How to Read Residual Current Device (RCD) Markings?

In this article, we will look at what information is marked on household residual current devices (RCCBs and RCBOs) that comply with IEC 61008-1 and IEC 61009-1.

Marking and Other Product Information for RCCB

Each RCCB shall be marked in a durable manner with all or, for small apparatus, part of the following data:

  • a) the manufacturer’s name or trademark;
  • b) type designation, catalogue number or serial number;
  • c) rated voltage(s) Un;
  • d) rated frequency; RCCBs with more than one rated frequency (e.g. 50/60 Hz) shall be marked accordingly;
  • e) rated current In;
  • f) rated residual operating current IΔn;
  • g) settings of residual operating current for RCCBs with multiple residual operating current settings;
  • h) rated making and breaking capacity Im;
  • j) the degree of protection (only if different from IP20);
  • k) the position of use, if necessary;
  • l) rated residual making and breaking capacity IΔm, if different from rated making and breaking capacity;
  • m) the symbol symbol S (S in a square) for type S devices;
  • n) indication that the RCCB is functionally dependent on line voltage, if applicable (under consideration);
  • o) operating means of the test device, by the letter T;
  • p) wiring diagram;
  • q) operating characteristic in presence of residual currents with d.c. components

– RCCBs of type AC with the symbol RCBB AC symbol (IEC 60417-5032-2002-10)

– RCCBs of type A with the symbol RCBB type A

If, for small devices, the space available does not allow all the above data to be marked, at least the information under e), f), m), o) and q) (only for type A) shall be marked and visible when the device is installed. The information under a), b), c), k), l) ,p) and q) (only for type AC) may be marked on the side or on the back of the device and be visible only before the device is installed. Alternatively the information under p) may be on the inside of any cover which has to be removed in order to connect the supply wires. Any remaining information not marked shall be given in the manufacturer’s catalogues.

The manufacturer shall state the Joule integral I2t and the peak current Ip withstand capabilities of the RCCB. Where these are not stated, minimum values as given in Table 18 IEC 61008‑1 apply.

The manufacturer shall give the reference of one or more suitable SCPDs in his catalogues and in a sheet accompanying each RCCB.

Marking and Other Product Information for RCBO

Each RCBO shall be marked in a durable manner with all or, for small apparatus, part of the following data:

  • a) manufacturer’s name or trademark;
  • b) type designation, catalogue number or serial number;
  • c) rated voltage(s) Un;
  • d) rated current In without symbol “A”, preceded by the symbol of overcurrent instantaneous tripping (B, C or D), for example B 16;
  • e) rated frequency; RCBOs with more than one rated frequency (e.g. 50/60 Hz) shall be marked accordingly;
  • f) rated residual operating current IΔn;
  • g) settings of residual operating current for RCBOs with multiple residual operating currents;
  • h) rated short-circuit capacity Icn, in amperes;
  • j) reference calibration temperature, if different from 30 °C;
  • k) the degree of protection (only if different from IP 20);
  • l) the position of use, if necessary;
  • m) rated residual making and breaking capacity IΔm, if different from rated short-circuit capacity;
  • n) the symbol symbol S (S in a square) for type S devices;
  • o) indication that the RCBO is functionally dependent on line voltage, if applicable (under consideration);
  • p) operating means of the test device, by the letter T;
  • q) wiring diagram;
  • r) operating characteristic in presence of residual currents with d.c. components

– RCBOs of type AC with the symbol RCBB AC symbol (IEC 60417-5032-2002-10)

– RCBOs of type A with the symbol RCBB type A.

  • s) for type D RCBOs: the maximum instantaneous tripping current, if higher than 20 In (see Table 4 IEC 61009‑1).

