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How to Evaluate
an LED Fixture

A contractor’s checklist for choosing
the right LED fixture for the job.
 

June 27, 2017 
Author: Jeff Campbell, Head of Luminaires for LEDVANCE, maker of SYLVANIA general lighting
in the US and Canada
 
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Many electrical professionals are now familiar with the benefits of LEDs as an illumination technology. This extraordinary light source has transformed the way lighting can be used and implemented, but in some ways, it has proven the adage that “The more things change, the more they stay the same.” Choosing a quality light fixture still observes the same fundamentals as traditional luminaires, but the metrics are changing.

At a macro-level, the LED lighting market is split between specification-grade and high-volume (“white goods”) products, which is very similar to the traditional lighting market. The specification-grade side focuses on performance and innovation, while the white-goods side focuses on delivering the standard benefits of an LED luminaire - efficiency, low maintenance and long life at a competitive price. Electrical contractors and related professionals enjoy considerable influence in selecting white-goods-type LED products. 

The name of the game here is value, which represents a fine balance between performance and price. In the traditional lighting market, pursuing the lowest price may not have been the ideal solution, but it typically went unnoticed. With LED technology, that is no longer the case. The fact is, in the traditional lighting market, we could focus on price because basic metrics and standards implied a certain baseline level of value. With LED, performance cannot be taken for granted. The LED market is still in the early stages of development, with wide variations in performance and many new companies. The primary task of an LED luminaire is to provide the necessary light to the illuminated environment, and deliver on the promise and potential of the LED technology. Protecting the customer’s expectation and your reputation requires careful evaluation of products and manufacturers.

LED lighting fixtures are affected by three variables that should be on every electrical professional’s checklist: design, performance and quality.

Design

Simply put, design is about how the light fixture is built and takes into account mechanical, optical and thermal design characteristics.

Construction. This includes size, materials, finish and thermal management. The fixture must be properly designed and rated for its intended environment and carry the associated ratings and certifications. For example, many industrial and outdoor applications require a certain degree of protection against water and dust ingress, and must have an appropriate ingress protection (IP) rating.

Thermal design refers to how well the fixture removes heat buildup from the LED. The thermal design is critical to realizing the benefits of an LED-based fixture in terms of both light output and life. Be sure to ask the manufacturer about its approach to thermal design, and if they can provide the necessary third-party generated LM79 reports to confirm performance.

Fixture efficiency and distribution. Fixture efficiency refers to how much light produced by the LED source exits the fixture, and  distribution describes the light fixture’s emission pattern; where does it put light, with what intensity, and how does this meet the requirements of the application? Distribution, combined with light output, dictates how many light fixtures are needed to satisfy the owner’s lighting criteria.

Ease of installation. This involves how simple it is to install a light fixture, how much time it takes, and how prone it is to issues that can result in call-backs.  Fixture designs vary greatly, so contractors should review installation manuals and product information for any specialized tool or assembly requirements.  This is critical for proper project estimation, and reducing potential issues on the jobsite.

Performance

Performance describes what the light fixture does, which is measured using a variety of metrics.

Light output. A primary consideration in selecting a light fixture is its light output, measured in lumens. This value should be confirmed by a third-party test report, and a good resource is LightingFacts.com, which lists thousands of LED products with their light output being a key metric.

Unlike traditional sources, such as fluorescent, where lamps fail along a mortality curve and are constantly being replaced, LED products lose light output over time until the fixture should be replaced.

Lumen maintenance. The above brings us to lumen maintenance, which provides the number of burn-hours passed until the light output is a percentage of initial light output. LED products are typically evaluated to 70% lumen maintenance, or L70. This number is an average for a significant population of the fixture being evaluated.

Consistency. The LEDs should be manufactured using methods that ensure a high degree of consistency in light output between light fixtures. Severe inconsistencies could result in fixtures that differ in brightness or color, which will be objectionable to the end user.

Efficacy. Efficacy defines the amount of light output (lumens) per unit of electrical input (watt). High efficiency fixtures can maximize energy savings and improve return-on-investment calculations.  One of the primary benefits of LED technology is reduced power consumption, and efficacy is the primary indicator of that performance.

Service life. LED fixtures have multiple failure modes, including lumen depreciation over time, driver failure, LED array outages affecting light distribution, and color shift.

Lumen depreciation is a defined metric based on standardized testing.   Manufacturers must comply with these standards, and a good indicator of this compliance is the Lighting Facts label.  Any fixture without this label should be considered carefully.

Color quality. The color quality of the light output can be defined by CRI and CCT. CRI (color rendering index) indicates how well a light source renders a batch of test colors compared to an ideal reference source. A CRI of at least 80 is considered acceptable for most commercial applications.

CCT (correlated color temperature) expresses the color appearance of a light source. CCTs are described as warm (yellow/orange) like an incandescent or halogen lamp, or cool (white/blue) like a fluorescent lamp. Mixing fixtures with different CCTs can create unattractive spaces. The CCT should be matched to the space and the application, depending on the installed finishes and usage of the space.

Control performance. LED fixture controls vary widely from simple on/off and dimming, to more complex two-way communication and integrated sensor designs.  Fixture control compatibility must be consistent within the installed space.  Manufacturers should provide all applicable compatibility and programming information, including third-party sensor and dimmer compatibility, and detailed instructions for setup of integrated sensors. Complete information is critical to providing performance that satisfies end user expectations.

Quality

Quality is proof that the product will perform well and as promised over the long term.

Environmental ratings. The fixture should have all appropriate environmental testing and ratings appropriate for its intended application including IP (ingress protection) rating, operating temperature range, and FCC (Federal Communications Commission) compliance.

Safety. All LED fixtures must have UL or ETL certification to all required safety testing and ratings.

Quality certifications. Some projects, such as those receiving utility rebate funding, may require the product receive a quality certification such as ENERGY STAR, or DLC (Design Lights Consortium). These certifications indicate a given product has been independently tested and found to satisfy or exceed certain performance criteria, and qualify for utility rebate incentives.

Warranty. Warranty terms and conditions vary greatly between suppliers, and should be carefully considered.  The true value of a lighting product takes into account numerous variables, and the history, longevity and reputation of the manufacturer should factor strongly into any warranty evaluation.     

Finding true value

Electrical contractors and related professionals need products that meet design, performance and quality requirements to assure satisfied customers and trouble-free installations.   The SYLVANIA LEDVANCE portfolio of indoor and outdoor fixtures fit everyday application needs and have been designed with the needs and requests of electrical contractors in mind - high performance, energy savings, simple installation, and proven quality. 

By observing a basic but comprehensive checklist, you will ensure that you are providing a product that meets code standards, assures a trouble-free installation and provides a quality product for your customer.