National Electrical Code Tips: Article 690 -- Solar Photovoltaic Systems, Part
Part IV of Article 690 provides the requirements for wiring methods and materials. Nearly all of Part IV is about wiring methods. 690.31 has that heading, 690.31 is about component interconnections, and 690.34 is about access to boxes. 690.33 provides about a quarter page addressing mating connectors, the only "materials" covered by Part IV.
- You can use any wiring method in the NEC and any wiring systems and fittings specifically listed for PV systems [690.31(A)].
- PV system dc circuits and Class 1 remote control, signaling, and power-limited circuits of a PV system can occupy the same equipment wiring enclosure, cable, or raceway [690.31(B)].
- PV system dc cirucits shall not occupy the same equipment wiring enclosure, cable, or raceway as other non-PV systems, or inverter output circuits unless separated by a barrier or partition [690.31(B)]. The NEC does not explain the difference between a barrier and a partition, but since a partition is a type of barrier the question is moot. Excess verbiage (rather than clear and concise language) has long plagued the NEC. Overall, this problem is not as bad as it used to be; the CMPs have steadily been working on it.
- Identification is a really big deal with this revision. You must identify PV system conductors at all termination, connection, and splice points. The particulars are explained at length in 690.31(B)(1).
- What if you have more than one PV system and the conductors of those different systems occupy the same junction box or raceway? If the box or raceway has a removable cover, then you must group the conductors for each system using cable ties or similar means at least once every 6 feet [690.31(B)(2)].
- Can you put single-conductor PV cable in cable trays installed outdoors? Yes, if the cables are supported at intervals of 12 inches or less and secured at intervals of 4.5 feet or less [690.31(C)(2)].
- If your PV system dc circuits are inside a building and exceed 30V or 8A, they must be contained in metal raceways, Type MC metal-clad cable that complies with 250.118(10), or in metal enclosures [690.31(D)].
- Solidly grounded bipolar PV systems must be clearly marked with a permanent, warning legible notice indicating that the disconnection of the grounded conductor(s) may result in overvoltage on the equipment [690.31(E)].
- You can use concealed fittings and connectors for on-site interconnection of modules or other array components [690.32].
- Mating connectors shall be polarized and have a configuration that isn't interchangeable with receptacles in other electrical systems on the premises [690.33(A)]