Assessing Safety and Performance of LED “Grow Lights”

The use of horticultural lighting or “grow lights” has been common in the industry for years, allowing plant growth in controlled environments. These products are defined as luminaires intended to be installed in a horticultural application either above the canopy or within it. In recent years, products using light-emitting diode (LED) technology have become increasingly popular, as they offer the potential for better energy-efficiency as well as better plant growth. In fact, the global market for LED horticultural luminaires is an expanding market, on pace to grow more than 18% in the next decade, reaching $20.3 billion by 2030.¹

The growth of LED horticultural lighting products is fueled by expanding global population, urbanization and increasing disposable incomes, all of which increase the demand for food products to be produced with less space.¹ This, in turn, drives the demand for agriculture to take place in controlled environments. However, the very nature of these controlled environments means there are special considerations for ensuring the safety and performance of these products, and they cannot be tested to the same standards as general lighting. The industry is responding to these needs, and applicable standards are emerging and evolving. It is important to know what is required and what is on the horizon for this expanding market.

Safety Considerations

In August 2019, the harmonized standard ANSI/CAN/UL 8800 was published for the U.S. and Canada to support manufacturers in certifying and selling lighting products and accessories such as wire harnesses for horticultural lighting applications. ANSI/CAN/UL 8800 is the primary North American safety standard for horticultural lighting.

ANSI/CAN/UL 8800 applies to horticultural lighting installed in accordance with the U.S. National Electrical Code (ANSI/NFPA 70) and/or Part 1 of the Canadian Electrical Code. The scope and compliance requirements of this include considerations for the intended environment and use of these products. It also provides guidance on cautionary markings and instructions.

Photobiological Safety Requirements

Photobiology concerns itself with the relationship between light’s radiation and living organisms exposed to the light. It is an important consideration for these products, as many humans will be exposed to the lights as part of their work environments. As such, they must be assessed according to IEC 62471, Photobiological safety of lamps and lamp systems, and classified into an applicable risk group from the IEC standard.

The acceptable risk group classifications for grow lights when assessed to the IEC standard are: Risk Group 0 (Exempt, or no photobiological hazards); Risk Group 1 (no photobiological hazard under normal behavioral limitations); or Risk Group 2 (does not pose a hazard due to aversion response to bright light or thermal discomfort). Risk Group 3 (Hazardous even for momentary exposure) is not permitted for horticultural lighting under ANSI/CAN/UL 8800.

Elevated Ambient Requirements

It is common for horticultural luminaires to be used in elevated ambient conditions, such as those found in greenhouses. These warmer temperatures naturally result in a unique environment in which these lighting products will exist. As such, the standard requires that temperature testing be conducted at the anticipated ambient rating for the product, instead of 25°C as is typically done for an LED luminaire, hardware or system.

The standard requires that all horticultural luminaires comply with the following:

• Be subjected to the temperature test of ANSI/UL 1598 / CSA C22.2 No. 250.0;
• Be subjected to the abnormal temperature test of ANSI/CAN/UL 8800 (units with motors);
• Be marked in accordance with Table 20.1.1, Item 1.6 of ANSI/UL 1598/ CSA C22.2 No. 250.

Humidity Requirements

Similar to the high temperatures one would anticipate in a grow light setting, it is also inevitable that these products will encounter moisture and humidity, as water is a critical component of horticulture. As such, horticultural luminaires must be rated suitable for “damp” or “wet” environments in accordance with ANSI/UL 1598/CSA C22.2 No. 250.0 for fixed luminaires.

Ingress Protection Requirements

An ingress protection (IP) rating refers to the degree of protection an electronic or electrical enclosure provides against external dust, fluid or other objects that may pass through or into the product. As outlined above, it can be expected that grow lights will be exposed to water and, as such, all luminaires must be rated “damp” or “wet” and must comply with both the rain and sprinkler tests of Clause 13.4.8 of ANSI/UL 1598. This includes the following requirements:

• Based on installation type, the luminaire needs to comply with requirements of location designations in ANSI/UL 1598: LOC-3, for ceiling-mounted recessed lights; LOC-4 for wall-mounted surface lights; LOC-5 for wall-mounted recessed lights; or LOC-6 for surface and pole- or post-electric parts.
• A luminaire exposed to dust and water can be marked with an IP code of IP 54 or higher per IEC 60598-1.

Enclosure UV Exposure Requirements

An additional consideration unique to horticultural lighting is exposure to UV for polymeric enclosures or components. These take into account the unique setting and role of grow lights to ensure the materials are suitable for such use and will endure the UV exposure. ANSI/CAN/UL 8800 includes the following requirements:

Horticultural LED luminaires utilizing polymeric enclosures must comply with the requirements of ANSI/UL 1598/CSA C22.2 No. 250.0 for fixed luminaires or UL 746C/CSA C22.2 No. 0.17 for polymeric materials used in electrical devices.

