IEC 60898 vs IEC 60947: Circuit Breaker Standards

Why Circuit Breaker Standards Matter for Procurement

When you specify or purchase circuit breakers, the IEC standard number on the device nameplate determines exactly what has been tested, how the ratings were measured, and where the device is intended to be installed. Confusing IEC 60898 with IEC 60947 — or not specifying which one you require — leads to mismatched ratings, failed inspections, and potentially unsafe installations.

This guide explains both standards in plain engineering language, so you can specify correctly whether you are buying MCBs for a housing project or MCCBs for an industrial plant. For a product-level comparison of MCBs vs MCCBs, see our MCB vs MCCB comparison guide.

IEC 60898: The MCB Standard for Residential Installations

IEC 60898-1 (full title: "Electrical accessories — Circuit-breakers for overcurrent protection for household and similar installations") was designed with a specific philosophy: the device must be safe for use by people with no electrical training. A homeowner should be able to reset a tripped MCB by simply flipping the handle back to the ON position.

This philosophy shapes every aspect of the standard:

Scope and application

• Covers MCBs rated up to 125 A and 440 V AC
• Intended for installations where fault currents do not exceed 25 kA (though most devices are rated 6-10 kA)
• Devices must be operated by "uninstructed persons" — no tools or knowledge required for normal use
• Environmental conditions: indoor, controlled temperature, altitude ≤2,000 m

Trip curve definitions (Annex B)

IEC 60898 defines three instantaneous tripping ranges that are fixed at the factory — the installer cannot adjust them:

An MCB labeled "C16" means it has a C-curve trip characteristic at 16 A rated current. The magnetic trip will activate between 80 A (5x16) and 160 A (10x16). Below 80 A, only the thermal (overload) element provides protection.

Breaking capacity: Icn

IEC 60898 uses a single breaking capacity value: Icn (rated short-circuit capacity). This is tested under specific conditions:

• Test voltage: 1.05x rated voltage
• Power factor: 0.45 for Icn ≤6 kA; 0.3 for Icn 6-10 kA; 0.25 for Icn >10 kA
• Test sequence: O-t-CO (open, rest, close-open) — two breaking operations total
• After the Icn test, the MCB must still carry rated current, but some degradation in trip characteristics is permitted

Standard Icn values per IEC 60898: 1.5 kA, 3 kA, 4.5 kA, 6 kA, 10 kA, 15 kA, 20 kA, 25 kA. In practice, the vast majority of MCBs sold globally are 6 kA or 10 kA.

IEC 60947-2: The Industrial Circuit Breaker Standard

IEC 60947-2 (full title: "Low-voltage switchgear and controlgear — Part 2: Circuit-breakers") is a far broader and more demanding standard. It covers every type of low-voltage circuit breaker: MCBs, MCCBs, ACBs, and specialty devices like motor protection circuit breakers.

Scope and application

• Covers circuit breakers at any current rating (from 0.5 A to 6,300 A+)
• Rated voltages up to 1,000 V AC / 1,500 V DC
• Intended for use by "instructed or skilled persons" — qualified electricians and engineers
• Industrial, commercial, and infrastructure installations
• More rigorous environmental testing requirements

Breaking capacity: Icu and Ics

IEC 60947-2 requires two breaking capacity values — this is the most important difference from IEC 60898:

• Icu (Ultimate short-circuit breaking capacity): The maximum fault current the breaker can interrupt. After the Icu test, the breaker need not be serviceable — it may have to be replaced.
• Ics (Service short-circuit breaking capacity): The fault current the breaker can interrupt and then continue normal operation. After the Ics test sequence (O-t-CO-t-CO — three breaking operations), the breaker must still meet all performance requirements.

IEC 60947-2 requires Ics to be at least 25% of Icu. Common Ics/Icu ratios on quality MCCBs are 50%, 75%, or 100%. A breaker with Ics = 100% x Icu is the highest quality — it can interrupt its maximum rated fault and remain fully operational.

