This installation tip was provided by Sarah Parsons, Wiley product manager for Burndy
One underrated conversation when discussing PV system safety is wire management. Proper wire management is vital to the health of the PV system. Damaged wire insulation can lead to ground-faults, system downtime and fire. With no real industry standard for wire management, it’s difficult to police subpar installation practices and products. PV systems are installed in various environments, conditions and by different processes, so having accurate information to create a solid wire management strategy is essential.
There are countless scenarios that can lead to damaged wires. The most common issues arise from rodent damage. Critters such as squirrels love to munch on PV cable insulation. This unlucky snack choice can lead to a shutdown of the PV system or even a fire. Rough abrasive surfaces such as roof shingles can cause just as much damage. The key to eliminating these situations is as simple as securing wires neatly tucked away so rodents and other creatures do not have free access to them. Even though there is no direct reference to solar PV wiring, the NEC does call for electrical installations to have a clean, clear aesthetic (see NEC 110.12).
PV wires are not unbreakable and do have limitations when it comes to elasticity. Not observing the specified bending radius of cables can cause internal damage to the fragile copper/aluminum strands within. Not securing the wires in proper intervals puts excessive stress on connection points, junction box and connectors (see NEC 690.31 C2). Additionally, the improper tightening (overtightening) of cable ties puts pressure on PV wires, leading to cutting of the wires’ protective insulation.
Installers need to ensure they are using appropriate and listed solutions. Using generically rated or unlisted cable ties and clips can reduce the longevity of the installation. Using generically rated materials (e.g. nylon or non-300 series stainless steel solutions) that are not UV or corrosion resistant can cause breakdown over a short period of time. Listed solutions are required by the NEC (see NEC 690.31 A). Wire management solutions should be listed to UL standards.