Page 32 - North American Clean Energy May June 2018 Issue

solar power
Wire management gone bad. An unidentified supplier’s UV rated cable ties, passed through a module hole, failed and significant rework was needed.
Avoid Wire Management Disasters in Three Easy Steps
by Nick Korth
Just like the weather, poor wire management application
and lack of strategy can be catastrophic. Unlike storms and natural disasters, however, wire management failure on solar installations is not only predictable, but also easily preventable.
If you want to reduce risk and added costs, consider the following three-step process:
e rst step is education. NEC 2017 prescribes a number of requirements dictating proper wire management – unfortunately, they tend to be open to interpretation.
According to NEC 110.12, “Electrical equipment shall be installed in a neat and workmanlike manner.” NEC 338.24 refers to “insu cient support of conductors and stress on junction box and plug connections.”
ese codes provide a baseline for evaluation and inspection, but they don’t guarantee a long-lasting installation. Seeking out best practices, and adopting quality assurance programs, will go a long way to ensure that installers learn and practice proven installation procedures.
For example, one site actually had a plastic-coated metal cable tie routed through a module hole. e tie was so tight that, due to wind and thermos- cycling, it had sliced through the wire jacket and caused a fault. is is
a pro t killer; any time you have to repair a serious fault, you drastically reduce your pro t margins.
Another example was damage to a cable jacket because of poor application of metal clips. It’s not uncommon to see workers pounding on poorly designed, cheap metal clips, with the back of a side cutter or screwdriver. Not only does this distort the actual clip, which a ects performance, it can cause damage to the module itself. e solution is to use better metal clips that are designed to go on easily, and hold incredibly well.
e second step in having a good wire management plan is specifying the correct materials, and having the correct product for the application. Plastic products often get a bad reputation in the solar industry, and are frequently seen as a poor alternative to metal. But, like all products, quality is often relative; you get what you pay for. Not all plastic wire management products are created equal. Plastic cable ties get a bad rap. Like everything else on the market, there are varying levels of quality; don’t let the reputation of inferior plastic products scare you away from seeking out and using a stronger, well-made, and lasting plastic cable tie.
One particular site happened to be in a desert environment, but had cheap, “UV rated” cable ties looped through solar module mounting holes. After three replacements in four years, the owner of this single axis tracker installation decided enough was enough; he speci ed and was able to nd a product to match the hazards of constant heat, thermo-cycling, wind, and sun.
But think about this: four laborers for ve days, at $20 per hour, adds up to $3,200 a year. Over the course of ve years, a site owner could spend $16,000 on labor for replacing cheap cable ties alone, signi cantly adding to the operations costs. at’s in addition to the multiple faults and connector failures, and the added risk of junction box failure due to strain on the lead wires.
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