IEC 60364-5-51 is part of the IEC 60364 series covering electrical installations of buildings. Part 5-51 specifies requirements for selection and erection of wiring systems and associated equipment to ensure safety from electric shock, fire and other hazards, and to enable proper operation and maintenance.
One of the most vital sections of IEC 60364-5-551 deals with preventing back-feeding. This ensures that when the generator is running, it does not feed electricity back into the utility grid. Back-feeding poses a lethal risk to utility workers repairing the grid during an outage.
The standard specifies requirements for: iec 60364 part 551 pdf
With the rise of solar and battery storage, this clause has become the most frequently referenced section. Requirements for a generator (including inverter-based sources) operating in parallel with the low-voltage grid:
For inverter-based generators (PV, battery), the standard explicitly states that the inverter’s protection functions (e.g., over/under voltage, over/under frequency) must be approved for the intended application. IEC 60364-5-51 is part of the IEC 60364
Generators have different fault current characteristics compared to the grid (lower short-circuit current, slower response). Clause 551 requires that protective devices (circuit-breakers, fuses) be coordinated with the generator’s capability to clear faults safely.
This is where Part 551 interacts with IEC 60364-4-41. For a generator operating in island mode (grid absent): For parallel operation with the grid:
For parallel operation with the grid:
Unofficial scans often have illegible wiring diagrams, missing annexes, or garbled tables. The official PDF is vector-based, searchable, and contains high-resolution figures.