On Sun, 22 Oct 2017 01:28:42 +0100, John Rumm wrote:

====snip====

I found the filament style 60W equiv lamps
to be very good a true match for light output and a pretty good CRI.

That'll be on account the 806Lm lamps "Wattage" rating is based on the
more efficient American 120v 750 hour tungsten filament lamp type than on
our less efficient UK 240v 1000 hour lamp type.

It's taken quite a few years longer than promised by Cree but we're
finally seeing LED lamps with efficiencies above the best on offer of
81Lm per watt of the past five years now raised to somewhere in the
region of 120 to 130Lm per watt.

I've been seeing 12W 1500Lm GLS LED lamps in Home Bargain stores for the
past 5 or 6 months now at the £2.99 mark (both 3000K and 6500K colour
temp ratings and in LES and BC22 forms). I'm not entirely tempted by the
brighter alternative to the 806Lm LES lamp fitted (cap down) in our porch
light since the opaque base blocks a bigger portion of the required
downward illumination, for cap down burning, than the existing lamp.
Also, they're still less than halfway to the 300Lm per watt promise of
the 303Lm per watt lab samples of three (maybe four?) years ago, where
they suggested that it typically took 18 to 24 months to go from lab to
shop shelf - they're at least 18, if not 30, months behind schedule on
that 'promise'.

The important benefit of doubling the efficiency from 80Lm per watt to
160Lm per watt is the reduced waste heat temperatures when running a
1600Lm 10W lamp compared to running the older 806Lm 10W lamp of
yesteryear, allowing decent levels of light to be provided in poorly
vented light fittings using the higher efficiency LED lamps where the
older type would most likely have suffered shortened lifetimes from
overheating. The reduction in energy consumption being merely a nice and
welcomed side effect.

Heat has always been the enemy of LED lamps. The most elegant way to
solve this problem is not to incorporate bigger heatsinks and/or cooling
fans (at least not in the case of GLS types) but to improve efficiency so
more of the input energy is converted into wanted illumination energy and
less into unwanted heat energy. Cree (and to a lesser extent, Philips
lighting) proved it was possible to almost quadruple the efficiency of
the 81Lm per watt LED which has been the mainstay of LED GLS lamps during
the past 4 or 5 years.

A good CFL to LED upgrade strategy is to replace EoL CFLs in areas where
you'd prefer the instant light characteristic of filament and LED lamps,
saving those CFLs in places such as hallways and landings for a later
upgrade where they're typically left on between dusk and bed time.
Smaller landings can typically be illuminated by those A shape 6W 470Lm
BC22 / LES lamps available in Poundland and any chandeliers currently
using 40 or 60 W tungsten filament candle lamps can usually be cheaply
upgraded with 3 or 5 watt LED candle lamps also on sale in Poundland.

IIRC, you can now buy the classic "60watt" 806lm LED 'bulb' in Home
Bargain stores for just a few pence more (£1.39 afaicr) so it needn't be
an expensive upgrade even at this early stage of the game provided you're
just interested in replacing you existing ageing CFL fleet with slightly
brighter LED alternatives.

Whilst on the subject of lighting, I'd like to make an observation about
linear tube fluorescent lighting. For some years now, it has been
possible to purchase slimline fittings with electronic ballasts for use
with T8 4 and 5 foot tubes (ideal kitchen lighting imo). Unfortunately,
you had to go out of your way to find a store that actually stocked such
light fittings[1].

Most places, lighting specialists and departments in larger stores
alike, seem blissfully unaware of this advance in fluorescent lighting
technology and will cheerfully foist an old fashioned magnetic ballasted
lamp with, horror of horrors, the cheap and nasty starter switch which
shortens tube life to as little as a third of what's possible with a half
century old "Quickstart Transformer" magnetic ballast technology[2].

A couple of years ago, after getting the kitchen extension flat roof and
ceiling repaired, the missus strongly insisted that I replace the old
semi-slimline 4 foot batten fitting which I'd upgraded to Quickstart"(tm)
by shoehorning a QS transformer into the fitting (literally unwrapping
its outer steel casing to allow me to squeeze it in!) some 15 years
previously.

Since I wasn't able to make a case against replacing the old fitting, I
started checking out local sources and discovered the cheapest electronic
ballasted 4 foot fitting in B&Q of all places (14 quid versus the 7 quid
or so of a cheap switch start magnetic ballasted unit) which I duly
purchased and tested against the old fitting to verify their respective
energy consumptions[3] before fitting said replacement onto the virgin
plaster boarded ceiling of our kitchen.

The supplied tube only lasted about a year before failing completely,
forcing me to go out to our local Lighting specialist shop to make a
distress purchase, albeit at just a third of the SCEWfix price. It was
only a day or so later that it occurred to me to check out Tool Station's
prices and discovered that I'd missed out on an even saner price - ah
well, you live and learn.

Anyway, the replacement tube worked just fine for about another year's
worth of service before the cheap Chinese made electronic ballast started
to emulate similar tube failure symptoms last week. I left it to the
following day to try the trick of reversing the tube, not really
expecting to improve things. Much to my surprise, normal service was
restored. However, I had a sneaking suspicion the relief was only going
to be short lived and, sure enough, it went back to its dim flickering
resolving into full lumen output flashing like a disco strobe light just
a few hours later.

