Fullscreen HTML5Med Res (??MB)HTML4

Replace Mercury High-Bay Lights with LEDs by Ross Tester and $ave $$$ Back in February last year, we told you how we’d not only brightened up a dingy corridor by replacing halogen downlights with purpose-made LED fittings, we expected to significantly reduce our power consumption in the process. Now we’re at it again – this time replacing power-hungry mercury discharge warehouse lights. T he LEDs we used in that feature came from Tenrod – and recently, another press release arrived from them telling us about their industrial high-bay LED fittings. Having quite a few high-bays in our building and knowing their shortcomings, we were immediately interested: could these achieve the same sort of savings and utility as we managed last time? High-bay? For those who may have spent their lives cloistered in an office or outside in the sunshine, we’d better explain the term “high-bay”. They’re the light fittings of choice in warehouses, etc and typically come fitted with a 400W mercury discharge lamp. We’ve shown a photo above of one of the high-bays in our warehouse (on left), alongside a new LED high-bay, to siliconchip.com.au demonstrate what we are talking about. The most obvious difference is the size and shape – the mercury high-bay is significantly higher but has a more parabolic-shaped reflector. The LED high-bay is squatter and has a wide, cone-shaped reflector. Incidentally, the mch higher apparent brightness of the mercury high-bay in this photograph does not tell the full story. Partly this is due to the fact that the camera sees much more light from the reflector because the lamp radiates over much wider angles than the LED array. In fact if you look directly at both lights (ie, especially on axis), the LED array looks dramatically brighter – nearly blinding, in fact! As their name suggests, high-bays are designed to be mounted high up – usually near the roof (most industrial areas don’t have ceilings!) more than five metres off the ground. They’re large (typical high-bay fittings have a 300-400mm diameter reflector and are perhaps 500mm high); they’re heavy (due to the ballast circuitry almost invariably fitted to the top of the reflector); they’re quite expensive (typically between $250 and $300 each) and, typically, they take quite some time to come up to full brightness from turn-on (perhaps 10 minutes or more). However, when they do come fully on, they are very bright and with the right reflector, produce a good spread of light. Waiting, waiting . . . But perhaps the worst feature of the mercury high-bay is that if power is interrupted, even for a moment, they extinguish but take even longer to cool down and then restart. So a warehouse or production area can be plunged into blackness for quite a number of minutes before you have any light; February 2014  89  Mercury High Bay AdvanceQuez LED High Bay AdvanceQuez LED Flood Power Rated 400W 120W 130W Measured 404W 118W 133W Brightness Dedicated light meter (Digitech QM1587) 550 lux 3060 lux 13620 lux Multimeter with lux measurement (Digitech QM1580) 760 lux 4330 lux 19980 lux Photographic light meter on “EV/ ambient” setting (Minolta IV-F) 7.7 EV 9.9 EV 12.1 EV 22000 typ. >9000 10800 Lumen output (manufacturer’s data) “Real world” measurements comparing the three lamp types. These were all taken on-axis at 4 metres, after 15 minutes to ensure full warm-up. The apparent discrepancy between the lumen output of the mercury high-bay and the LED models is due to the more diffuse pattern of the mercury. In fact, on the floor below, the LED light pattern is significantly brighter to both the eye and to instruments. EV, or exposure value, is more a photographic measurement but being related to aperture and f-stops, gives a relative measure between the light sources. Both LED fixtures were “cool white” with a colour temperature of 5600-6500K. not good when there is machinery or moving equipment! We just mentioned a moment ago that they are normally fitted with a 400W mercury lamp. Thankfully, these have quite a long life because (a) the bulbs are expensive and (b) getting up to change lamps can be quite a chore with a scissor-lift typically being required. But it’s not only the lamp that’s draining power: the ballast gets rather warm and you are paying for that heating. We measured a couple of mercury high-bays and found them to draw around 404W each. Multiply this by the number in a typical warehouse – anywhere from a dozen or so up to perhaps 50+ in a big installation and you can see that you are up for many kilowatts of (now very costly) power. If those lights are on for 14 hours a day (by no means uncommon) just one of those high-bays could be costing more than $800 per annum (at current business electricity rates of about 40c/kWh). How to reduce that power? What if you could get at least as much – and probably much more – light output from your high-bay at a little more than a quarter of the consumption? Obviously, that means a quarter of the cost of electricity as well. We are talking LED replacements Definitely not the reflector shape you’re used to with the older mercury high-bays – and at 510mm diameter, these LED high-bays are much wider. But you can enjoy significantly more light output AND save a lot of power into the bargain! One other big advantage the LED high-bay has over its mercury cousin is significantly lower UV output – normally not a factor but certainly can be in some installations, such as indoor sporting venues. 