Interconnected Power Sources (Article 705) and Energy Storage Systems (Article 706): the 120 Percent Rule, Source Disconnects, Backfed Breakers and ESS Disconnects
Lessons 10-01 (PV) and 10-02 (EV) cover the sources and the chargers; this lesson covers how a PV inverter, a battery or a generator connects to the premises wiring in parallel with the utility — Article 705 — and the rules for the energy storage system itself — Article 706. The Master form's Renewable Energy items lean on the 705.12 busbar rules and the 705.28/705.30 sizing chain. Written from the 2026 text.
NFPA 70 National Electrical Code, 2026 edition · Reviewed 2026-09-19
Lessons 10-01 (PV) and 10-02 (EV) cover the sources and the chargers; this lesson covers how a PV inverter, a battery or a generator connects to the premises wiring in parallel with the utility — Article 705 — and the rules for the energy storage system itself — Article 706. The Master form's Renewable Energy items lean on the 705.12 busbar rules and the 705.28/705.30 sizing chain. Written from the 2026 text.
1. The basics — 705.2 to 705.10
- Listing (705.2): interconnection and interactive equipment is listed for the interactive function or evaluated with a field label (UL 1741: stand-alone, interactive, multimode).
- Parallel operation (705.5): compatible voltage, wave shape and frequency; synchronous generators need synchronizing equipment. 705.8: installation only by qualified persons.
- Identification (705.10): a permanent plaque, label or directory at each service equipment location (or an approved readily visible location) that (1) gives the location of every power-source disconnecting means for the building (colocated sources may be identified as a group), (2) lists the emergency telephone numbers of off-site entities servicing the sources, and (3) reads "CAUTION: MULTIPLE SOURCES OF POWER".
This is where the public part ends.
The rest of this lesson, its quiz, all 3 lessons in the module and every mock exam open with the 7-day pass for $9. If you stay, it comes off lifetime.