IEC 60898-1 vs IEC 60947-2: MCB Standards Compared
What is the difference between IEC 60898-1 and IEC 60947-2 for MCBs? IEC 60898-1 covers circuit breakers for household and similar installations, operated by ordinary persons, with breaking capacity marked as Icn in amps (3000, 6000, 10000). IEC 60947-2 covers industrial circuit breakers for skilled operation, rated with Icu and Ics in kA, and it opens the door to K and Z curves and higher breaking-capacity tiers. The choice affects which curves are available, how the nameplate reads, and whether the breaker satisfies a panel-builder's type-test declaration or only a domestic installation certificate. This article covers scope and audience, the Icn vs Icu/Ics marking split, curve availability by standard, dual marking, a side-by-side table, and what it means for approvals and selectivity.
One Component, Two Standards, Two Audiences
A miniature circuit breaker looks identical whether it ships under IEC 60898-1 or IEC 60947-2. Same DIN-rail clip, same 18 mm module width, same thermal-magnetic trip block inside. What differs is who the standard assumes is operating it and how the breaking capacity gets tested and declared. IEC 60898-1 is written for the general public — a homeowner resetting a tripped breaker without training. IEC 60947-2 assumes a qualified electrician or panel builder who understands duty cycles, discrimination, and fault levels.
That assumption changes the test regime. IEC 60898-1 requires a single breaking capacity value, Icn, and a fixed sequence of operations at that current. IEC 60947-2 requires two values — Icu and Ics — because industrial breakers are expected to survive a fault and remain usable afterward, not just clear it once.
IEC 60898-1: Breakers for Ordinary Persons
Under IEC 60898-1, breaking capacity is stated as Icn — rated short-circuit capacity — in amps, and the common commercial values are 3000 A (3 kA), 4500 A (4.5 kA), 6000 A (6 kA), and 10000 A (10 kA). 6 kA is the standard figure for most commercial and residential boards; 10 kA shows up close to the transformer, where prospective fault current is higher. Curves permitted are B, C, and D. K and Z are not part of this standard's scope.
The test sequence for Icn is O-t-CO-t-CO (open, time delay, close-open, time delay, close-open), and after the sequence the breaker must still trip correctly on overload — it does not have to demonstrate a second full-current interruption at a reduced value. That single-tier test is adequate for a consumer unit that will see one fault in its service life, get inspected, and likely get replaced rather than reused after a serious event.
IEC 60947-2: Breakers for Skilled Operation
IEC 60947-2 assumes the person resetting the breaker understands what tripped it. The breaking capacity is split into Icu (rated ultimate short-circuit breaking capacity) and Ics (rated service short-circuit breaking capacity), both in kA. Icu is the current the breaker can interrupt once, after which it may not be usable again without inspection. Ics is the current it can interrupt and remain serviceable at rated current afterward — this is the number that matters for a breaker expected to stay in service after a fault, not get swapped out.
Ics is expressed as a percentage of Icu, and the manufacturer declares which tier applies to a given reference.
Formula: Service breaking capacity — Source: IEC 60947-2, Icu/Ics rating clause
Ics = k × Icu
| Symbol | Description | Unit |
|---|---|---|
| Icu | Rated ultimate short-circuit breaking capacity | kA |
| Ics | Rated service short-circuit breaking capacity | kA |
| k | Declared percentage factor (typically 25%, 50%, 75% or 100% of Icu) | % |
A breaker declared Icu 25 kA / Ics 100% will still interrupt at full capacity and go back into service. A breaker declared Icu 25 kA / Ics 50% clears the same fault once, but the manufacturer only warrants it for continued service at half that current afterward. What we see in the field: engineers reading only the Icu figure on a datasheet and assuming it is also the service rating — worth checking the Ics percentage before it goes into a selectivity study.
Same Curve Letter, Different Rulebook: B, C, D vs K, Z
B (3-5x In), C (5-10x In), and D (10-20x In) exist under both standards and cover lighting/resistive loads, general mixed loads, and high-inrush loads such as transformers and motors respectively. K (8-12x In) and Z (2-3x In) are IEC 60947-2 curves — a tighter magnetic trip band aimed at industrial motor and inductive circuits (K) or sensitive electronic and semiconductor protection (Z). A supplier catalog listing K or Z curve options is signaling IEC 60947-2 scope, even if the same physical range also carries an IEC 60898-1 rating for its B/C/D variants.
Reading a Dual-Marked Nameplate
Most European-brand MCBs — Schneider Acti9 iC60, ABB S200, Siemens 5SY — carry both standard numbers on the same nameplate. The breaker is a single physical device tested and declared against both test regimes, so it is compliant for a household board and legitimate as a component in an industrial panel's fault-current documentation. Dual marking usually shows as "IEC 60898-1 / IEC 60947-2" printed next to the Icn value, sometimes with a supplementary Icu/Ics figure alongside it.