The testing power factor for IEC 60947-2 is also more severe than IEC 60898:

A lower power factor means a more inductive circuit, which makes arc interruption harder. At moderate fault levels (6-20 kA), IEC 60947-2 tests at a significantly lower power factor than IEC 60898 — so the same numerical kA rating is actually a more demanding test under IEC 60947-2.

IEC 60898 vs IEC 60947-2: Side-by-Side Comparison

Utilization Categories: Cat A vs Cat B

IEC 60947-2 defines two utilization categories that have no equivalent in IEC 60898:

• Category A (non-selective): The breaker has no intentional short-time delay. It trips instantaneously on any fault within its breaking capacity. Most MCCBs under 630 A are Category A.
• Category B (selective): The breaker includes a short-time delay function, allowing it to remain closed for a defined period (typically 100-500 ms) while a downstream breaker clears the fault. This is essential for time-graded selectivity in multi-tier distribution. ACBs and large-frame MCCBs (800-2,500 A) with electronic trip units are typically Category B.

If your specification requires "selective protection" or "time-graded coordination," you need Category B breakers per IEC 60947-2 — IEC 60898 MCBs cannot provide this function.

Dual-Certified Devices: What Does "60898 / 60947-2" Mean?

Some MCBs carry both IEC 60898 and IEC 60947-2 certifications. This means the manufacturer has submitted the same device for testing under both standards. However, the rated values may differ:

• An MCB might be rated Icn = 10 kA per IEC 60898 and Icu = 15 kA / Ics = 7.5 kA per IEC 60947-2
• The IEC 60947-2 Icu is typically higher because the test power factor is different, and the standard's test sequence is more demanding — making a passing result at a higher current more meaningful
• Always check which standard the kA rating refers to when comparing products from different manufacturers

Common Specification Mistakes

From our experience supplying circuit breakers to international projects, these are the most frequent errors we see in specifications and purchase orders:

1. "6 kA MCB" without specifying the standard. A 6 kA Icn (IEC 60898) device has been tested under less severe conditions than a 6 kA Icu (IEC 60947-2) device. If the project requires IEC 60947-2, a 6 kA IEC 60898 MCB may not be acceptable — even though the number looks the same.
2. Specifying IEC 60898 for an industrial application. If the installation involves qualified electricians, adjustable protection, or fault levels above 25 kA, IEC 60947-2 is the correct standard. Many industrial project specifications call for IEC 60947-2 compliance as a blanket requirement.
3. Ignoring Ics. An MCCB with Icu = 50 kA but Ics = 12.5 kA (25% ratio) will need replacement after interrupting anything close to a 50 kA fault. For critical circuits where the breaker must remain in service after a fault, specify Ics ≥50% of Icu or higher.
4. Assuming all "10 kA" breakers are equal. A 10 kA IEC 60898 breaker tested at 0.3 power factor is not the same as a 10 kA IEC 60947-2 breaker tested at 0.5 power factor. The IEC 60947-2 device has passed a harder test.

For Comparison: Medium-Voltage Standards (IEC 62271 Series)

While IEC 60898 and IEC 60947-2 cover low-voltage breakers (≤1,000 V), medium-voltage circuit breakers (1 kV - 52 kV) are governed by the IEC 62271 series. NAIJI Electric's core product lines — vacuum circuit breakers, SF6 circuit breakers, and gas-insulated switchgear — are designed, tested, and certified under IEC 62271. For a detailed walkthrough of medium-voltage standards, see our IEC 62271 switchgear standards guide.

Which Standard Should You Specify?

Need Circuit Breakers Certified to the Right Standard?

NAIJI Electric supplies low-voltage circuit breakers and switchgear assemblies tested to IEC 60947 / IEC 61439, plus medium-voltage breakers to IEC 62271. We can provide test certificates, type test reports, and coordination studies for your project submission.

Contact NAIJI Electric — switchgear and circuit breaker manufacturer since 2001, ISO 9001 / CE / CCC certified, factory direct.

Related guides: MCB vs MCCB Comparison | Types of Circuit Breakers | Circuit Breaker Ratings Explained | IEC 62271 Switchgear Standards