What is the difference between B, C, and D curve MCBs?

They have different instantaneous magnetic tripping ranges for short-circuit protection: B-type (3-5 In), C-type (5-10 In), and D-type (10-20 In), as defined in Clause 5.3.6 and Table 7.

What does the number in a box, like '10000', on an MCB mean?

It indicates the rated short-circuit breaking capacity (Icn) in Amperes, e.g., 10,000 A or 10 kA, as per the marking requirements in Clause 6.

Can I use an MCB from this standard in an industrial panel?

No, this is for household and similar installations. For industrial applications with higher breaking capacity or coordination needs, use breakers compliant with IS/IEC 60947-2.

What is the maximum rated current covered by this standard?

The standard covers circuit-breakers with a rated current (In) not exceeding 125 A. (Clause 1)

IS/IEC 60898 Part 1

: 2002

Electrical accessories - Circuit-breakers for overcurrent protection for household and similar installations - Part 1: Circuit-breakers for ac operation

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This standard specifies requirements for AC miniature circuit breakers (MCBs) used for overcurrent protection in household and similar low-voltage installations up to 440V. It defines their classification (B, C, D curves), construction, performance characteristics, and testing methods to ensure safety against overload and short-circuits. It is the fundamental standard for all MCBs used in residential and commercial buildings.

Specifies requirements for circuit-breakers for overcurrent protection of household and similar installations designed for operation with alternating current.

Quick Reference Values

Standard Rated Currents6, 10, 16, 20, 25, 32, 40, 50, 63 Amperes

Instantaneous Tripping (Type B)3 to 5 times rated current (In)

Instantaneous Tripping (Type C)5 to 10 times rated current (In)

Instantaneous Tripping (Type D)10 to 20 times rated current (In)

Standard Rated Voltage240/415 V AC

Common Rated Short-Circuit Capacity (Icn)6000 A (6kA) and 10000 A (10kA)

Conventional Tripping Current1.45 times rated current (In)

Conventional Non-Tripping Current1.13 times rated current (In)

Practical Notes

Type C is the most common for general purpose loads (lighting, sockets). Type B is for sensitive or resistive loads. Type D is for high inrush current loads like motors and transformers.

Ensure the Short Circuit Breaking Capacity (Icn) of the MCB is higher than the prospective short circuit current (PSCC) at the point of installation for safety.

This standard is for AC operation only. For DC applications, refer to IS/IEC 60898-2.