LED v CFL bulbs

[charles]

I haven't bought one, but CPC are selling 100w LED floods.

[ARW]

homeownershub is is the devils spunk.

[Scott]

What about retail suppliers? It seems to me the ones in Morrisons, Sainsbury's, John Lewis, Currys and Maplin are all warm white.

[Caecilius]

I think that's because the corn cob lamps use SMB chips, which are not as efficient as the COB chips used in single LED units.

[Harry Bloomfield]

Caecilius formulated on Sunday :

My experience of one unit, does not support that. I replaced a 36w double D light fitting with a new fitting installing in it, the cob LED I mentioned earlier. It produces a much better light in the area. The one issue is that being a much smaller light source, it tends to dazzle a bit. It has already outlived the operating time I would expect of the double D tube, where it would begin to dim.

[alan_m]

Not if you include the extra green stealth tax on your utility bills used to discount those CFL's in retail outlets.

[Fredxxx]

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[tabbypurr]

whoosh

[Brian Reay]

I've come to the conclusion it is a matter of 'perception'. We've found LEDs pretty well hopeless in a domestic setting- nothing like the claimed 'equivalence' to ordinary bulbs. Conversely, a friend swears by them- although his sitting room (for example) has a huge number of LED lights inserted in the ceiling (at least 20) whereas we have one central light in a similar sized room.

We do use them in our motorhome but we accept a lower level of light there.

[ARW]

36W DD?

[Tim Watts]

Nope - you can easily get lamps upto around 5000K (very cool white)

LED Hut are good in that respect - pick a bulb and a power, and there'll generally be a choice of 2-3 colour temperatures.

[Tim Watts]

That's why you have to go online and stop bother with high street shop which often sell utter junk.

[Vir Campestris]

I just bought a couple from B&Q (yes, I know, but I needed them _THEN_ to go with some new lights).

Much to my surprise they take a second to come on. And are completely flicker free.

Andy

[Harry Bloomfield]

ARW formulated on Sunday :

Mistyped - 38W DD

[John Rumm]

No, you can get cool white and daylight as well.

(I got some cool white GZ10 spots for the kitchen the other day)

[John Rumm]

1440 lm is probably close enough for those applications (i.e. it will match a GLS 100W past its first flush of youth).

Many light fittings these daya will have multiple lamps anyway, so the need for 100W equiv in one lamp is less of an issue. (for example, my dining room has a 3 lamp fitting - 30 x 60W equiv LED works very well for that)

[John Rumm]

The better quality LEDs seem to make more realistic equivalence claims (I note the LEDhut now often claim an equivalent against a halogen tungsten rather than a GLS). I used to find the CFL equivalents were often wildly overstated though. Also they would quite often make a comparison to a 60W "soft tone" lamp, which was a rarer type of filament lamp with lower light output than a regular GLS.

[John Rumm]

Much of the key to success seems to be finding a reliable brand that has decent quality products. Some of the very early LEDs I tried were poor, did not last well, and had poor colour rendition.

[Michael Chare]

One difference is that with a pendant LED bulb very little light goes upwards. I have a theory that lamp shades should last longer because the bulbs do not give off much heat.

I only buy 2700K bulbs, not 300K bulbs as they are to white (IMHO).

I have had a number of failures.

[Johnny B Good]

====snip====

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 s**te "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. :-(