90  Silicon Chip for your existing lamps. Once again, these were supplied by Tenrod – and they had two different styles available for us to look at. LED high-bay One is a straight swap for the ubiquitous mercury discharge high-bay. The fitting looks somewhat like a traditional high-bay, albeit with a simple conical reflector rather but instead of the mercury lamp (and ballast) it has a 50-LED CREE fitting, with a rather impressive 9000 lumen ouput. When we say bright, it’s too bright to look into without ending up with these dark patches in your eyesight, which persist for quite some time! At 6m distance from the light, illuminance is 401 lux, dropping to 168 lux at 10m. Naturally, at 10m you get a much wider beam spread and is much more suited to the high-level use you’d expect in warehouses, etc. On top of the LED high-bay is what looks like a traditional mercury ballast but is in fact simply a large heatsink. The 230V mains power supply is separate, on an attached lead. But in effect, the LED high-bay really is a drop-in replacement for the mercury high-bay. It doesn’t have the long “power up” time of mercury lamps – for all intents and purposes, it appears to be “instant on”. Measurement does show a slight increase in level over time but you’d be hard-pressed to notice it. And it comes on immediately if turned off and back on again. No more stumbling in the dark saying undeleted expletives! LED life is rated at 35,000 hours – that’s four years of 24-hour-a-day operation. LEDs being LEDs, less frequent use would undoubtedly stretch this out much further. Specifications of this lamp fitting are shown above. Using the same electricity rate as we did for the mercury high-bays, you would save more than $500 each year for each high-bay you replaced. But even better – in a typical warehouse you should be able to use fewer LED high-bays, maybe 20-25% less. One futher point: all the comparisons are taken with clean lamps. We’ve found that over time mercury highbays become very dusty – both the globe and the reflector – which further reduces light output. LED floodlight The second fitting is much smaller – siliconchip.com.au The light dispersion from the fittings is dependent on the position of the light source within the reflector, the amount of collimation (much more in a LED than in a discharge lamp) and shape of the reflector. These three photos were taken from identical distances under the lamps and shows the dispersion. The left pic is that of the mercury vapour (discharge) lamp – wide dispersion and the lamp source at (or close to) the focal point of the reflector. The middle shot is that of the LED high-bay – a rather different pattern from a rather different looking reflector. The right pic shows the LED floodlight, a different shaped reflector again but with much wider dispersion pattern. The LED high-bay is intended to be mounted up high – in large warehouses, for example, it could be ten metres or more off the ground. in fact, it looks more like a replacement for a traditional halogen floodlight. And so it is, being designed more for outdoor use with an IP65 rating (total dust and low-pressure water protected) and an even higher 50,000 hour rating on the LEDs. Unlike the single-wattage high-bay, the floodlight is available in 30, 130 and 200 watt versions, with luminous flux of, respectively, 2500, 10,800 and – wait for it – 15,800 lumens! That’s for the cool white versions, warm white are significantally lower. While intended for vertical installation on a wall, (again, being LEDs) we would assume that it wouldn’t get upset at being mounted at other angles or positions. The same cannot be said for halogen bulbs – mounting them at any angle off horizontal can (sometimes dramatically) shorten their life. You might wonder why we included this LED fitting in this review, given the fact that we were basically looking at high-bay replacements. Well, from experience we know that in warehouses and industrial premises, there are a lot accidents where (for example) a forklift mast takes out a high-bay – especially if there is limited headroom. We reasoned that these floodlighttype fittings, with a height of only 375mm, could be an ideal replacement. Add to that the polycarbonate/ aluminium construction and the IP65 rating and they could be used virtually anywhere. Even the larger 200W model siliconchip.com.au is only 400mm high. The smaller (and cheaper) 30W model would be ideal for filling in dark corners and, for example, the spaces between pallet racking where the main lights can’t quite get to. The verdict These LED replacements are not cheap, especially if you have a large area with large numbers of mercury high-bays to replace. The savings are undoubtedly there, simple maths will tell you that you’d be well in front after a few years. Replacing mercury high-bays, even with the saving, is a significant capital cost for most organisations – but we believe a well worthwhile one. If you’re talking a new building, it’s a no-brainer! And if you suffer damage from wayward forklifts (or anything else!) and/ or have limited headroom then once again, you really should be looking at the LED floodlight fittings. Where from, how much? Both the high-bay and LED floodlight came from Tenrod Australia, 24 Vore St, Silverwater NSW 2128. (02) 9748 0655 www.tenrodlighting.com.au The high-bay retails for $650.00+gst, while the 130W LED Floodlight sells for $740.00 +gst. For 10 or more there SC are discounted prices. Here’s the IP65-rated (ie, external use) LED Floodlight, with its Cree 50-LED array clearly visible (go on, count ’em!). It really is very bright, as our temporary blindness can attest to when taking the photos! While this is designed to replace vertically-mounted wall floodlights, we see no reason why it could not be used horizontally inside or out, especially in areas with limited headroom. In fact, the multi-position mounting bracket suggests it is intended to be used at any angle. February 2014  91