Circuit Disconnects Switches and Enclosures. Enclosures shall be surface mounted type, unless otherwise noted, and of NEMA type 3R, waterproof. Disconnect Switches shall be DC or AC rated, as appropriate, with appropriate ampere ratings as required. They shall be UL listed and of NEMA type 3R, waterproof, meet proper AIC requirements, be correctly rated for DC or AC operation, as appropriate, and be “load-break” capable. Disconnects and enclosures must be properly supported and braced to Seismic zone requirements, where required. When used for disconnecting, disconnects for branch circuit protection shall be located per code. Switchgear must be accessible. The location of the disconnect switch may be acceptable as long as it is accessible 24/7 and approved by the local electric utility.
Circuit Disconnects Switches and Enclosures. Enclosures shall be surface mounted type, unless otherwise noted, and of NEMA type 3R, waterproof. Disconnect Switches shall be heavy duty, DC or AC rated, as appropriate, with appropriate ampere ratings as required. They shall be UL listed and of NEMA type 3R, waterproof, meet proper AIC requirements, be correctly rated for DC or AC operation, as appropriate, and be “load-break” capable. Disconnects and enclosures must be properly supported and braced to Seismic zone requirements, where required. When used for disconnecting, disconnects for branch circuit protection shall be located as near as is practical to the supply end of the conductors being protected. Switchgear must be accessible. The location of the disconnect switch may be acceptable as long as it is accessible 24/7 and approved by PG&E. Fuses: All low voltage fuses for disconnects must be current limiting UL class J, RK1, or RK5 and of the appropriate voltage, delay or non delay characteristic, and current rating to provide both complete short circuit and overload protection per NEC sections regarding component protection. Fuses in the combiner boxes protecting PV string branch circuits must be UL class CC midget type, be in “shock-safe” type fuse holders “touch safe”, providing load break disconnect capabilities when changing fuses. Midget fuses and fuse holders used in these circuits must be fully DC rated and adequate DC short circuits withstand capability must be provided for all power situations including “back-fed” conditions. All fuses and other protective devices and holders must be engineered to safely protect system components under “worst case” expected field conditions including temperature extremes. PV panel strings must be individually protected from short circuit conditions that may originate within the panels themselves.
