picture and converting to the bottom one.

1644249249028.png
 

turbodog

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I'm gonna make another suggestion. If you install them, and like them, buy a few spares. If/when you have a failure, the CRI, tint will match. This is an area that's changing a good bit so no guarantee getting similar looking bulb output a year from now.
 

turbodog

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...

- If I rewire the fixture to bypass the ballast, can I continue to use the LED tubes I have, or are those only made to step-down the voltage from the ballast, and I have to use LED tubes made for direct-wire fixtures?

...

If they were working with the high voltage from the ballast... my gut feeling is that they will work with plain 120vac. Read the bulb, maybe it says on there. Lookup bulb model and see if you can find specs.

Otherwise just toss the ballast and buy new bulbs.
 

idleprocess

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I've done about 100 retrofits these at the local makerspace with single-ended tubes using the following method:
1644251526436.png


While the lengths and arrangement is specific to their fleet of quad-tube T12 fixtures, the single-ended wiring is immensely simpler - and uses less wire - than both ends. You will need non-shunted T8 tombstones for both ends; the unwired ends are just there to hold the other end of the tube, which on some designs will conduct mains voltage.
 
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