Eventually, out of curiosity since I suspected the real culprit was the
cheap 'n' nasty Chinese ballast, I left it to carry on to what I expected
would be self destruction (something a properly designed and manufactured
electronic ballast should never do). I have to say, was not disappointed
in this since just a few minutes later the light extinguished with a
muffled fart coming from the fitting suggesting it was going to go bang
in a big way if I hadn't been handy to the wall switch to turn it off
before it got the chance to short out and blow the ground floor lighting
fuse.

At this point, I was seriously considering bypassing the ballast and
replacing the tube with an LED based 'ersatz' tube but the main problem
with the affordable types is their indifferent efficiency forcing a lower
power limit and a downward concentration of light output compared to a
proper fluorescent tube.

Although a couple of those 1500Lm Home Bargain store lamps could replace
the 2500Lm fluorescent tube, they couldn't match the lighting quality
demanded by a kitchen (shadowless and even illumination) so I started
googling for electronic ballasts that didn't cost more than I'd paid for
the whole fitting (way far too many of that type of ballast - overfeckin'
priced! - to be found on the interweb).

Eventually I found a decent brand, Helvar, at the right price (£4.47
with free delivery) on Amazon to tempt me to place an actual order for
one. The only snag with the free delivery option being the longer
delivery times. This order is scheduled to be delivered next week between
the 24th and the 28th. With any luck, it might even turn up tomorrow
(Monday) but I ain't holding my breath.

One of the reasons why I've gone to the extra faff of ordering and
fitting a replacement ballast rather than buy and fit an overpriced LED
based linear batten fitting is that I suspect the original tube wasn't as
terminal as that ****e "Shangyu Bright-Lighting Electric appliance co.,
Ltd" ballast had implied the first time round.

For a mere £4.47 investment, I get the chance to fully realise the
capital invested in the current tube and, quite possibly see some
additional useful life out of the original, even if only as a lower light
output 'spare' to tide me over a complete tube failure as determined by
the new ballast calling time on an EoL tube to prevent overheating and/or
uneconomic operation of a below par tube.

LED lighting technology has come a long way during the past ten years or
so (even if it does seem to have stagnated somewhat during the last four
years) but there are still some situations where it doesn't quite match
the older technologies for quality of illumination such as the classic
fluorescent batten light fitting in the domestic kitchen where even and
shadowless illumination is of prime importance.

[1] I tried all the usual Electrical trade shops before chancing on the
B&Q example and only one claimed to stock such a fitting which proved to
be a barefaced lie when I turned up at their counter in person to lay
claim to my prize. Indeed, none of the usual suspects even so much as
stocked spare electronic ballasts for upgrade or repair of existing
fittings. The only sources all seemed to be on line e-tailers asking
stupid money for the product (circa fifteen quid and up).

[2] A "Quickstart Transformer"(tm) is an auto transformer with cathode
heater taps at each end of the winding which is wired across the tube. On
switch on, the original series ballast choke allows almost the full mains
voltage to be applied across the tube and the transformer which applies
voltage to the cathode filaments warming them up to full emission causing
the tube to strike within two or three hundred milliseconds of switch on
which drops the tube voltage to its normal running voltage due to the
volt drop in the ballast choke from the tube current. The tube, of course
lights up about as quickly as the 12v 35W halogen downlights in our
shower room each fed by an electronic 12v 60W rated "Transformer" with no
sign of the flicker normally associated with fluorescent lighting in most
of the general public's mind.

The heaters now receive a reduced heating voltage which elevates the
filament temperature a little above the marginal minimum produced by
cathode bombardment alone to avoid cathode stripping and loss of its
emissive coating. Switch start further aggravates cathode coating loss by
sputtering on each start cycle, a process largely absent in the case of
the quickstart transformer circuit.

Using a Quickstart transformer makes a real difference to tube life in
situations where it gets frequently switched on and off, otherwise, when
it is only switched on and off a couple of times a day and left running
for several hours at a time, the cheap and cheerful switch starter based
circuit will give nearly as long a life as the QS type.

[3] The only downsides to continued use of the venerable Quick Start
circuit is the reduced lamp efficacy compared to an HF electronic ballast
and the fact that compatible T12 tubes are becoming harder to source and
modern T8 tubes simply won't start up in a QS fitting.

I'd known about the benefits of high frequency AC to fluorescent tube
operation for the past four decades or so, so was curious to compare the
power consumption of the older 40W T12 4 foot tube in a magnetically
ballasted QS fitting and the newer slimline 36W T8 4 foot tube in an
electronically ballasted fitting.

After allowing about half an hour or longer warm up time, the figures
were 36 watts exactly for the electronic fitting and 50 to 51 watts for
the older magnetic ballasted fitting. It was too close to call on
effective illumination levels to say which, if any was the brighter.
However, I was happy with the result which helped to mitigate the small
sense of loss at finally putting 'Old Faithful' out to pasture.

Hopefully, the Helvar ballast will restore my faith in HF electronic
ballasts once more. I suppose I should have guessed that B&Q's 'cheaply
priced' electronically ballasted fluorescent batten fitting would prove
to be of the lowest quality possible. :-(

--
Johnny B Good