Electrical Distribution

Circuit Breakers

Miniature and residual current circuit breakers. 9 products from 1 brand.

About circuit breakers

Miniature circuit breakers (MCBs) protect cables and equipment against overload and short circuit: a thermal element trips on sustained overcurrent and a magnetic element trips instantly on a short circuit. Residual current circuit breakers (RCCBs) protect people and installations against earth leakage by comparing the current flowing out and back. An RCCB does not provide overcurrent protection, so it is always used together with an MCB or fuse on the same circuit. Both types mount on a standard 35 mm DIN rail in distribution boards and control panels, and are available in single-pole and multi-pole versions to suit single-phase and three-phase circuits.

This page lists 9 DIN-rail circuit breakers from Siemens, including miniature circuit breakers and residual current circuit breakers in different ratings and pole configurations. Use the filters to narrow the list by product type, open a product for its information sheet, and add the models you need to one quotation request.

All circuit breakers

9 products

Buying guide

Choosing a circuit breaker

Circuit breakers are selected for the circuit they protect. These are the points to check before you request a quotation.

01

Rated current and poles

Match the MCB's rated current to the cable and the load it protects, and choose the number of poles for the circuit: single-pole, single-pole plus neutral, two, three or four poles.

02

Tripping characteristic

MCBs to IEC 60898-1 have tripping curves B, C and D. Type B trips at three to five times rated current and suits resistive loads and long cable runs. Type C trips at five to ten times and suits most commercial and industrial loads. Type D trips at ten to twenty times and suits loads with high inrush, such as transformers and some motors.

03

Breaking capacity

The breaking capacity, given in kA, must be at least the prospective short-circuit current at the point of installation. Typical values are 6 kA and 10 kA, with higher ratings for installations close to the supply transformer. Where the fault level is higher than a breaker can interrupt on its own, an upstream device can provide back-up protection according to the manufacturer's coordination tables.

04

RCCB sensitivity

RCCBs are rated by residual operating current. 30 mA devices provide additional protection for people; 100 mA and 300 mA devices are used for fire and equipment protection, often upstream of 30 mA devices.

05

RCCB type

Type AC detects alternating residual currents only. Type A also detects pulsating DC residual currents from electronic equipment. Type F and type B are needed where loads such as variable speed drives, EV chargers or solar inverters can produce smooth DC or high-frequency leakage currents.

06

Standards and installation

In South Africa, low-voltage installations must comply with SANS 10142-1. Selection and installation of protective devices should be done or checked by a registered electrician.

Need a full list for a distribution board? Send us the circuits, ratings and quantities with your quotation request.

Typical applications

  • Distribution boards
  • Final circuits
  • Control panels
  • Commercial buildings
  • Industrial plants
  • Earth leakage protection

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