NEC Article 690 — Solar PV: Rapid Shutdown, Conductor Sizing, and DC Disconnect Requirements

NEC Article 690 covers solar photovoltaic systems — the install rules upstream of the inverter (DC side) and through the AC interconnection. Pairs with NEC 705 (interconnection rules — see our 705.11(D) guide).

Rapid shutdown required (690.12): PV systems on or above buildings need rapid shutdown. The system must reduce voltage in the array and conductors leaving the array to:

• 30 V or less within 30 seconds of initiation, AND
• The voltage of conductors more than 1 ft from the array boundary must be reduced to 30 V within 30 seconds

Implementation: module-level rapid shutdown via microinverters (Enphase IQ8) or DC optimizers (SolarEdge, Tigo) is the modern default. String inverters with array-level shutdown via a separate disconnect at the array also satisfy 690.12 but are less common in NJ residential now.

PV system conductor sizing (690.8): PV source-circuit and PV output-circuit conductors are sized at:

• 125% of the maximum PV system current, OR
• Continuous duty (125%) of the inverter's max output current

For a 7.6 kW DC array with Enphase IQ8+ microinverters at 240V output: 7600/240 × 1.25 ≈ 40 A continuous. Branch circuit at 50 A breaker, 8 AWG CU minimum.

DC disconnect (690.13): every PV system needs a means to disconnect all DC ungrounded conductors. Located within sight of the inverter or lockable in the OPEN position. Required to be readily accessible for first responders.

AC disconnect (690.15): the PV system must have an AC disconnect at the AC interconnection. Lockable in the OPEN position and accessible to the utility. NJ requires it visible from the meter or within 10 ft.

Grounding (690.41 / 250): PV system DC grounding requirements were significantly simplified in the 2017 NEC. Most modern microinverter / optimizer systems are inherently grounded through the inverter. Still need an EGC running with the AC output back to the panel.

Working-space rules (110.26) apply to the AC disconnect and to the inverter — 36 inches of front clearance, 30 inches wide, 6.5 ft tall.

For solar one-line diagrams, the free Malfettone SLD Builder at /tools/single-line-diagram has a "Solar PV with line-side tap" template with the array, microinverter callout, AC disconnect with padlock indicator, and supply-side tap junction dots — ready for permit submission.

Net-metering interconnection in NJ: PSE&G and JCPL both run net-metering programs. Interconnection applications go through the utility and require this AC disconnect to be utility-accessible.