LED replacement T8 tubes - Page 1
Forum section: electronics / general

author: Northy
author_rank: Regular Contributor
timestamp: November 25, 2020, 08:08:06 pm
content: I've bought one of these to replace a fluorescent tube in a standard fluorescent light fitting:https://www.toolstation.com/v-tac-t8-nano-plastic-led-tube/p79555I replaced the starter with the one that came in the box with the tube (I could see through the hole in it that it was just a link), turned it on and it worked.I found these instructions:https://www.v-tac.eu/images/certificates/Manual/VT-6072-instructions.pdfIs it best to re-wire it without the Inductive Ballast in there?Thanks,G

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: November 26, 2020, 02:28:40 pm
content: I do not see that the ballast adds anything to the function of the LED.Just another thing to go bad. And maybe to use extra hydro Watts (not many)I think that in Norway you use 240V and the ballast is just an inductor (again that is what I think) Maybe a capacitor alsoApparently you ballast is certainly not an electronic one.I do not see that you need any ballast in your use of a LED lamp. I think any required voltage control is inside the tube

author: SeanB
author_rank: Super Contributor
timestamp: November 26, 2020, 03:47:44 pm
content: Ballast left in simply adds supply inductance, and this is actually advantageous in increasing tube power supply life, as it will clamp the high voltage spikes present on the supply and limit the energy put into the power supply by them. Will dissipate some power, but likely only under 2W from the DC resistance of the wire, and as the LED tube runs at a very much lower current the voltage drop across the ballast left in will be minimal.I have done that, plus have had a few with the ballast removed (electronic ballast removed, magnetic ones left in) and the ones with the magnetic ballast left in are still running 4 years later, being on 24/7/365. The ones without had around half the LED tubes fail in under a year.One advantage to leaving the magnetic ballast in is that, if somebody replaces the LED tube with a regular fluorescent lamp, the end of the tube will not shatter on power application, as the filament is violently blown open circuit and arcs inside the tube. As they likely will not have turned off the power, not having to suddenly deal with a lot of shattered glass and blast right above your head is a good thing.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: November 26, 2020, 04:10:19 pm
content: Sean:ThanksHere in US most people were cheap and used electronic ballasts that make all sorts of RF noise, so they had to remove them when going to switch to LEDsI'll keep any good inductor ballasts I haveWally

author: Northy
author_rank: Regular Contributor
timestamp: November 26, 2020, 04:25:32 pm
content: Thanks for the replies.How do I tell what type of Ballast is in there?Thanks,G

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: November 26, 2020, 05:02:16 pm
content: The electronic ballast will not work with LED, so since your LED works, you have a big inductor which,as I understand, is the common one used in 240 volt environments.

author: Northy
author_rank: Regular Contributor
timestamp: November 26, 2020, 08:28:28 pm
content: Thanks.I've got a few more fittings I'm planning to do the same to, how can I check the ballast type?Thanks,G

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: November 26, 2020, 09:43:44 pm
content: Just google fluorescent ballast and they will have pictures.I don't think I have ever seen a 240 ballast. myself.Probably big heavy rectangular box 15+ cm long?

author: Northy
author_rank: Regular Contributor
timestamp: November 26, 2020, 09:51:33 pm
content: Yes, the one I looked in before changing the tube has a big white box in it.I guess that's old skool Inductive ballast?G

author: Northy
author_rank: Regular Contributor
timestamp: November 28, 2020, 09:21:43 pm
content: Well it looks like the replacement LED tube has failed alreadyG

author: james_s
author_rank: Super Contributor
timestamp: November 28, 2020, 10:22:53 pm
content: Quote from: Wallace Gasiewicz on November 26, 2020, 04:10:19 pmIt's not a matter of being cheap, magnetic ballasts were banned about 10 years ago so if you go to buy a fluorescent ballast in the US today they're all electronic.

author: Peabody
author_rank: Super Contributor
timestamp: November 28, 2020, 10:40:09 pm
content: I can't help with your T8s, but I had a house full (18 in total) of T12 tubes from about 1970. Some of the ballasts were running very hot, and all of them had PCBs inside. So I removed them all and installed LED tubes that connect directly to 120VAC. After two years they're all still doing fine. I think there was an advantage to doing this with T12s because the tombstones didn't need to be replaced or rewired. They were already non-shunted.I could have replaced the bad ballasts, or all of them, and I think the LED tubes that use them might have been a bit cheaper, but I just didn't want to have another part in there that could/would fail.

author: amyk
author_rank: Super Contributor
timestamp: November 29, 2020, 05:06:17 am
content: Some types of LED retrofits depend on the ballast to provide the current limiting; if you remove the ballast they'll burn out immediately.

author: james_s
author_rank: Super Contributor
timestamp: November 29, 2020, 05:21:58 am
content: While that's true, the instructions he linked for the tubes he purchased clearly state that it is recommended to remove the ballast and power the tubes directly.

author: Monkeh
author_rank: Super Contributor
timestamp: November 29, 2020, 05:46:09 am
content: Quote from: james_s on November 29, 2020, 05:21:58 amThey also clearly state not to modify the fitting. They are, like most, self-contradictory so they can deny a warranty claim for any reason.

author: Zero999
author_rank: Super Contributor
timestamp: November 29, 2020, 06:22:10 pm
content: It states in the data sheet it will work with, or without a magnetic ballast, but not with an electronic ballast.

author: Northy
author_rank: Regular Contributor
timestamp: November 29, 2020, 08:52:31 pm
content: Thanks for the replies.It seems the tube isn't goosed, it had just come out a little. It's a bit 'floppy', it might need a cable-tie or something round it.G

author: james_s
author_rank: Super Contributor
timestamp: November 30, 2020, 07:00:42 am
content: Quote from: Zero999 on November 29, 2020, 06:22:10 pmJust below that it says that powering it directly is recommended.I interpreted "do not modify the fitting" as "if installation requires messing with the wiring in the fixture don't do that yourself, hire an electrician" not "the fitting should never be modified under any circumstances". I suspect it's just a liability thing.