HF ballasts for linear fluorescents
 

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:
http://i29.tinypic.com/2ikfvgz.jpg
The 'crack' in the tube at the top is a cobweb in case you were
wondering. It was full of dust.

I've also read http://wiki.diyfaq.org.uk/index.php?...scent_Lighting
(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

HF ballasts for linear fluorescents
 

Part timer wrote:
With an electronic HF ballast, the power saving would be a bonus to
increasing lamp life, better starting and ditching the nasty starters.

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

I've seen ebay item 250670139376

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

Philips recommend using short cable
lengths to one end of the tubes. What is the reason for this?

That seems to be a fairly common restriction on HF ballasts. Philips'
data sheet for that ballast is at
http://www.lighting.philips.com/gl_e...spec-touch.pdf
It 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.

something to do with 30kHz. How short is short?

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

Anything else I should watch out for apart from isolating the fitting,
double checking work, etc?

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.

--
Andy

HF ballasts for linear fluorescents
 

"Part timer" wrote in message
...
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:
http://i29.tinypic.com/2ikfvgz.jpg
The 'crack' in the tube at the top is a cobweb in case you were
wondering. It was full of dust.

I've also read
http://wiki.diyfaq.org.uk/index.php?...scent_Lighting
(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

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 he
http://en.wikipedia.org/wiki/Fluorescent_lamp_formats

S

HF ballasts for linear fluorescents
 

On Fri, 30 Jul 2010 12:09:29 -0700 (PDT), Part timer
wrote:

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?

Usually 1m for the "short" pair, 2m for the other. Only really an
issue if the unit is mounted outside the fitting (not unusual in
display lighting).

Anything else I should watch out for apart from isolating the fitting,
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.

HF ballasts for linear fluorescents
 

On Jul 31, 10:00*am, Peter Parry wrote:
On Fri, 30 Jul 2010 12:09:29 -0700 (PDT), Part timer

wrote:
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?

Usually 1m for the "short" pair, 2m for the other. *Only really an
issue if the unit is mounted outside the fitting (not unusual in
display lighting).

Anything else I should watch out for apart from isolating the fitting,
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.

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.

HF ballasts for linear fluorescents
 

On Jul 31, 10:00*am, Peter Parry wrote:
On Fri, 30 Jul 2010 12:09:29 -0700 (PDT), Part timer

wrote:
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?

Usually 1m for the "short" pair, 2m for the other. *Only really an
issue if the unit is mounted outside the fitting (not unusual in
display lighting).

Anything else I should watch out for apart from isolating the fitting,
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 theballastas they are longer than the
standard one.

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!