It seems the wiring for a LED tube to replace a fluorescent is not a one size fits all. You have to follow the diagram which comes with the tube. With the one I fitted it stated that with a magnetic ballast it could be left in place, the only thing you needed to do was to replace the starter with the one provided with the tube.
However it will reduce energy used by also removing the ballast.
The line and neutral pins are both one end of the tube with the one I fitted, it seems some do have line and neutral either end, BUT NOT THE ONE I FITTED so copying the diagram for a random tube could cause all sorts of problems.
The supply is one end and the other end is a short circuit, so unless the two ends are wired in series putting the tube in wrong way around is a direct short. I thought the new starter was a simple fuse, however on testing and opening it was not, not sure what was inside the new starter, looks like a resistor but value would be too high for lamp to work, so must be some other resistor looking device with a resistor colour type code.
The replacing of the starter with a fuse is required to get full power to end pins, but once done putting a fluorescent tube back in will likely blow the heaters before the fuse, also if the tube was to start since the ballast is removed there is no current limiting device.
Although I did replace a 5 foot thick 64 watt fluorescent with a 24 watt LED tube on hind sight this was not as good as it first seems, one there is the danger of a replacement being fitted wrong way around, or a non matching replacement, and second the lumen dropped from approx 6000 to 2400 which is a massive drop. Lucky where fitted I did not need the 5500 lumen of the new 58 watt fluorescent tube with a HF ballast so I got away with it.
However assuming the size was selected correctly in first place, the cost of swapping the fitting for a twin fitting to get 4800 lumen and the cost of two LED tubes make it uneconomic to replace fluorescent tubes with LED, only if the tubes were too big to start with is there a case for swapping with LED. So in a corridor it may be good to replace fluorescent for LED but in an office it would not be a good idea.
However having a mixture of LED and fluorescent also as I have shown has problems where starters are incorrect, or ballast is missing or the tube is otherwise wired not as expected, so with a LED tube with around 100 lumen per watt and fluorescent at 95 lumen per watt and using a HF ballast around the same life then the health and safety aspect means simply swapping fluorescent for LED tubes is not an acceptable risk in my mind.
Yes I did it, to replace my 65 watt tube needed the ballast to be changed for one designed for a 58 watt tube which would mean I would need to remove the whole fitting to do that, but I could alter wiring without removing the fitting and there was a pile of crafting supplies of my wife's under the lamp, so I selected the expensive but easy way out. However I do worry about forgetting what is in the fitting and how it has been rewired so on my todo list is returning it to a fluorescent with HF ballast.