Horticultural luminaires utilizing polymeric material for a water shield need must use shields made with UV-rated material.

Supply Connection Requirements

The standard also includes several provisions for supply connections. Per the requirements, horticultural luminaires are to be provided with an outlet box for fixed wiring applications, with a cord or provision to a proprietary wiring system. Use of a plug would be dependent on electrical codes, such as NFPA 70, Article 410.16, and local jurisdictions. When used, the plug must be suitably rated for the environment. Finally, considerations should be made for elevated ambient conditions, corrosion, and high humidity for these components, just as for the luminaire itself.

Performance Considerations

Safety is just one concern for horticultural luminaires. As seen with other electrical products, performance is another factor that must be considered. If a product is relative safe but performs poorly and does not function well, the product will not fill the need or be successful. While the ANSI/UL/CAN safety standard addresses one side of this coin, several industry associations are developing voluntary standards to address performance of horticultural and agricultural lighting applications.

American Society for Agricultural and Biological Engineers (ASABE)

ASABE has several performance standards that can be used when developing grow lights. The scope of these documents is as follows:

• ASABE S640 – Quantities and Units of Electromagnetic Radiation for Plants (Photosynthetic Organisms). Published in July of 2017, this standard provides definitions and descriptions of metrics used for radiation measurements for plant growth and development. A key factor to a successful grow light is ensuring it emits the right amount of the proper kind of light to aid in photosynthesis. This standard addresses the needs of plants, defining 33 electromagnetic radiation types, including ultraviolet, photosynthetic, far-red and spectral ranges.
• ASABE S642 – Recommended Methods of Measurements and Testing for LED Radiation Products for Plant Growth and Development Standard. ASABE’s second standard, published in October of 2018, provides guidance on methods for testing and measuring LED packages and arrays/modules, LED lamps, and any other LED devices used for plant growth and development. This standard specifically targets products with a spectral range between 280 and 800 nanometers (nms).
• ASABE X644 – Performance Measures of Electromagnetic Radiation Systems for Plants. This draft standard is intended to establish appropriate performance criteria of luminaires designed for horticultural applications, as well as installed systems that use such devices. The primary focus of the standard includes electromagnetic output and efficacy. It recommends minimum and advanced criteria, plant spectral response characteristics, and methodologies to compare the plant growth and energy performance between alternative devices and installed systems when applied to diverse horticultural operations.

The DesignLights Consortium® (DLC)

The DLC, which focuses on energy optimization through interconnected lighting solutions, has a vested interest in ensuring that energy efficient options like LEDs are utilized in horticultural and agricultural applications. The DLC Horticultural Lighting program is a suite of tools and resources designed to encourage and enable widespread adoption of LED technology in the horticultural lighting sector. It includes technical requirements and a listing of qualified products that meet these requirements.

The DLC program includes output characteristic requirements for reported metrics, which includes metrics for photosynthetic photon flux (PPF), far-red photon flux (PFFR), spectral quantum distribution (SQD) and photosynthetic photon intensity distribution (PPID). It also includes required minimums for photosynthetic photon efficacy (PPE) (µmol/J), photon flux maintenance, photosynthetic (PFMP), and photon flux maintenance, far-red (PFMFR). There are also requirements to have appropriate horticultural lighting safety certification by an OSHA NRTL or SCC-recognized body.

The program also includes requirements for efficacy, long-term performance, warranty, driver testing to real-world applications or In-SITU temperature measurement testing (ISTMT), electrical performance/power quality, safety, and tolerances. Supporting documentation under the program includes test reports from an accredited lab, application forms, marketing materials, specification sheets and applicable certifications.

Regardless of the standards manufacturers elect to use or programs in which they’d like to enroll, it is important to understand the requirements and build a test plan that can be used throughout the product development process. Doing so will also require knowledge of other applicable standards referenced in these requirements, from general electrical safety to requirements specific to the settings where these luminaires will be used. It will also be important to work with a knowledgeable party to conduct testing. In some cases, testing conducted by a DLC-approved lab will be required.

As the demand for efficient grow lights continues to increase and the industry looks for ways to accommodate these needs, ensuring the safety and performance of these products is essential. The industry will undoubtedly continue to evolve, introducing and modifying standards, making it necessary to keep up to date with these changes. Working with a trusted partner to stay informed, creating a test plan and conducting the necessary testing will be essential in bringing these in-demand products to market.

Source

1. “Horticulture Lighting Market to Generate $20.3 Billion by 2030,” on Account of Population Boom: P&S Intelligence. Globe News Wire. March 24, 2020. Accessed 6.10.2020