HF ballasts for linear fluorescents

[Part timer]

Got a fitting with a pair of T8 58W tubes that sometimes take a while to start. I've had enough of swapping starters with variable results, and the ends of the tubes go black too soon for my liking. I took the cover off this evening to see what's inside:

'crack' in the tube at the top is a cobweb in case you were wondering. It was full of dust.

I've also read

(thanks to those who contribute to this!) I assume that what I currently have is EEI (Energy Efficiency Index) D since the fitting was fitted in the early 90s (could have been made earlier) and not marked with such information. With an electronic HF ballast, the power saving would be a bonus to increasing lamp life, better starting and ditching the nasty starters. I've seen ebay item 250670139376 with an A2 EEI rating which drives both tubes (I know that if one dies, they both go out until the dead one is replaced). On the label, Philips recommend using short cable lengths to one end of the tubes. What is the reason for this? I assume something to do with 30kHz. How short is short? Anything else I should watch out for apart from isolating the fitting, double checking work, etc?

PT

[Andy Wade]

Close to unity power factor too and no flicker, so yes, well worth doing.

Ah, I've bought from that guy: highly recommended.

That seems to be a fairly common restriction on HF ballasts. Philips' data sheet for that ballast is at

gives figures for maximum capacitance between the wiring to the tube ends and to earth at one end (p.2) - so that must be it. See note 5 on p.6 for practical interpretation.

See above. FWIW I've had no problems with lengths up to 200 mm or so.

Make sure you get a good earth connection to the ballast's earth terminal, as well as to the case.

A reel of RS 183-9225 is worth getting if you have several fittings to re-wire. It's the pukka 85 deg. rated 'fluorescent fittings wire' and works well in the push-fit connectors. Saves a lot of messing around trying to re-use the old wiring.

[Spamlet]

While you are at it, recalling another recent thread, you might think of looking into T5. There is a lot of useful info about the various types here:

[Peter Parry]

Usually double checking work, etc?

Usually a simple job, you may need to drill a hole for a self tapping screw to hold one end of the ballast as they are longer than the standard one.

[Part timer]

Thanks to all who replied. Purchase made. I realised about the screw hole spacing but I'll have the fitting down to do the conversion anyway. I won't be bothering with T5 just yet.

[Part timer]

Got up nice and early this morning and took the fitting down. Stripped out the Thorn iron lumps (2kg worth), capacitor, starters (left the starter sockets disconnected). Dusted it all down, drilled the extra hole to suit the electronic ballast's mounting holes and reused two of the screws from the old ballast. I worked out the best strategy to reuse the original wires with 3 choc-block connections where needed. Double checked it all including earthing, put the tubes back in and fired it up. No waiting 3+ seconds while it canes the tube ends, no buzzing and no flicker. Magic!