fluoro light starting - Page 1
Forum section: electronics / projects

author: Harvs
author_rank: Super Contributor
timestamp: April 18, 2015, 08:57:48 am
content: I replaced a couple of twin T8 fluoro's with new fittings that have electronic ballasts.The ballasts have quite a bit of difficulties starting the two tubes. They flicker once, and if the tubes don't start then they don't do anything more until switched off for 15 sec. After a few tries they usually start ok. With only one tube in the fitting, it always starts fine.So I'm now wondering if the tubes get any easier to start after a few weeks of use, or should I be looking for new ballasts?

author: Evil Lurker
author_rank: Regular Contributor
timestamp: April 18, 2015, 10:02:12 am
content: Difficult to say. Some tubes are not rated for instant start ballasts and for those that are the more hours of usage a tube has and the more times it has been turned on and off the harder it is to start due to wear and tear on the filaments on either end. It is also possible that the eletrolytics in the ballasts might not be up to snuff. It might even be were you need to install a thermistor in your ballast... some PCBs have spaces for them pre-drilled and silkscreened even if they are not installed by the manufacturer.

author: SeanB
author_rank: Super Contributor
timestamp: April 18, 2015, 02:53:20 pm
content: Make sure the fittings are grounded, as the electronic ballasts need the case to be grounded to help with the HF starting of the tubes. It might be that the ballast case is insulated from the metal plate the tubes are mounted on by a paint coat that actually insulates as well, so check the case of the ballast is actually connected to mains earth, and that the grounding tab on the base is screwed down tight enough that it makes contact through the paint with the mains earth lead. Otherwise take the fittings back as not suitable, and if buying tubes stay away from the no name PRC ones. The Indonesian made Phillips along with the Singaporean ones are fair, the USA ones are all over the place ( actually made in Mexico now) and if you get the Polish made ones buy the rest of the case and keep it.I have had quite a few fittings where I bought the fitting complete, put it in and then 2 years later bought the 2 magnetic ballasts, the 2 starters and holders and wired them in after the ballast blew, keeping the same tubes in there. Some have made 8 years now, but the magnetic ballasts have done decades of work, only failing when the terminals fall off from the plastic going brittle.

author: Harvs
author_rank: Super Contributor
timestamp: April 19, 2015, 06:33:00 am
content: Thanks, I'll trying cleaning all the earths first and see how that goes.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 19, 2015, 07:02:51 am
content: Let me guess, low/no mercury tubes..??Tim

author: SeanB
author_rank: Super Contributor
timestamp: April 19, 2015, 09:36:22 am
content: Yes, but not the Alto junk you get in the USA. Alto means stops working soon in any use. Most low mercury will be a nice pale pink when struck.

author: briselec
author_rank: Regular Contributor
timestamp: April 19, 2015, 07:01:34 pm
content: I'd be having a close look at how they have been wired if it starts fine with just one tube installed.

author: Kjelt
author_rank: Super Contributor
timestamp: April 19, 2015, 08:30:47 pm
content: Doublecheck if the wattages of the ballast and lamps match.On the Philips ballasts there are two pairs of wires that MUST be kept short as in shorter then 20 to 30cm. The other pairs are non critical. This is mentioned on the driver.Indeed also check earthing and they should start within a second (requirement for emergency lighting where good ballasts conform to).If you have some cheap unknown brand ballast then all bets are off.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 19, 2015, 10:46:26 pm
content: ..or throw away the ballasts and fit T8 LED tubes...