Back in the 1960s, when tubes were coming into service more and more, it was a widely held belief that they were more expensive to run than tungsten filament bulbs if turned on for short periods. It was said that most of the power they consumed was drawn during the 'strike-up' phase so if they weren't on for at *least* an hour, you might as well be using TF bulbs. Well, here we are 50+ years on and tubes are now very much old tech. What, with the benefit of hindsight, have the Panel to say about those old efficiency claims of the day?
That is what I was taught, but the calculation also involved wear and tear on the tube/starter/choke. I still will not install any sort of discharge lamp where it is liable to constant switching though.
They were never true. What was the case was that each switch-on wore the tube out by the equivalent of some hours running. The instant-start fittings which were common in the US suffered from this particularly badly. The switch-start used in most 220-240V countries much less so, but it was still a significant effect.
Yes of course they are more expensive. The light output is of a frequency that resonates with the thought patterns of muslim child molesters boosting their desires and leading to increased rumpy pumpy with our fine British schoolgirls.
The wavelength of the light could with the oscillatory nature means that peoples eyesight can be damaged and our poor British heroic houswives will not see rapidly moving kitchen equipment due to the "strobe" effect. This will lead to increased work for the NHS and if foreigners are subjected to the same risks, they will have an unfair advantage over white people as their fingers are darker and easily found amongst the ingredients for dinner.
If I were you, I would vote to get them all scrapped in favour of going back to incandescent lighting.
Importing whale oil and candle wax will be a tremendous boost for Britains economy, we could have trade deals with Japan in almost no time and the need for lamplighters would give employment to UK citizens once they have spent a year or so being trained.
By putting Whale oil lamps in operating theaters, the NHS would save £1,256.43P a week.
it was a misunderstanding. They used around 3x the current for the 1st 1-2 seconds during starting, but not 3x power. Starting added wear & tear to th e tube filaments. That's all. ISTR calculating the break even point many ye ars ago at somewere vaguely around a minute.
There was *some* justification for that belief but it wasn't electricity costs, it was premature wear of the thoriated cathode filaments due to the use of the cheap 'n' nasty switch starter.
Fluorescent lamps are discharge lamps which, in common with all lamps of that class, have a negative impedance characteristic which needs to be swamped out with a positive impedance wired in series. Their efficiency was so much better than the incandescent filament lamps they replaced that even with the losses of a resistive ballast on a 230vdc supply, they still gave off two or three times more light of a tungsten filament lamp.
However on AC supplies, it became possible to replace the ballast resistor with a ballast choke to provide a much less lossy positive impedance. The only downside being the inductive (lagging) current component this added to the load on the mains supply which increased the wattless amperage which, as far as the PSUs were concerned weren't wattless when it came to the I squared R losses in their transmission lines.
The solution was to mandate that a power factor correction capacitor be wired across the mains input of each light fitting using a tube with a rating higher than 20W in order to reduce this inductive loading to an acceptable level.
The filaments in fluorescent tubes were designed to run at full heat from the short circuit current of the ballast choke so that a simple neon heated bi-metallic switch could be used across the lamp as a crude starter. It worked but at great cost to tube life when used in frequently switched service.
When such lamps were only switched once or twice a day, there was no point in upgrading to a "Quickstart"(tm) transformer to give flicker free almost instant reliable wear free starting that would let you treat it like an ordinary filament lamp and still get the 7 to 12 thousand rated hours of life before it dropped to the 80% of design lumens point deemed to be the most economic point at which to replace it (generally several thousands of hours before it would actually fail to fire up properly).
Rather annoyingly, the newer T8 reduced mercury fill lamps will no longer fire up on a Quickstart ballast. For me, that meant shelling out on an electronically ballasted fitting from B&Q when the missus insisted on my replacing the older fluorescent fitting in our kitchen after we'd had the ceiling repaired post flat roof leak.
Unfortunately the B&Q fitting turned out to have been cursed with a 'Dumb' Chinese made ballast which caused the T8 lamps to fail faster than the old fashioned switch started units used to, simply on account of the fragility of "modern" inadequately dosed with mercury T8 "high efficiency" tubes due to the aggressive 'instant start' characteristic of the 'dumb' electronic ballast.
Luckily, the ballast failed about 18 months and two lamps later, forcing me to buy a proper microprocessor controlled replacement (about £4.70 delivered) which finally put paid to the problem of short tube life. Although I'm resigned to the unimpressive 900ms start up time (flicker free mind!), it seems we've paid a high price for our high efficiency, inadequately mercury dosed fluorescent tubes when I recall the 300ms startup and extremely long life of the older adequately mercury dosed T12 tubes of yesteryear running on Quickstart ballasts.
I know that fluorescent lighting is obsolescent technology biding its time for decent (and cost effective) LED based linear tubes to become worth investing in as an upgrade in areas where a diffuse source of bright lighting is required without having to go to the expense and faff of fitting LED ceiling panel luminaires, hence my replacing the ballast to carry on using the existing fluorescent lamp fitting in our kitchen.
Eventually, we might finally start to see 200LPW (more reliable) LED ceiling panels making an appearance in the next 5 to 7 years. I reckon I will have finally made my ROI on the existing light fitting just about then. :-)
Yup, from an electrical point of view was a load of nonsense at the time and still is...
If you think about it, say your tube draws 0.25A once lit, if you want to draw an hours worth of energy in (say) 5 secs, you will need to pull
3600/5 or 720 times the current. That'a 180A - or enough to trip a 32A circuit breaker instantly, let alone a 6A MCB or 5 amp fuse.
There is some truth in that there is extra cost to start the lamp but, that is down to accelerated wear on the starting filaments which will reduce the total lamp life (or at least the available number of "starts"). Since they were quite expensive at the time, there was a financial cost associated with that reduced life. So there was some sense in not turning them off for very short durations.
Probably more wrong now than then since modern tubes are far cheaper, and probably survive more starts anyway due to better control gear.
I meant much more efficient than the alternatives to fluorescents were then.
Yes, fluorescents still arguably have their place now, but that isnt for efficiency, it?s the much longer life of the long tube fluorescents than you can be sure of with leds.
2500'ish lumens from 24W vs 4000'ish lumens from 58W but probably the LEDs shine down where you want the light, so useful lumens per watt better than on paper?
It was rubbish unless the system was very badly designed as far as I know. There were of course tubes made that were only dual pigment which were not as bright as the later ones were too, which meant that efficiency was not that good. Brian
Well yes you had to use heaters and stir things up. I cannot say that \I've had tubes in quickstart electronic ballasts go more often than the normal starter switched ones. All in the end end up with black ends and the first indication is that in cold locations they can and do have trouble staying lit till they warm up. Brian
Might be cheaper to run but the frequency with which the bastard things in my kitchen (under-cabinet downlighters) need replaced outweigh the benefits . Even with replacing the starter at the same time as the tube I'm lucky if they last a few months* Meanwhile the monolithic monsters in the garage wh ich must be coming up for 20+ years old are still fine.
*I have looked into replacing the ballast but I'm buggered if I can find a simple how-to guide - it's all "if this then this otherwise this unless thi s". I might just skip straight to LEDs but find them a bit cold.
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