I have a new ceiling light to install. It comes with 28W (the maximum rating of the fitting), 370 lumens, G9 lamps but I would prefer to use LEDs that are at least as bright.
As the LEDs will be 5W or 6W, I assume that heat won't be an issue?
Any potential problems I might have missed?
And can anyone recommend a source of decent 400+ lumens G9s?
Well clearly if you stick a 6W LED in a fitting that is good for 28W, the fitting isn't going to have a problem with heat.
The only problem is whether the LED will have a problem (they *really* don't like getting hot).
It won't cause any problems for the enclosure designed to withstand the fierce radiative heat of quartz halogen lamps.
But it might shorten the working lifetime of the LED bulbs considerably if their working temperature is close to 100C. Capacitors boil dry after a while.
Going off at a slight tangent, some lampshades are rated for 60 watt tungsten or 11 watt (I think) energy saving bulbs. I can understand that they might overheat if you put a larger conventional bulb in them, but why the hell should they mind having a higher capacity energy saving bulb? Has someone just quoted a bulb with (alleged) equivalent light output without thinking logically about it?
Thanks. That's what I expected, though was concerned that the G9 might have some localised hot spot where all of the 6W(!) (7W as it turns out) might be concentrated.
The 'shade' has plenty of large holes in it.
Probably, at least for open lampshades with free air flow.
However, the glass globe ceiling mounted ones will rapidly kill a same nominal output CFL/LED bulb by cooking its control electronics once the temperature gets close to boiling point for the capacitor electrolyte.
Glass shade and an incandescent bulb are quite happy getting pretty hot.
It is still hard to get any energy saving lamps with the same light output as 150W and 200W incandescent lamps for a sensible price.
Industrial grade ones are available but not very pretty.
The problem isn't so much about the rating for the luminaire (in particular the bulb holder itself - plastic or ceramic) so much as it is about the maximum temperature the lamp can tolerate within the confines of said luminaire.
A tungsten filament lamp typically converts more than 95% of the input energy to 'waste heat' (infra-red and convected/conducted 'waste heat') and is designed to cope with the relatively high temperatures produced (circa 200 deg C). The luminaire's rating is based on these temperatures (60W for a plastic bulb holder, 100 to 150 W for a ceramic one - 100W rating being the limit due to other materials used by the luminaire and its level of ventillation).
CFLs and LEDs both use electronic ballast circuits built into the lamp base which have much lower temperature limits (silicon devices max out at
150 deg C and high temperature electrolytic caps at 105 or so deg C).Since the silicon devices aren't perfect lossless switching devices, they generate additional heat which requires their immediate environment to be a few tens of degrees lower than their maximum ratings in order for the heat to be conducted/convected away.
Whilst good quality electrolytic capacitors don't normally generate much waste heat in a properly designed circuit, these too need to be operated in an environment several degrees lower than their maximum rating (the lower the better since this extends their lifetime hours rating significantly beyond the typical ten to twenty thousand hours at max rated temperature).
I haven't seen any 'environmental temperature' ratings mentioned as part of the specification of these CFL and LEDs. No doubt the manufacturers do have such limits in the 'spec sheet', they just don't bother 'troubling the end consumer' with such pesky details. CFLs have a definite 'optimum temperature range' for the actual fluorescent tubes themselves (50 to 60 deg - significantly higher than the 30 to 40 deg for conventional linear tubes).
Allowing for the required temperature gradients between the electronic components used by the lamp ballast circuitry confined to the lamp base and thermal contact to the luminaire acting as a 'heatsink', I'd be very much surprised to see an environmental temperature limit much above 70 deg for the lamp base of an LED lamp, considerably lower than the 150 to
200 deg for a tungsten filament lamp.Rather conveniently, the 11W or so LED/CFL equivalent of a "60W" tungsten lamp offers enough temperature reduction in most cases sufficient to allow the use of such "60W Equivalents" in a 60W rated luminaire without undue overheating risk. Unfortunately, this is often an unknown parameter as far as most luminaires are concerned (no temperature versus wattage figures being readily available - it's down to the end user to take test measurements if they want to determine this all too critical factor in regard of the effect on LED lamp life).
I'm facing a similar conundrum with an external "60W rated" porch luminare I recently fitted over our front door as a stop gap to tide me over the period between now and the appearance of 200Lm per watt security lamps finally appearing in the stores (the lousy 90Lm per watt lamps are about to be obsoleted any time soon - yet another 12 to 24 months later than Cree and Philips were promising would appear some 18 to 24 months later nearly 24 months back with their 300Lm per watt laboratory samples).
I'm trialling a 20W CFL in the new porch light which replaces an original porch light I fitted some 30 years back but which failed and was sidelined by a 500W halogen security light over twenty years ago. I fitted the security light quite high up to give better coverage and less light spill. Unfortunately, whenever I need to change a burnt out lamp or even replace the whole unit (I'm on my third one this time round), I need to set up a three piece ladder to gain access and the novelty of 'working at height' has worn rather thin.
