Not all showers are worth singing about!
By Jerry Plank.
The classic song “Singin’ in the Rain” recorded by Gene Kelly in the ʼ50s for the romantic musical of the same name had the performer happily skipping through the drops—but not all rain showers end up on such a happy note.
Luminaires used in outdoor locations to illuminate architectural features of structures or objects, for pedestrian wayfinding or to protect users in life safety applications issues, can fail due to water infiltration in the housing. Here we’ll discuss some of the pitfalls when installing, using or specifying luminaires for wet locations.
Terms. The number one culprit of why outdoor products fail to exclude moisture in the field is the capricious terminology that many of us are guilty of using. How many times have you heard the terms “weather tight,” “weather proof,” or outdated or misused terms such as “enclosed and gasketed,” “rain tight,” “NEMA rated,” “marine rated” or “IP rated” applied tooutdoor-rated luminaires? Simply put, the correct terminology is “suitable for wet loc
ations” which should be stated on the product. Stay away from misleading or suspicious use of terms.
Communication. All projects require close communication between the specifier, lighting manufacturer and electrical contractor, but that quasipartnership becomes even more critical on wet-location products. When installing a wetlocation luminaire, the location and orientation, as well as the assembly become even more critical. All project players must know where and how the luminaire will be mounted. Should it be mounted in an area that will flood due to the terrain, or by a soffit on a roof line that will see a concentrated flow of water, how will the excess water be diverted away from live parts? Close the loop on communication and stay engaged in the process as the project moves forward to ward off problems before a failure occurs and always be available to receive criticisms from the field.
Product Familiarity. Don’t assume that the installing electrician will know exactly how to wire, assemble or mount the exterior luminaire. Unfortunately, most lighting projects are interior applications, which means that electricians have less product familiarity with exterior luminaires. Make sure the manufacturer includes clear and concise instructions with the product.
Testing. We all assume that lighting products used in wet locations, which are listed for safety by an NRTL, will be tested to the appropriate and applicable ANSI safety standard. Accordingly, the NRTL willinclude rain and/or sprinkler tests or immersion tests depending on the products orientation during use. But not all wet-location products are tested by the NRTL’s as the safety standards allow the NRTL engineer to waive testing when it is readily apparent by the design of the luminaire that no water will enter the enclosure. However, unforeseen field conditions can, and often do exist, resulting in a leaking luminaire or wiring, which means becoming saturated or filled with water—acondition which will not be discovered if no tests were deemed necessary. Always request a copy of the tests performed by the NRTL for your records of any luminaire used.
IP-Rating Confusion. A common misconception is automatically assuming that a luminairethat has an IP rating in a project in the U.S. is appropriate. The IP rating of luminaires is a term used by the IEC (International Electrotechnical Commission), in which the first digit describes the intrusion protection, and the second digit describes the moisture protection against harmful ingress of water. The NFPA electrical code and ANSI/UL safety standards do not allow the IP rating in lieu of wet-location markings such that a municipal inspector can accept an IP-rated luminaire at this time. Further, an important caveat is that NRTL wet-location testing requires the luminaire to be energized for at least 30 minutes before a rain, sprinkler or immersion test is conducted, whereas the IP test protocol does not. This means the thermal shock is not conducted on IP-rated luminaires such that the ANSI/UL test is much more difficult to pass and less likely to fail in the field. Bottom line is that an IP-rated luminaire will require further testing to receive the NRTL wet-location marking.
Corrosion Protection. All NRTL-listed luminaires for wet locations shall have all ferrous critical parts protected from corrosion. It should be noted that decorative parts do not require corrosion protection and may be subject to atmospheric degradation. Verification will ensure that the painted metal parts can withstand the climatic conditions of the site where installed. Especially where salts or other corrosive road materials are used for deicing.
UV Protection. Thermoplastic and Thermoset materials that support or enclose live parts or act as a rain shield shall be of a material that is suitable for the application which includes an ultraviolet-inhibitor coating or additive, or be tested for degradation. Don’t assume that all polymeric parts have the same UV protection.
While it would be impossible to cover all potential pitfalls of exterior products, the items noted above should be followed as best as possible to reduce field failures. Beware of fancy terms that are not covered by the NFPA codes or ANSI/UL safety standards.