I recently sought opinion on what I should do about the 5 foot 58w T8
magnetic ballast type fitting in my utility room. The problem was that
it was switched by an occupancy switch (PIR), to allow hands free
switching when walking in and out of the room with hands full.
The options were - leave as is (the tube's heaters were being hammered,
by regular starting), change to an LED strip, or change the magnetic
ballast for an electronic one. When it is on, t is not on for long, so
no big advantage for LED. I decided on the latter option (E-Ballast)and
managed to find an electronic ballast for £7.60 delivered and fitted
I was half expecting the series connected PIR not to work and having to
modify the light to allow it to charge up, but it worked fine without
any changes. Light comes on instantly, but with a slight strobing,
which clears within seconds.
I think I would have paid the extra £5 and bought a LED tube from
toolstation and just removed the ballast. You can just leave the ballast
in and use the shorting starter supplied but you don't need a ballast
with a led tube.
I wasn't convinced - The LED was only a little more than half the lumen
output of the 58w tube. Power economy was not a consideration, rather
the problem was tube life with all the on/offs. I have already swapped
all of the regularly in use lights over to LED and been happy with
them, but this wasn't a place where the consumption saving would be
worthwhile. The £5 extra cost, would have needed many years to repay
On Sat, 28 Apr 2018 11:46:34 +0100, Harry Bloomfield wrote:
Well said! :-)
Folk who keep advocating the "advantage" of downward only lighting of
the cheaper LED tube substitutes to compensate for their lower total
output, do so at the risk of neglecting the other excellent reasons why a
fluorescent tube offers a better lighting solution, lower glare index and
less self shadowing of the work area.
That's not to say that reasonably sized LED lighting panels can't offer
the same benefits but such an upgrade is an even costlier alternative to
simply upgrading the magnetic ballast of an existing fitting to an HF
ballast. The only troubling thing about that 7 quid *instant* start (with
brief flickery ramp up period) ballast is that it might be a simple HF
ballast without any form of lamp fault detection/protection to save the
more 'delicate' modern T8 tubes from premature wear.
The startup description echoes that of the cheap and nasty Chinese
electronic ballast that I replaced with a microprocessor controlled Helvar
ballast I'd bought for just under a fiver when I found myself having to
replace the 36W T8 tube for the second time in 18 months in a cheap B&Q 4
foot slimline batten fitting.
The Helvar ballast refused to run the failed replacement and only
attempted a single start on the original, leaving me to take a chance on
buying a new tube in the hope that my new fancy ballast was doing what it
was doing by design rather than by fault. As it happened, the former
proved to be the case and I note it applies some 900ms of pre-heat before
it strikes the tube into life with no flicker.
Unfortunately, because of the minimal mercury dosing, these tubes which
used to ramp straight up to full brightness, now have a similar run up
time to that of the mercury amalgam lamps used in CFLs. I guess that's
the price of "progress" in the world of linear fluorescent lamp
technology development that allows you to achieve the same lighting
levels as a 4 foot "40W" T12 tube in a magnetically ballasted fitting
(which actually used a total of 52W) from just the 36 watts consumed by
an electronically ballasted T8 tubed fitting. :-(
That 7 quid electronic ballast bargain might not be quite the bargain
you thought it was if you find yourself having to replace tubes on a
yearly basis. :-(
You can get LED tubes with a 300 degree spread eg
The ones I usually fit (as a retro tube fit not a new fitting) have a
140 deg spread.
And it is, as you know, horses for courses. It's nice to see someone
actually think about what they want/need with their lighting.
But I would still try to sell you LED:-)
On Sat, 28 Apr 2018 11:28:21 +0100, Harry Bloomfield wrote:
You're forgeting the log response of your eyes, halving the power is
only just perecptable. As I've mentioned before and the Aldi 5' 22W
2000 lm LED tubes I could barely tell the difference in light level
between the LED and previous 58W 5' florry.
The spread is as near as damn it identical to a florry as well.
With a light that isn't on for long (total) per day that's sensible,
but with a occpancy switched light the total on time per day can be
higher than one might expect. But with only a 20 W saving pay back
via power saving will still be long.
This is the gamble, if the LED costs three times the price of a tube
but last 4 times longer...
On Mon, 30 Apr 2018 16:06:47 +0100, Dave Plowman (News) wrote:
Use as in hours continously on or use as in switched on for 5 minutes
then off, maybe several times an hour for 10 hours/day. The tubes of
this thread were being killed by many switching cycles and use of a
That is certainly a low cost. The ones I have for my under cupboard
lighting in the kitchen are Osram, and cost several times that. But must
be about 20 years old now. And still the original tubes.
So if it is well made, should have a long life. Unlike LEDs which may
promise that, but not give it in practice. And of course the actual light
quality hasn't changed from what you're used to.
Dave Plowman email@example.com London SW
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