T8 B install in T12 fluorescent fixture.

Bellow picture 1 shows the T12 circuits which will be replaced by LED T8 B. There are two blasts, one controls lamp 2 and lamp 3, and another one controls lamp1 and lamp 4, (numbered from front to rear). The circuit of ballast 1 (A1) is similar to the circuit of ballast 2 (B1).
Below is the detail circuit of ballast 1 (A1).
A1 represents ballast 1, The sockets 2, 2R, 3 and 3R are connecting with ballast 1. Two blue lines and two red lines come from ballast 1 left end, and they go to socket 2 and 3. One black line and one white line come into ballast 1 right end from external power; and two yellow lines come out from ballast 1 right end and go to socket 2R only, and Socket 3R is connected by two gray lines. The detail about how two yellow lines from ballast 1 are connected to Sockets 2R and 3R, could be seen in Picture 2,
Picture 3 shows fixture left end, which shows how two yellow lines from ballast 2 (B1) are connected to socket 1, and socket 1 (tube 1) is connected with socket 4 by two gray lines. Red and blue lines from ballast1 (A1) are connected to socket 2 and 3 separately.
Picture 4 shown power inlet. Red line is separated into two black lines, and 3 white lines (maybe little yellow) are separated into to white lines.
The questions are:
(1) I am going to replace two T12 tubes with T8B, and remove ballast 1, and I will keep ballast 2 and its circuits as is, because ballast 2 looks OK. Is there any problem for such practice?
(2) After remove ballast 1 (A1), I am going to joint two red lines connecting with socket 2 (noted tube 2) and two blue lines connecting with socket 3 (noted tube 3) with Black line. Black line is cut from ballast 1 right side, red and blue lines are cut from ballast 1 left side. Is it OK?
(3) I also joint white line, which is cut from ballast 1 right side with two yellow lines, which are also cut from ballast 1 right side and are connecting with socket 2R (noted tube 2R). I will leave gray lines, which are connected Socket 2R and 3R, as is. Is it OK? I am little afraid about this joint, is there any other suggestions?
(4) Picture 4 shows fixture center power incoming. I am little confuse why there are three white (maybe little yellow) come in, then separate into two white lines.

Thanks for helps.

FIG 1. FIXTURE CIRCUITS

FIG 2. FIXTURE RIGHT END

Fig 3. FIXTURE LEFT END

FIG 4 FIXTURE CENTER, POWER INLET

 

You told us a lot but never asked a question. Is there something we can help you with?

If converting to LED the easiest is to remove the ballast(s) and wire according to your LED bulb's instructions. Usually you feed line power (120VAC) directly to the bulb.

 

It would not make any sense to change one ballast and leave the old one still in place.
Either change them both to electronic ballasts and T8 tubes or convert the fixture to LED tubes
for maximum performance and efficiency.

Fluorescent tubes will very soon be gone.
Now would be the time to upgrade the fixture.

 

Thanks, I am going to replace all T12 with LED T8B.
My questions maybe not clearly, question 3 states below:
My current fixture has two groups, each group controls two lamps. Now using one group containing two tubes set as an example.T8B instruction tell me that Red or Blue wires which joint with Live wire together, should go to each end of lamps separately. It means live line is combined 2 blue + 2 Red+1 Black, total of 5 wires. Yellow wires, which joint with neutral wire, should go to opposite end of each lamp, it means neutral line is going to combine 2 Yellow + 2 Yellow + 1 White, total of 5 wires, The problem is current fixture. neutral lines only go to one lamp socket by two yellow wires, then this lamp socket is wired to second lamp socket by two Silver wires (maybe colored Gray). see attached picture 2. So, neutral joint only combines 2 yellow + 1 White, total of 3, in addition to two silver wires which are connecting two sockets (I am going to leave silver wires as is). Does this connection equivalent to connect to each lamp opposite end? Or I have to cut silver wires, which connect two sockets, and connect silver wires at second socket to neutral joint to complete the neutral combination of 2 Yellow + 2 Silver + 1 White, total of 5?

Thanks

 

The exact wiring to follow is posted on the ballast.
You can post the part number if there isn't a clear diagram.

You're making it harder than it is.

Typically there is a white and black wire for 120v connection.
There is a red wire that goes to all four pins of the two sockets at one end.
There are two blue wires.
One goes to both pins of one tube at the other end.
One goes to both pins on the other tube.
You can combine both pins together or use one and insulate the other.

 

The ballasts in your picture are magnetic rapid start. They use two yellow wires to preheat the tubes.
T8 tubes will not run well on these ballasts due to lower mercury content.
You need electronic ballasts. They make them for 2, 3 or 4 48" F32-T8 tubes.

With electronic ballasts.... you can combine the two socket wires at the end of each tube.

 

There are two types of LED retrofit bulbs. Both are supplied directly with 120VAC. One type you feed hot to one end of the bulb and neutral to the other end. The second style all connections are made to one end of the bulb only.

 

Attached is the installation instruction of rapid start Ballast. Now, I am going to set four LED T8B in current T12 fluorescent fixture and bypass ballasts. First question is: May I put LED T8B in this original T12 fluorescent fixture?

From the installation instruction, there are two blue wires for one lamp and two red wires for another lamp. I am going to keep all wires from the socket, so each socket of one lamp end has two red wires or two blue wires instead only one red or one blue. So, there are four red wires and four blue wires to joint with black wire (live wire). To remove 1 of 2 red wires or blue wires from each socket seems little difficult unless cut/insulate one simply. The second question is: May I joint 4 red wires, 4 blue wires and 1 black wire together as one live line for 4 lamps? Neutral line is similar. The third question is: Considering there are two red or blue wires for each socket, If I have to remove one or cut/insulate one for good, which one I should choose or either one?

Thanks

 

You can completely remove both ballasts. Then the fixture is nothing more than a holder for the bulbs. When removing the ballasts I cut as close to the ballast as possible to leave the most wire attached to the tombstones. In most cases the wires are long enough to bring together for the supply connection. Super easy. Just make sure you wire properly for the LED bulbs you've got. I can say from experience that the bulbs let out the magic smoke if you wire them the wrong way.

 

Yes. T8 bi-pin lamps and T12 Bi-pin lamps use the same sockets.

Yes. I recomend a red wirenut.

It shouldn't matter. You can also cut the two wires and connect them together with a single longer wire if that is what you choose.

 

thanks.