Not every MCB is dual-marked. Economy lines built to a price point often carry only the 60898-1 number, because the manufacturer never ran the additional Ics service-duty tests. That is not a defect — it reflects the market the range was designed for.
IEC 60898-1 vs IEC 60947-2 at a Glance
| Criteria | IEC 60898-1 | IEC 60947-2 |
|---|---|---|
| Intended operator | Ordinary, unskilled persons | Skilled or instructed persons |
| Typical setting | Household, similar final circuits | Industrial panels, distribution boards |
| Breaking capacity marking | Icn (amps): 3000/4500/6000/10000 | Icu and Ics (kA), Ics as % of Icu |
| Test sequence for rated capacity | O-t-CO-t-CO, single tier | Icu once, Ics at declared % for continued service |
| Curves available | B, C, D | B, C, D, K, Z |
| Typical breaking capacity range | 3-10 kA | 15-25 kA and higher |
| Documentation weight in a fault-current study | Limited — Icn only | Full — Icu and Ics both usable |
Why the Standard Matters for Approvals and Selectivity
An inspector signing off a domestic board checks against IEC 60898-1 requirements — Icn adequate for the prospective fault current at that point, curve matched to the load. A panel builder submitting a type-tested assembly for industrial use needs IEC 60947-2 data because the assembly's short-circuit withstand rating is built from the declared Icu and Ics of every device in the fault path, not just the final Icn figure.
Selectivity studies compound this. Coordinating an upstream breaker with a downstream MCB requires knowing both devices' let-through energy and interruption behavior at the fault level in question — an Icu/Ics pair gives that; a bare Icn figure does not tell the study whether the breaker stays serviceable after the event it is being coordinated around. Specifying against the wrong standard for the application either under-documents an industrial panel or over-specifies (and overpays for) a domestic circuit.
This depends on the panel's end use, not just its physical location. A distribution board in a factory, maintained by qualified staff, sits in IEC 60947-2 territory even if it superficially resembles a household consumer unit.
Frequently Asked Questions
Can an MCB be certified to both IEC 60898-1 and IEC 60947-2 at the same time?
Yes. Many commercial MCB ranges, including Schneider Acti9 iC60, ABB S200, and Siemens 5SY, are dual-marked on one nameplate. The device is tested against both regimes and is valid for household and industrial documentation without needing a separate SKU.
Is Icu the same thing as Icn?
No. Icn (IEC 60898-1) is a single rated breaking capacity value in amps. Icu (IEC 60947-2) is the ultimate breaking capacity in kA, paired with Ics, the service breaking capacity. A breaker's Icu and Icn figures are often numerically close, but they come from different test sequences and different standards.
Why do only some MCBs offer K and Z curves?
K and Z curves are defined in IEC 60947-2, not IEC 60898-1. A manufacturer only offers them on ranges built and tested to the industrial standard, typically higher-tier lines such as ABB S200P or Schneider's industrial-rated Acti9 references.
Does IEC 60947-2 always mean a higher breaking capacity than IEC 60898-1?
Usually, but not strictly by definition. IEC 60947-2 ranges commonly reach 15-25 kA and higher because they target industrial fault levels, while IEC 60898-1 caps out around 10 kA in practice. The standard itself sets the test method, not a minimum kA floor — the higher figures follow from what industrial applications require.
Which standard applies to an MCB feeding a solar inverter or EV charger in a commercial installation?
If the circuit is maintained by qualified personnel and forms part of a documented industrial or commercial distribution system, specify against IEC 60947-2 with a declared Ics, not just an Icn figure. A residential EV charger circuit on a domestic consumer unit stays within IEC 60898-1 scope.
Do I need to re-check breaking capacity if I swap an IEC 60898-1 breaker for a dual-marked one?
Confirm the Icu/Ics pair meets or exceeds the prospective fault current at that point in the installation, and check curve compatibility with the existing selectivity study. A dual-marked replacement is a superset in test coverage, not automatically a match in trip curve or breaking capacity tier.
Conclusion
IEC 60898-1 and IEC 60947-2 test the same category of device against different operator assumptions and different duty expectations. Icn in amps versus Icu/Ics in kA is the marking to check first; curve letter (B/C/D common to both, K/Z exclusive to 60947-2) is the second check. For a household board, an Icn-rated MCB with a matched curve is sufficient. For an industrial panel or a selectivity study, confirm the breaker carries IEC 60947-2 data with a declared Ics — reading only the Icu figure and assuming it doubles as the service rating is the most common misstep. Start any spec with the miniature circuit breakers collection, cross-check curve selection against MCB tripping curves B, C, D, K and Z explained, size breaking capacity using MCB breaking capacity 3kA, 6kA and 10kA explained, and for the full selection process see the MCB engineering guide.
