June 09, 2011 | 0 Comments
Todd Fries, HellermannTyton, describes recent fire and electrical codes that affect solar photovoltaics (PV) installations, debunking some myths and describing what installers need to know to pass inspection and properly label PV systems.
Todd Fries, HellermannTyton
June 9, 2011 -- Define acceptable photovoltaic (PV) infrastructure labeling. If you can't, you're not alone: if there is one thing that that every solar PV installer, engineer and designer can agree on is that there is no universal consensus labeling. The industry is so new and the codes and regulations are so diverse that most installers are left on their own trying to pass inspection and meet National Electrical Code (NEC) and the International Fire Code (IFC) labeling requirements.
NEC and IFC standards go hand-in-hand and address key issues of PV labeling. Fire Marshalls are concerned about the safety of first responders and emergency personnel if ever they are needed on a photovoltaics install site.
NEC code section 690 outlines the basic parameters for labeling. The IFC goes a step further, defining the size of text, color and physical properties of the label. This is a start for the process of label standardization.
There is still much confusion and misunderstood information when it comes to PV labeling. The PV solar industry can expect 21GW of installations in 2011. It is not uncommon for an installer to believe that the use of etched plates is mandated by the NEC code, or that markers are mandated to last 20+ years on a solar installation. But when you cut out all the white noise, what are the real facts of PV system labeling and how should the installer address the complex and often diverse issues regarding labeling and how that relates to passing inspections by the authority having jurisdiction (AHJ)?
First, the NEC and IFC do not define a particular method of marking the infrastructure. In NEC 2008, there is a phrase that reads as follows: “The labels are required to be a durable, unalterable material permanently attached to the device. The most common type of labeling is engraved or etched plastic, which can be riveted or adhered to the device.”
The key here is that they are simply indicating that the most common type in use in 2008 was an engraved plate. In the past, many inspectors and installers have interpreted this to mean that an etched plate is mandatory if you want to pass inspection and have the marker last 20+ years. The NEC 2011 simply states that the markings shall be of sufficient durability to withstand the install environment.
But what about that 20+ year rating? There is no problem with using an engraved plate, but the installer needs to be aware that most phenolics are not UV rated for outdoor use. They can be costly and limited when it comes to meeting recent requirements. New standards are written in such a way as to allow the installer to pick any of various identification methods. For instance, the soon-to-be-released IFC 2012 says that adhesive-fastened signs may be acceptable if properly adhered, and vinyl signs should be weather-resistant. Adhesive label manufacturers, in the label converting industry, will typically certify their label materials, up to five years for outdoor durability, in direct exposure to the elements. Many fully pre-printed labels have a nine year rating, which is phenomenal in the labeling market. The typical definition of “outdoor durability” is that the labels should show little or no degradation during that time period and then slowly degrade as the years go by. Labels in shade or protected from direct exposure to sun and the elements can last two or three times as long before starting to break down.
Because labels must give emergency responders appropriate warning and guidance about the solar electric system, the IFC actually goes one step further in defining critical labels that are preventing a life-threatening hazard. One example is energized electrical lines that connect the solar modules to the inverter, as these should not be cut when venting smoke from a burning building. Cutting into a live conduit could result in a 520V jolt, so safety is a primary concern. IFC/NEC specify that electrical metallic tubing (EMT) conduit and raceways must be marked no less than every 10 feet, at every turn, above and below penetrations, and on all exposed raceways, cable trays, and other wiring methods. The labels also must be visible on the covers or enclosures of pull boxes and junction boxes and conduit bodies in which any of the available conduit openings are unused. The label (Fig. 1) is to be printed: PHOTOVOLTAIC POWER SOURCE. Further, the IFC requires that these labels have reflective properties so that they are clearly visible in a flashlight beam. The IFC specifies that the markings must be visible from a distance -- minimum text height is 3/8" using white lettering on a red background.
Finally, the IFC recommends that the marker meet UL969, an adhesive label specification, which is another added consideration for the installer when determining how best to label a system.
If we combine some of the labeling specifications against the actual end-use applications, which can vary by substrate, UV exposure, and other environmental factors, consider these options:
NEC690.4(F) specifies that the installer must clearly mark circuits that are hidden under build-up, laminate, or other membrane roofing materials that are not covered by PV modules. Typically, a metal shingle label or something permanent can be attached to tar and composite shingles (Fig. 2). The IFC would prefer to see labels that identify the main service disconnect or critical disconnects with reflective, red and white labels (Fig. 3).
All other warning and caution labels can have a heading that is at least 50% taller than the body text. The message text should be at least .12" tall (Fig. 4). If we compare this to Occupational Safety and Health Administration (OHSA) 1910.145 and the American National Standard Institute (ANSI) Z535, they specify that signs must be visible at a safe viewing distance from the hazard. They also recommend the use of safety alert symbols, where applicable.
The color red serves to satisfy both the Fire Marshall and the AHJ when approving installations. On the one hand, this might make the work of labeling more complex, but it opens the door for a variety of labeling packages pre-made for PV installers.
The new NEC2011 and IFC2012 offer new insights into the dynamics of labeling a PV installation. The updated standards open the door for appropriate use of high-quality labeling products designed against UV exposure fading and provide a permanent marking on low energy surfaces, such as powder coat paints found on many of the new breaker boxes and inverters. These updates come at an opportune time, when the market is now capable of supplying label inks and adhesives that are UV stable and adhere to various surfaces failing due to temperature or environmental changes.
Improved and targeted labeling materials should cut costs for PV installers. For example, if a high-quality, UV-stabilized, pre-printed or semi pre-printed label is used, the cost of labeling a typical installation goes from $60-70 per installation down to maybe $10-20. In addition, the installer is more likely to be truly compliant to NEC, IFC, and applicable UL, OSHA and ANSI standards.
There is one caveat: local regulations. Some communities mandate engraved plates, and in those instances the installer must comply. Yet, in most communities, there is no specific definition of marker type. This gives the installer leeway to select an appropriate labeling solution. Again, there is no right or wrong answer on marker selection, as long as the installer is meeting the requirements of the AHJ in all instances. Labeling products with specialized features, such as reflectivity, are the vanguard of the new era.
The market is still new and evolving and like any other industry, solar energy players will seek to find the best solutions at the lowest cost. The cost of failing an inspection is just as important as the cost of a marker. As the standards become more defined, additional solutions will become available to the designer, engineer and contractor.
Many changes are sure to come as the industry evolves and labeling will have to grow with those changes to become a standard that everyone can define and implement now and in the future.
Todd Fries received his BA from the University of Whitewater Wisconsin and is the marketing manager of Identification Systems at HellermannTyton, 7930 N. Faulkner Rd., Milwaukee, WI 53224 USA; 1-800-537-1512; TFRIES@htamericas.com.
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