How to Read Circuit Breaker Markings and Labels?

In this article, we will look at what information is marked on IEC 60898-1-2019 compliant household circuit breakers.

Understanding Circuit Breaker Markings

Each circuit-breaker shall be marked in a durable manner with the following:

  • a) manufacturer’s name or trademark;
  • b) type designation, catalogue number or serial number;
  • c) rated voltage(s);

For universal circuit breakers corresponding to IEC 60898-2-2016, the rated voltage values are indicated for AC and DC with the corresponding symbols indicating these electrical currents. Rated AC voltage with the symbol ac voltage symbol (IEC 60417-5032:2002-10) and rated DC voltage with the symbol DC voltage symbol (IEC 60417-5031:2002-10).

  • d) rated current without symbol “A”, preceded by the symbol of instantaneous tripping (B, C or D; for universal circuit breakers indicate B or C). For example, the label “C 32” on a circuit breaker indicates that it has an instantaneous tripping C and a rated current of 32 A;
  • e) rated frequency if the circuit-breaker is designed only for one frequency – 50 or 60 Hz;
  • f) rated short-circuit capacity (Icn), in amperes. For universal circuit breakers corresponding to IEC 60898-2-2016, the value of this characteristic is marked as follows: rated short-circuit capacity for AC and DC in amperes in one rectangle, without the symbol A, if valid for both AC and DC (see Example 1 below). If the rated short-circuit capacity is different for AC and DC this shall be indicated in two adjacent rectangles, without the symbol A, with the symbol ac voltage symbol (IEC 60417-5032:2002-10) near the rectangle containing the AC value and with the symbol DC voltage symbol(IEC 60417-5031:2002-10) near the rectangle containing the DC value (see Example 2 below).

Example 1: rated short-circuit capacity example 1 Example 2: and Rated short-circuit capacity example 3

  • g) wiring diagram, unless the correct mode of connection is evident;
  • h) reference ambient air temperature, if different from 30 °C;
  • i) degree of protection (only if different from IP20);
  • j) for type D circuit-breakers: the maximum instantaneous tripping current, if higher than 20 In;
  • k) rated impulse withstand voltage Uimp if it is 2,5 kV.
  • l) making and breaking capacity on an individual protected pole of multipole circuit breakers (Icn1), if different from Icn.
  • m) time constant T15 within a rectangle, if applicable, associated with the marking for the short-circuit capacity at the time constant of 15 ms (see Example 3 below).

Example 3: Time constant example 3

Marking d) shall be readily visible when the circuit-breaker is installed. If, for small devices, the available space is insufficient, markings a), b), c), e), f), h), i), j) and l) may be put on the side or on the back of the circuit-breaker. Marking g) may be on the inside of any cover which has to be removed in order to connect the supply wires but shall not be on a label loosely attached to the circuit-breaker. Any other information not marked shall be given in the manufacturer’s documentation.

The suitability for isolation, which is provided by all circuit-breakers of this standard, may be indicated by the symbol IEC 60417-6169-1 symbol (IEC 60417-6169-1) on the device. When affixed, this marking may be included in a wiring diagram, where it may be combined with symbols of other functions, e.g. overload protection, or other symbols of IEC 60417. When the symbol is used on its own (i.e. not in a wiring diagram), combination with symbols of other functions is not allowed.

NOTE 1 – In the following countries: Denmark, Finland, Norway, Sweden and South Africa the marking of the symbol on the circuit-breaker is mandatory to indicate that the device provides isolation for the installation downstream. In these countries it is required that the symbol be clearly and unmistakably visible when the circuit-breaker is installed as in service and the actuator is accessible.

NOTE 2 – In Australia this marking on the circuit-breaker is mandatory but is not required to be visible after installation.

If a degree of protection higher than IP20 according to IEC 60529 is marked on the device, it shall comply with it, whichever the method of installation. If the higher degree of protection is obtained only by a specific method of installation and/or with the use of specific accessories (e.g. terminal covers, enclosures, etc.), this shall be specified in the manufacturer’s literature.

The manufacturer shall make available, on request, the I2t characteristic (energy limiting class). The manufacturer may indicate the I2t classification and mark the circuit-breakers accordingly.

For circuit-breakers other than those operated by means of push-buttons the open position shall be indicated by the symbol O (a circle) IEC 60417-5008 and the closed position by the symbol I (a short vertical straight line) IEC 60417-5007. Additional national symbols for this indication are allowed. Provisionally the use of this national indication alone is allowed. These indications shall be readily visible when the circuit-breaker is installed.

For circuit-breakers operated by means of two push-buttons, only the push-button designed for the opening operation shall be red and/or be marked with the symbol O (IEC 60417-5008).

Red shall not be used for any other push-button of the circuit-breaker.

If a push-button is used for closing the contacts and is clearly identified as such, its depressed position is sufficient to indicate the closed position.
If a single push-button is used for closing and opening the contacts and is identified as such, the button remaining in its depressed position is sufficient to indicate the closed position. On the other hand, if the button does not remain depressed, an additional means indicating the position of the contacts shall be provided.
For circuit-breakers with multiple current ratings, the maximum value shall be marked in accordance with marking d), and in addition the value for which the circuit-breaker is adjusted shall be indicated without ambiguity.
If it is necessary to distinguish between the supply and the load terminals, the former shall be indicated by arrows pointing towards the circuit-breaker and the latter by arrows pointing away from the circuit-breaker.

Terminals intended exclusively for the neutral shall be indicated by the letter N.

Terminals intended for the protective conductor, if any, shall be indicated by the symbol: Protective earthing symbol(IEC 60417-5019).

The terminals shall be marked with + or if necessary. Additionally, arrows indicating the direction of the current are allowed.

For rail-mounted circuit-breakers, appropriate rail(s) shall be indicated in the manufacturer’s documentation.
Marking shall be indelible and easily legible, and shall not be placed on screws, washers or other removable parts.

What Do the Numbers and Letters on a Circuit Breaker Mean?

Examples of circuit breaker markings are shown below.

Example 1:

ABB S 200 series single pole circuit breaker marking
Figure 1. S 200 series single pole circuit breaker marking (ABB)

Figure 1 shows:

  • 1 – manufacturer’s trademark;
  • 2 – serial number;
  • 3 – Instantaneous trip type C, rated current 16 A;
  • 4 – rated operating voltage 230/400 V;
  • 5 – rated short-circuit capacity of 6000 A;
  • 6 – energy limiting class 3;
  • 7 – push-button (disabled position).

Example 2:

ABB S 290 Series Two-Pole Circuit Breaker Marking
Figure 2. Two-pole circuit breaker marking S 290 series (ABB)

Figure 2 shows:

  • 1 – manufacturer’s trademark;
  • 2 – serial number;
  • 3 – Instantaneous trip type C, rated current 16 A;
  • 4 – rated operating voltage of 400 V;
  • 5 – rated short-circuit capacity of 10000 A;
  • 6 – position indicator
  • 7 – push-button (disabled position).

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