Although light-emitting diode (LED) technology has been around for several decades, it's only recently started to become a player in mainstream commercial lighting applications. As the number of manufacturers offering LED-based luminaires continues to grow, it appears this technology has reached its potential for almost any lighting application.
LEDs claim many advantages over traditional lamps (i.e., incandescent, HID, and fluorescent), namely durability and longevity. Despite these benefits, the most obvious challenge with LED lighting is its high initial purchase price tag — a reality that undoubtedly stems from its newness to the market. Like all new technologies, however, the cost is expected to eventually decrease to a more competitive level.
Aside from price, there are several other pros and cons to consider when it comes to working with LEDs. As an electrical contractor looking to install LED-based luminaires, you must be aware of the more important problems/concerns. Following is a discussion of some of the challenges Colonial Electric Supply has run into on some recent projects.
Outdoor LED luminaires today are rated for a number of different temperature ranges, with the maximum typically running around 120°F for standard products. However, on some outdoor installations in the southern United States, especially in alcoves and unprotected areas located in direct sunlight, temperatures can easily soar past this level.
In fact, on one recent large government project, specifications called for 120°F-rated luminaires, which our firm supplied. However, following the installation, field tests revealed on-site temperatures exceeding 160°F, leading us to work with the contractor to remove, retrofit with mil-grade capacitors, and reinstall quite a few of the LED-based luminaires. What's the lesson to be learned here? Be aware that high heat and humidity levels can lower product life spans, and make sure you meet all manufacturer specifications as to where products should be installed. If in doubt, contact the manufacturers you're considering using, and request a site visit prior to purchase or installation.
Although moisture can be the enemy of any luminaire, it presents a unique problem for outdoor LED-based luminaires. Similar to the way moisture affects a cell phone or laptop, as moisture enters the housing of an LED luminaire, it can quickly short it out. In fact, it's not uncommon for service or repair work on LED luminaires to involve the recaulking of housing openings. In especially high-humidity applications, moisture creep has been found to be a considerable problem.
This occurs when the outside conditions cause condensation on the inside of the enclosure. While the enclosures may be sealed very tightly by lighting fixture standards, they are not vacuum sealed or produced like ones made for explosionproof applications, for example. The electronics do need some ventilation. Newer generation LED enclosures may have better venting and climate-controlling features that seek to prevent moisture from developing; some are even considering the use of small fans for ventilation similar to the microprocessor in a computer.
Our firm first noticed this problem on a large casino application several years ago. Why do color matching problems still exist today? Because LED chips are produced in batches and are actually kept organized in separate bins by manufacturing production runs. The bin is a manufacturer term for the storage location of a certain batch of LED chips that were all produced in the same manufacturing run on the same day. If the LEDs are supplied from the same bin, then they will have the same color characteristic.
The challenge has been to exactly reproduce the color from one batch of product to the next. On large outdoor accent lighting projects, the color differences can be very noticeable to the casual onlooker. Typically, the differences in color shading are minor. However, depending on the proximity of the application to street level and the quantity of LEDs coming from different batches, this may or may not be a big problem. Some jobs require a trial and error process in order to find the best match when applying new LEDs to an existing application. The manufacturers' answer to this is to, whenever possible, equip all luminaires with LEDs from the same manufacturing batch and bin. Unfortunately, when it's time to replace a luminaire, you're now faced with installing a non-matching unit.
To combat this problem, some manufacturers recommend using products such as a light sanding agent to dull out the newer/brighter LEDs so they match the existing units that are well into their useful life. Another solution is to ensure that extra LEDs from the original batch are dedicated to attic stock for the project. However, our firm has had success using the sanding technique as described above. Perhaps the best solution — but also the most expensive — is to use color-correcting LEDs. This type of product measures the Kelvin temperature output and corrects the whiteness or yellowness of the light to a preprogrammed level. This way, you control the color of the light, not the LED bin.
At the top of the installation challenges list is the issue of varying voltage levels. Most LEDs do not run on line voltage, so a stepped-down voltage is needed to power the device. This reduced voltage is typically supplied by remote ballasts. Contractors have been dealing with low-voltage lighting for years, so this is not the problem. What is new is that LEDs operate in a variety of low-voltage ranges, depending on the brand and application.
Unlike typical low-voltage lighting products, getting the voltage slightly wrong in an LED-based system is a bigger problem for the LED. Because LEDs are extremely sensitive to under- or over-voltage, you must calculate voltage drop carefully and correct for it. Capable transformers may have multiple taps within small differentials, and picking the wrong tap is a common problem. Because most of the traditional low-voltage products work properly when using any of a number of similar voltages, installers have sometimes improperly assumed that LED lighting will react the same way. To add to the confusion, many different wiring connector solutions exist, even within the same brand of product.
