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Incandescent downlights to LED!

July 2015

Little more than two years back I started to look at solutions for replacing my lounge/kitchen area incandescent downlights. LED fittings were available then but were very expensive. The push for CFL lighting was at its peak, but I had too many misgivings about CFL's. I did want to reduce the power consumption and also seal the ceiling fittings against ingress of dust and fibreglass from the ceiling. Although I didn't expect there was much heat loss from the lounge space through the old fittings, any reduction would be welcomed. The six PAR80 reflector lamps in the combined open plan area took 575 watts of power in total.

LED downlight fittings are available now for a reasonable price. I chose the 12 watt Martec Genesis series which would be physically a more or less drop-in replacement for the incandescents. There are several similar types on the market now.

Martec Genesis brochure (pdf)

The driver unit for the lamp is not shown on the brochure, however it arrives ready to go, connected to the lamp assembly and with a short AC lead and plug on the primary side. The cord is removed for direct connection to TPS cabling. This lamp is IC rated meaning insulation may abut and cover the fitting. The existing holes in the plaster ceiling were 105mm, and the 110mm flange only just covers the hole. It works fine; the required cut-out is only 90mm. You can buy a larger flange. The lamp is rated for dimmer use, although that was of no interest in this case.

old and new lamps pic

These pictures simply show the old and new in situ. The new LED fitting maintains the simple, clean lines in the ceiling.

Light output

These Martec LED downlights are the "warm white" type (3000K) and Martec do make a 4000K option. You can get a nickel finish instead of the white. The colour-temperature is slightly more white than the original incandescents but it was only noticeable when some of each were operating together. The light output is impressive and although the lux readings directly below the lamp are not as great as were the PAR80's, it is more 'spready' . This is good since the old incandescents gave a hot spot directly underneath and the light reduced rapidly away from the lamp. Readings 'in the gaps' between lamps are now similar to and in some cases, greater than before. These LED fittings give a much greater overlap of illumination, which could mean you might be able to reduce the number of fittings.

Tests

A number were checked on the bench prior to installation.

Five of the lamps drew between 10 watts and 11 watts with a power factor of 0.92 on an AC supply between 230V and 235V. All slightly lower than the rated 12 watts, but with good consistency. Except one. It was drawing 13 watts. After 3 minutes of operation, it stopped with a slight burning odour. The driver had failed; not the LED's themselves. I removed the driver cover to have a look. Some components were burnt, but it was in no way repairable. Martec, via the supplier, did replace the driver unit. When the new driver was re-united with the LED fitting, it drew 10.85W, within the same range as all the others. As mentioned the power factor is good, the total harmonic distortion of current was 28%. I did note a fair amount of 100Hz flicker, which was greater than an incandescent bulb, but not as great as the old style linear fluorescent tubes. Still, if you are known to be sensitive to flicker, then there are lower flicker lamps out there. Check the website LEDBenchMark for unbiased test results of LED lamps.

I cannot attest to the longevity since the longest operating one has been going only 6 months.

Price

I originally ordered one lamp in 2013, to check it out. I bought from a New Zealand on line supplier and it cost me NZ$86.13 plus GST plus freight, which came to $102.63. Having decided to buy another 7 lamps some months later, I went looking for better prices and could not find these lamps at below NZ$92 retail in New Zealand at that time. I note that they have reduced a little now. On Australian websites, this lamp was selling for around AUD$32 give or take. I'm sorry rapacious New Zealand resellers, but if the difference in retail price is that great between Australia and New Zealand, then I will buy the Australian product. I would have accepted a somewhat greater price for the ease of purchase in N.Z and for dealing with warranties, but that difference was way too much. And note, way more than the issue of GST.

As it turned out, although there were many Aussie retailers selling the lamps, few were set up to export. However, I did find one. This is how the costs worked out in the end:

Although I did subsequently have to pay freight for the replacement failed driver unit, if that is included, the nett result was $47.43 per lamp. About half what the cost to buy retail in NZ would have been at that time.

Reduction of running costs

Taking the six lamps in the lounge/kitchen area, the lighting power consumption has dropped from 575 watts to 65 watts; a reduction of 510 watts. That means for every hour of operation we use 12 cents less power for the room lighting at the moment. For an estimated 4.5 hours per day of usage, averaged over the year, then the saving will be $197 p.a. The payback period will be less than 18 months, after which we will be saving. That is of course, trusting that no replacements become necessary.

In summary

LED lighting has come of age. I see no reason not to proceed with replacing all the oft-used and hungry incandescent lamps in a residence. LED's use even less power than CFL's equating lumen output and give a better light, evenly distributed and they start at full brightness. As for CFL's, dimming can be problematical and advice should be sought if required. The 'interim' CFL technology can be considered over.

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