Friends:
Recently it was posited here that metallic scrims or wire guarding is required to be bonded. This is not technically correct. Section 250.4(A)(4) states bonding is required for …*non–current-carrying electrically* *conductive materials that are likely to become energized…* If it can be demonstrated that the PV wiring is not likely to ever come into contact with non-current carrying conductive parts, then bonding of those parts is not required. This link <https://millersolar.com/MillerSolar/practices/PV_wiring/Wire_shielding/Wire_shielding_recent.html> shows photos of a ground mount system I finished a few days ago. Note in the lower part of this page the superior wire management capabilities of the Snap-N-Rack 200 series channel allows the PV wire to be contained so that there is no likelihood of the conductors ever touching the mesh. Therefore there is no requirement for bonding. Note also that I did elect to bond. This is because of my general approach to do everything possible to provide the most bullet-proof product possible. It is actually quite easy to bond this type of mesh so there is no reason not to. Here is where this concept is more applicable: metal perimeter scrim. Metal scrim around the perimeter of arrays is not nearly as easy to bond. Metal scrim on the circumference of an array is located even further from the PV wiring than any mesh under panels on a ground mount. Therefore for perimeter scrim, the likelihood of PV wires touching the scrim is even more remote. This is an application where opting not to bond may save a lot of unnecessary time and materials. I think it is important that assumptions be checked for accuracy. I do not want industry wide assumptions to get accepted as gospel and require unnecessary work. This is all assuming the obvious that the elements that are in contact with the PV wire are bonded—the module frames and the mounting rail. William Miller Solar 17395 Oak Road, Atascadero, CA 93422 805-438-5600 www.millersolar.com CA Lic. 773985
_______________________________________________ List sponsored by Redwood Alliance List Address: [email protected] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org There are two list archives for searching. When one doesn't work, try the other: https://www.mail-archive.com/[email protected]/ http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out or update participant bios: http://www.members.re-wrenches.org
