58w fluorescent on a PIR, with mag-ballast in a utility room.
The tube finally refused to strike up last week, so I installed a replacement tube, all back to normal now, but I am wondering whether to adapt it to LED tube or fit an E-ballast. It is a room we often walk in or out of with hands full, so I replaced the switch with an occupancy switch (PIR). Once triggered, it remains lit for maybe ten minutes and maybe comes on three to five times a day - so economy is not a high priority, so much as tube life. It has gone through maybe three tubes, in around 20 years.
I am not keen to replace the complete fitting, but I have a small stock of 3.5w BC LED's. I could perhaps cheaply DIY adapt the fitting, with
Occupancy sensors driving flouresents is not ideal, but if you just accept you'll get shorter tube life, and they won't have run up to final output before you finish using the room, then it can be done. I have 3 x 58W fluorescents in my internal garage where the freezer is on occupancy sensor. I replaced the ballasts with electronic instant start (that's real instant start, not even a few milliseconds preheat), and they're on a 20 min timer. I think they're on their second tubes in 15 years, although the total 'on' duration wouldn't come close to merit that. If I was doing it now, I would use LEDs of course.
A decent electronic ballast will not only give longer tube life, but faster start up too.
Despite the claims for long life, I'm not convinced replacement LED bulbs with built in electronics do all last the claimed life except under lab conditions.
I'd hope they are. But in this case with an existing fitting, I'd bet a decent electronic ballast and tube will last longer. Added benefit is you already know how much light it gives (and the quality of that light), unlike with LEDs where you have to guess until you've fitted them.
Long enough not to go off while you are in the room, and add a bit for good measure. The power rating would only be around half, so any wasted 'on' time costs correspondingly less anyway. Frequency of switching has no effect on LED life, and probably just a tiny amount on the driver, which you can ignore.
I always used to set the 2D CFL communal light in flats etc to 15 minutes even if they only needed two minutes worth of light. My reasoning was that the cost of paying for relamping was more than the cost of the electricity.
Some of the better manufactures do have proper spec sheets for their LEDs. Most of what I fit in NHS, schools offices etc have already been designed by the manufacturer to meet a certain lighting level.
That brings us back to the quality of light over time. The LEDs I have fitted do not dim as time passes like fluorescents do. Mind you a bit of a wipe with a cloth could help out some of the lights.
Now if only street light LEDs were yellow............
There is an LED chip which is a very close match for low pressure sodium lights. Some years back, I made a model streetlamp for my nephew, so I searched through the spectra of yellow LEDs to find a good match for low pressure sodium and came up with an almost perfect match in a power LED. Also used a red LED to similate the LPS run up, with the yellow LED coming on slowly (but speeded up as real ones take 9 minutes which is beyond the attention span of a 4 year old).
Yes - but I'd guess those are all proper LED fittings. Not a LED designed to replace a tungsten bulb directly. To me, those are in the same class as CFL. A very badly engineered idea.
Not true with the T8 tubes and microprocessor controlled HF ballasts compared to the ancient Quickstart ballasts used with the, now sadly, obsolete T12 tubes (250ms versus the 900ms of the electronic ballast).
I guess the T8 tubes need a hell of a lot more Baby like care over their startup phase than their more rugged T12 ancestors which lasted two or three times longer on a Quickstart ballast than with a simple switch start one, typical of most domestic kitchen lighting.
The problem is that for a given LPW lamp design, their cooling requirements become ever more demanding with higher lumen ratings. They can't shed their waste heat at 200 odd degrees C like an incandescent can, it's more like an 80 deg C limit tops. The higher lumens output lamps of any given LPW generation are likely to overheat if fitted in a less than fully ventilated fitting designed to cope with 100/150W incandescent lamps.
The older 81LPW lamps were usually ok up to 810Lm in most open shades any higher lumens output lamps of this generation needed really good ventilation to avoid death by overheating. Today's 125LPW 1500Lm "100W incandescent equivalent" BC light bulb as sold by Home Bargains and other retail outlets can now be safely used in standard luminaires that were previously unsuitable for the earlier generation of LED lamps.
My interest in LPW improvements is less to do with electricity savings and more to do with lamp savings in locations that are crying out for a decent 100 or 150 watt incandescent's worth of lighting power. At the moment, with those 125LPW lamps, we seem to be at the stage where we can now fit a "100W incandescent equivalent" in a standard fitting with little fear of premature failure.
Which is the problem. I must be unusual in wanting a decent lighting level when actually needed. And here, that would mean a minimum of old 100w tungsten or larger, if a single light.
A complete LED luminair with non-user replaceable LED lamp is not always a badly engineered idea (provided it's reasonably well engineered). A classic example being a 30W LED floodlight alternative to the 'standard'
300W linear halogen bulbed floodlight that more or less demands a trip up a ladder once or twice a year to fiddle about replacing a blown bulb until the PIR switch itself blows up leaving you thinking you might as well make do with a 60W porch light until decently efficient LED equivalents to the 300/500W security flood lights finally materialise at a less than eye watering price. One of those is likely to outlast a new build house! No more repeat trips up that damned ladder in the depths of winter any more. :-)
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