Supply-side (line-side tap) solar and battery connections

What the code requires

Section 705.11, titled Source Connections to a Service in 2023, covers connecting a power source such as solar or batteries ahead of the main service disconnect. It allows three methods: a new service under 230.2(A), a connection on the supply side of the service disconnect under 230.82(6), or an additional set of service-entrance conductors under 230.40 Exception No. 5.

The conductors from the connection point to the power source's service disconnect must have an ampacity at least equal to the sum of the sources' maximum circuit current under 705.28(A). The minimum size is 6 AWG for copper, or 4 AWG for aluminum and copper-clad aluminum.

Splices and taps must follow 230.33 or 230.46, without overfilling the enclosure. Changes to existing equipment must follow the manufacturer's instructions or be field evaluated and field labeled. At a meter socket the utility controls, only connections the utility approves are allowed.

The source needs a disconnect for all ungrounded conductors under Article 230 Parts VI and VII, bonding under Article 250, and overcurrent protection under Article 230 Part VII. The rating of that overcurrent device decides whether ground-fault protection of equipment under 230.95 is required.

On the job

• Expect your inspector to check the minimum conductor size: 6 AWG copper or 4 AWG aluminum.
• Changes to existing equipment to make the connection must follow the manufacturer's instructions, or the modified equipment must be field evaluated and field labeled.
• Get the utility's approval before any connection is made at the meter socket.

What changed in 2023

The 2023 NEC renamed and heavily reorganized 705.11, clarified its conductor sizing, connection and bonding rules, and removed the 2020 tap-length limits of 10 ft in dwelling units, 16.5 ft in other occupancies and 71 ft with cable limiters; the source disconnect and its overcurrent protection now follow the service rules in Article 230.

Related sections

• NEC 705.12: The 120% rule for solar and battery breakers
• NEC 705.20: Disconnects for solar and other power sources
• NEC 705.28
• NEC 230.46
• NEC 230.82
• NEC 230.95: Ground-fault protection on large commercial services

Where this comes from

• NFPA: 2026 NEC (A2025) CMP-4 First Draft public input report, reprinting 2023 text
• Mike Holt (EC&M): NEC Requirements for Interconnected Power Sources, Sep 16 2024
• Electrical Contractor: Concluding the 2023 Code Review (M. Earley), Sep 11 2023
• Utah CE course outline: 2023 NEC Article 705 (Ewing-Foley)
• Read the official NEC free at NFPA