Don't take dimming an LED-based luminaire for granted either. Sometimes it works as if the source is an incandescent lamp; other times, if the voltage is too low, for example, standard dimmers do not work. Therefore, it's important to review the compatibility of the product prior to installation. There is no rule of thumb, but reputable dimming companies are well aware of this dynamically changing issue. Contractors who do not have direct experience with a particular dimming application should contact the dimming manufacturer to ensure compatibility.
Finally, installing LEDs on larger outdoor projects typically requires you to use a computer interface. Many contractors are fairly competent on the standard DMX interface that has been used for interfacing theatrical lighting with computers for years, but what was once a niche application used mainly in theatrical lighting has now become mainstream. For our firm, teaming up with theatrical specialists or system integrators has proven well worth the investment. But even then, the complexity of the project sometimes cannot be overcome. For example, our company supplied LEDs for a large airport project a few years ago. Upon a recent visit, the large color-changing LED luminaires were still not operational. Although we can't say for sure what the problem is, we are confident that the products work as designed — leaving us to suspect that the configuration has just not been completed yet.
On smaller applications, such as those that typically involve retrofitting LED product into incandescent fixtures and are often found in downlights, one of the common problems with LED indoor luminaires has been that adhesives used in fixture construction fail or are compromised, which causes them to interact with the LED source and results in light distortion or a complete failure of the product.
Contractors should be on the lookout for LED products that appear cheaply constructed or those coming from an unknown source. Because LED technology is so new, there are many low-level (typically offshore) mass producers of these types of products that sell mainly on price. As the saying goes, “You get what you pay for.” In these cases, it's a short product life cycle. Many of the more well-known brands also outsource some production to these companies and have learned the hard way the need for closely monitoring quality control. As time goes on, the more reputable companies in the lighting industry have upgraded their sourcing or taken the process in-house.
The biggest problem our firm has encountered with LED luminaires is — as a realtor would say — location, location, location. The early hype was that LEDs could be put into inaccessible locations because, it was claimed, the light source would last forever — the luminaire wouldn't even need servicing. Lately, however, the manufacturing community is backing off this claim — and for good reason. In many cases, these luminaires have not proven to be any more robust than the familiar lamp-based luminaires they're replacing.
Several large projects in the Gulf Coast region have not gone well, requiring replacing and upgrading of parts such as capacitors and housings mid project. Based on our research, no single brand is immune from trouble; several are reacting similarly to the conditions of extreme heat and humidity. Although they do perform well under shock conditions and offer lengthy life spans of more than 50,000/hr, they are electronic-based products. Therefore, when installed outdoors, they can act quite finicky, producing far less light output than expected, turning on and off intermittently, turning on at low levels when they are set to the off position, or just plain failing.
Another issue to make note of is that well-known lumen calculations are lacking when applied to LED light sources. Beam spectrum most definitely needs to be considered during the design phase of the project. In fact, it's best to double-check these calculations with a lighting designer who has real-world experience with LEDs.
Lack of standards
Because this technology is so new and rapidly evolving, there are no solid standards to reference at this time. Manufacturers and suppliers are not bound by a coordinated code of standards or even terminology. For example, broad spectrum, broad-angle spectrum, full spectrum, and wide spectrum are all used in the LED world and may or may not mean something similar. Unfortunately, users need to go directly to each manufacturer's literature to understand the specific features and abilities of the product being supplied.
The LED lighting revolution has and will continue to drastically change the lighting world. While contractors should not believe all of the hype and claims from LED manufacturers, these products provide many advantages over almost all of the more established and well-known lamp-based luminaires. Although the problems cited above relating to the newness of the technology are certainly cause for concern, the biggest disadvantage right now is still the product's high price. Based on its soaring popularity so far, it looks like the market has decided the pros outweigh the cons.
As a company with firsthand experience in working with these new products, having supplied millions of dollars of LED lighting since the technology's inception and well over $200 million in commercial lighting projects over the past decade, Colonial Major Projects would like to remind you of a common phrase — “buyer beware.” Do not make assumptions. Research existing installations, and talk to the owners and other contractors about their experiences with these products. It's probably worth paying a little extra to go with a respectable brand and supplier you're confident will be around to support the product after the sale.
Bellwoar is president of Colonial Electric Supply, headquartered in King of Prussia, Pa. He can be reached at firstname.lastname@example.org. Hammelef, executive vice president of Colonial Major Projects, can be reached at email@example.com.