I'm determined that the next security light will be a 200lm/W 25W LED that will last me out for the remainder of my days, hence the 'temporary porch light' to silence the XYL's moaning about trying to park up on our drive in darkness.
The CFL is, as you could predict, rather slow in ramping up to full brightness at this time of the year (about 5 minutes run up time). Nevertheless, it does seem to reach full brightness.
Since it's only twenty watts, the protracted run up period can be sidelined by leaving it switched on until bedtime. The fact that it seems to be surviving 6 to 8 hour sessions ok suggests that I might be ok with a modern 15W LED, especially if it's a 200 Lm/w type rather than an 81 to
90 Lm/w type typically on today's shop shelves (even less 'waste heat' to be dissipated - the main benefit rather than just the higher lamp efficacy).The *real* benefit of the later 200 and 300 Lm/W LEDs isn't the reduction of lighting energy costs compared to the 67Lm/W of CFL and 80 to 90 Lm/W of today's LED, it's the reduction of waste heat that has to be handled by our existing luminaires.
The simplest way to demonstrate this benefit is to assume the replacement of a "60W 810 Lm" 10W 810 Lm LED (in reality, a 75W 240v lamp
- 60W is the American 120v 750 hour rated 810 Lm standard) with a 2000Lm
10W LED. For the same input wattage you get over a doubling in light output meaning even less of the input energy showing up as non-productive waste heat in the luminaire.The former 10W 810 Lm is emitting about 1.5W as useful light[1] leaving
8.5 watts to heat the lamp and the luminaire, just doubling up the lamp's efficacy means 3 watts goes to useful radiation in the case of a 10W 1620 Lm LED lamp, leaving only 7 watts as heat for the same 10 watt input power. If all you need is an 810Lm 5W lamp then the waste heat drops from 8.5 watts down to 3.5 watts.The next generation of LED lamps will make a lot of existing light fittings (luminaires), that aren't suited to the current generation of LEDs, entirely adequate to the new task in hand, neatly avoiding any need to upgrade them for use with the currently available LED lamps.
[1] This figure is just a best 'guestimate' I've used to provide example figures to demonstrate the effect of improved luminous efficacy on luminaire (and hence lamp) temperature.
Perhaps a bit late now for your purpose, but a CFL floodlight that I got from Aldidl about 3 years ago (they are in store every so often) and put on my neighbour's back wall does come on to full brightness almost immediately. It's 23W, fixed, about 4000K at a guess. Aimed well down so that it doesn't 'spray' all over the place.
As for LED type, I'd use the twin-head sort here as they're more 'aimable' -
2x5W, say 450 - 500lm each, would do for my requirement.
I plan on eventually replacing the 20W 810lm CFL with a suitable 360 deg radiation pattern 15W LED lamp[1]. The porch light fitting I bought from Toolstation ( Code 12199 Victorian Style Lantern Black 60W ES) as shown on this web page:
is basically just a stopgap remedy until I can replace the halogen security light with a modern 200lm/w 25W LED version in another year or two's time which, like its predecessor, will render said porch light redundant. I chose the 'cap down burning' version simply to minimise the heating effect on the lamp base electronics. Unfortunately, this conflicts with the typical 270 deg radiation pattern of most of the cheaper LED lamp types making my choice of lamp a little more critical than usual.
The fitting is only 'ventilated' by four small 'breathing holes' in the base designed to prevent moisture accumulation so it's a bit of a heat trap, relying essentially on conduction to pass the heat from the internal air to the exterior environment via the glass panels and metalwork of the fitting, not the most sympathetic of designs as far as LED lamps are concerned.
The original porch light was fitted first, followed by the 500W halogen security light. When that porch light finally fell to bits a few years afterwards, there didn't seem much point in replacing it so I just removed the 'dangly bits' to make it safe, leaving the twin core flex dangling, ready for the 'replacement' (having isolated it from the lighting circuit connection to make it electrically safe).
At the time, I wasn't expecting it to remain a "Feature" for the next two decades but that was how it was until just a few weeks ago. The white cable was only used as a 'draw string' to pull the end of the 1.5mm FT&E it had been crimped onto (I'd left a few metres of extra slack under the bathroom floor boards for just an occasion as this).
Not being made from cheap mild steel, I expect the new porch light to last a lot longer than its predecessor did so once I've got the new security light sorted, it's main use will be simply to provide a 'decorative back up' to mitigate any future problems that might arise with the security light. At least as a 'Decorative Feature' it's a significant improvement over the previous one of a 'dangling length of white flexible cable'. :-)
[1] I reckon a modern 15W 200lm/w LED lamp will produce no more than half the waste heat of the existing 20W CFL so ought to be able to run cool enough to realise its full life expectancy whilst providing a 3 to 4 fold increase in light output raising the porch light's current efficacy from 'barely adequate' to 'nicely adequate'.For the time being, 'barely adequate' is a damn sight better than 'no light at all' so it suffices until modern LED prices drop out of the stratosphere in a year or three's time. Hopefully, it will be relegated to 'decorative back up' status a year or two before then.
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