T8 LED - One tube working upside down? Stumped

[buening]

I'm probably having a dumb moment, but I am installing 4ft T8 light fixtures (new LED ballast-free). The first 4 footer installed and bulbs work correctly. Onto the 2nd one and one bulb will only turn on when the bulb is facing up against the fixture. The other bulb in that same fixture works correctly.

I have spun the tombstone 180°, both on the L and N ends independently and its still the same. I'm using Sylvania bulbs and have swapped known-working bulbs and its still the same, so I know its not a bad bulb.

The tombstones have jumper wires connecting both sides, to eliminate the non-shunted issue. Inside the fixture a single hot wire goes to one end of the fixture and single neutral to the other end. Both L ends of T8 bulb are on the black wire end, its just one bulb only works 180° out.

What am I doing wrong??

 

[PCustoms]

What am I doing wrong??

Swap the tube end for end?

 

[buening]

Tried that too. Still only works facing up

 

[buening]

 

[BurtEggley]

have you downloaded the LED manual and exactly followed the wiring configuration? The bulbs I chose to buy were direct wire (aka ballast free). The manufacturer had three or four wiring diagrams, and I wired each fixture exactly to their specs. The bulbs I chose did not have a L and N side, although I marked the fixtures for future users if bulbs are changed. These bulbs were non directional, meaning no L and N. The only real instruction was to be sure the dead spot was up and the LEDs down. All worked fine. So some bulbs are directional and some are not. I do not know what Sylvania does. Also, there are bulbs out there that require an ELECTRONIC ballast and not a magnetic ballast. Those bulbs will not work in a direct wire fixture. I chose direct wire because it is more efficient than the ballast replace kind, but it takes a little more work pulling out the old ballasts, rewiring, and adding a fuse to protect the next idiot who comes along.

 

[buening]

 

[buening]

have you downloaded the LED manual and exactly followed the wiring configuration? The bulbs I chose to buy were direct wire (aka ballast free). The manufacturer had three or four wiring diagrams, and I wired each fixture exactly to their specs. The bulbs I chose did not have a L and N side, although I marked the fixtures for future users if bulbs are changed. These bulbs were non directional, meaning no L and N. The only real instruction was to be sure the dead spot was up and the LEDs down. All worked fine. So some bulbs are directional and some are not. I do not know what Sylvania does. Also, there are bulbs out there that require an ELECTRONIC ballast and not a magnetic ballast. Those bulbs will not work in a direct wire fixture. I chose direct wire because it is more efficient than the ballast replace kind, but it takes a little more work pulling out the old ballasts, rewiring, and adding a fuse to protect the next idiot who comes along.

Yes, the manual for bulbs show L wire going to one end and N at other end, with jumper wire to each bulb end. That is how the fixture is wired.

No ballast required and says so on the bulb. Bulb also says Type B

Strange part is other fixture works fine with both L bulb ends at one end and N at other, both bulbs facing down.



I'm thinking something is bad with the tombstone wiring. Other bulbs turn on facing up as well as down, but this one bulb only works facing up.

 

[buening]

Figured it out. Jumper wire on tombstone was broken. Goodness

 

[BurtEggley]

good catch