How to bypass ballast for T8 4ft LED tube ?

According to the diagram Red and Blue goes to the extreme ends of each T8 tube and Yellow is common and goes in the center for both tubes.

White and Brown goes to the mains power line.

2 styles of LED conversion I know of . 1- both positive and negative on same end of tube ( other end dead ) or 2-Positive on one end and negative on other end . Either way , incoming black goes to one prong and white goes to the other prong .

There are LED bulbs that operate with the existing ballast but I would avoid this style . Ballasts are the weak link , especially with cheap fixtures .

Here, is this what you meant?

Right now, I have only 1 LED tube and it should be enough, because in the kitchen, there are already 2 fluorescent tubes on the same fixture close by. So I need to know what to cut and what to connect for only 1 LED tube. But it would be better if this LED tube is located on the left fixture which doesn’t have the ballast (on the left of the one with ballast, because it’s right over the stove).
You already saw the right side of the left fixture on the 4th picture (with the 2 black wires in the thumbstone).
On the left side of the left fixture, there are 2 white wires, that are connected to the ballast of the right fixture to the 2 red wires on the right side of the ballast.

So what should I do?

I’m sorry your last post was a bit confusing. :nerd_face:

I have upgraded/replaced T8 bulbs before at the shop. Basically the ones we bought, do not require the ballast. We removed the ballast. We had to buy some non shunted tombstones for the Black (HOT) and White (NEUTRAL) prongs that make electrical contact. The regular tombstones used in florescent tubes are shunted on most of them as the electrical contact is made across the entire tube to the other end. Most of the LED versions only make contact on one side, at least the double prong versions of these LED lights anyways. You can use the original shunted tombstone for the plastic prong side to simply hold the T8 in place as no electrical contact is made there. For the business end where the metal prongs are, you need non shunted tombstones so your Black (HOT) and White (NEUTRAL) are separated and not shorted like a shunted tombstone. It really wasn’t too difficult to upgrade the lights.

It all depends on the bulb setup you bought.

https://www.amazon.com/LEDwholesalers-Non-Shunted-tombstone-fluorescent-replacements/dp/B00DZIGJX6

I added some photos of the existing installation, so you can better understand. Please look at https://photos.app.goo.gl/5EnX5CT4CnNdvKsf2
On the first picture, you can see the right fixture with the ballast. The second picture shows both fixtures, right and left. On the 3rd picture, you can see well the left fixture, with no ballast. It is on the left fixture that I would like to install the led light, because it is over the stove. The 4th picture shows the left thumbstone of the right fixture. The 5th picture shows the right thumbstone of the left fixture.

No one can help?

The fact is that this a quite small forum and the people here are almost entirely flashlight enthusiasts and have limited knowledge about your T8 setup.

I would highly recommend you try electronics.stackexchange.com since it is a more appropriate forum for your problem + it has a vast user base.
I’m sure the folks there would solve this for you within a matter of hours if you provide them with all the relevant information beforehand.

:slight_smile:

thank you!

Without physically being there to see your wiring setup, I’m afraid no one can give you an accurate assessment on your situation.

It is more of an electrician topic , here is a good site :

It seems your picture is invalid.And I think if you choose this LED tube light with double ends & single end ,there will be no need of ballast. You can remove your ballast, and the installation will be simpler.
https://www.slideshare.net/JoanZhong2/t8-type-b-double-ends-single-end-glass-tube

Don’t forget he will need a non shunted tombstone for the hot and neutral side.

i think it has one wires :nerd_face:

With the ballast that is correct. Once you remove the ballast, all you’ll have left is the mains. This will leave you the Hot and Neutral wires. Since the tombstone in the fixture is a shunted one, you can’t plug the mains into it as it will short out. So you replace a non shunted tombstone on the side where mains needs to make contact to the two active terminals, either on the left or right side, depending on how you position the T8 tube.

You are making this way too complicated. You could simply replace the existing bulbs with two LED bar lights that go for under $2 each from an overseas vendor (14-21 days delivery) and power them with a 24W universal driver for $5 https://www.ebay.com/itm/Universal-DC-12V-24W-60W-2A-5A-Switching-Power-Supply-Driver-for-LED-Strip/112734551939?hash=item1a3f80bf83:m:mkrAxSGdbsuetAX3GPhLGYw It will fit neatly where the existing ballast is located and the output for the two bar lights would be equal to using two T-8 lights at a fraction of the cost. The new T-8 bar lights that plug in the existing holder but don’t use the ballast are just strip lights with a driver enclosed in the tube. I see a set of four of them go for $39 on Amazon whereas one bar light is only $1.39 postpaid 50CM 12V 36 LED 5630 SMD Hard Strip Bar Light Aluminum Rigid White 50CM 12V 36 LED 5630 SMD Hard Strip Bar Light Aluminum Rigid White W1L2 for sale online | eBay Of course, if you can scavenge an old 12V 2A DC converter (look for one with an efficiency rating of IV or V on the label) it is even cheaper. I picked up many a converter from of the local second hand store for a buck or so. I’ve used them as undercounter lights, closet lights, and garage lights with good results.

Ok without reading any more of the confusion on an old topic I am an electrician in my state. No offense to anybody but there are way too many indians and not enough chiefs in this clan making things way too hard.

Did you ever figure this out since it’s an old topic?

Not for anything but ripping out the ballast and changing a tombstone from a shunted to a non shunted is the simplest retrofit. I’ve already had to do that at our shop. 16 T8 fixtures. It’s super easy.