On Sat, 28 Apr 2018 11:46:34 +0100, Harry Bloomfield wrote:

ARW has brought this to us :
With half the lumens wasted.

In many cases perhaps, but not really here - the location needed direct
output from around 300 degrees of the diameter of tube, rather than just
down at the floor.

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. :-(

--
Johnny B Good