If, for small devices, the space available does not allow all the above data to be marked, at least the information under d), f), n), p) and r) (only for type A) shall be marked and visible when the device is installed. The information under a), b), c), h) , l), r) (only for type AC) and s) may be marked on the side or on the back of the device and be visible only before the device is installed. The information under q) may be on the inside of any cover which has to be removed in order to connect the supply wires. Any remaining information not marked shall be given in the manufacturer’s catalogues.

General Requirements for RCD Marking

The marking shall be on the residual current device itself or on a nameplate or nameplates attached to the RCCB and shall be located so that it is legible when the RCCB is installed.

The suitability for isolation, which is provided by all RCDs of this standard, may be indicated by the symbol RCBB symbolon the device. When affixed, this marking may be included in a wiring diagram, where it may be combined with symbols of other functions.

NOTE 1. In Australia, this marking on the circuit-breaker is mandatory but is not required to be visible after installation.

When the symbol is used on its own (i.e. not in a wiring diagram), combination with symbols of other functions is not allowed.

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.

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

Terminals intended for the protective conductor, if any, shall be indicated by the symbol Class 1 Equipment Symbol(IEC 60417-5019-2006-08).

For RCDs other than those operated by means of push-buttons the open position shall be indicated by the symbol “O” and the closed position by the symbol ” | ” (a short straight line).

Additional national symbols are allowed for this indication. Provisionally, the use of national indications only is allowed. These indications shall be readily visible when the RCD is installed.

For RCDs operated by means of two push-buttons, the push-button designed for the opening operation only shall be red and/or be marked with the symbol “O”.

RED shall not be used for any other push-button of the RCD. If a push-button is used for closing the contacts and is evidently 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.

If it is necessary to distinguish between the supply and the load terminals, they shall be clearly marked (e.g. by “line” and “load” placed near the corresponding terminals or by arrows indicating the direction of power flow).

The marking shall be indelible, easily legible and not be placed on screws, washers or other removable parts.

The markings should appear on the RCD or, if the space available is not sufficient, on the smallest package unit or in technical information.

What Do the Numbers and Letters on a Residual Current device Mean?

Examples of RCD markings are shown below.

Example 1 (RCCB):

Two-pole RCCB Series F 200 marking
Figure 1. Two-pole RCCB Series ABB F 200 marking

Figure 1 shows:

  • 1 – manufacturer’s trademark;
  • 2 – serial number;
  • 3 – rated current In = 100 A;
  • 4 – rated voltage Un = 230 V;
  • 5 – rated making and breaking capacity Im and rated residual making and breaking capacity IΔm equal to 1000 A;
  • 6 – rated current of the fuse is 100 A;
  • 7 – rated conditional short-circuit current Inc = 10000 A;
  • 8 – operating means of the test device;
  • 9 – position indicator;
  • 10 – ambient air temperature from – 25 to + 40 oC;
  • 11 – RCCB designation of type AC;
  • 12 – rated residual operating current IΔn =  0,03 А;
  • 13 – push-button (disabled position).

Example 2 (RCBO):

Two-pole RCBO series DS 941 marking
Figure 2. Two-pole RCBO series ABB DS 941 marking

Figure 2 shows:

  • 1 – manufacturer’s trademark;
  • 2 – serial number;
  • 3 – operating means of the test device;
  • 4 – instantaneous tripping – C, rated current In = 16 A;
  • 5 – rated short-circuit capacity Icn = 4500A;
  • 6 – ambient air temperature from – 25 to + 40 oC;
  • 7 – rated voltage Un = 230 V;
  • 8 – push-button (disabled position);
  • 9 – RCBO designation of type A;
  • 10 – rated residual operating current IΔn =  0,03 А.

Example 3 (Residual current unit):

Two-pole RCU Series DDA 202 marking
Figure 3. Two-pole RCU Series DDA 202 marking

Figure 3 shows:

  • 1 – manufacturer’s trademark;
  • 2 – serial number;
  • 3 – operating means of the test device;
  • 4 – rated residual operating current IΔn =  0,03 А;
  • 5 – RCD designation of type A;
  • 6 – ambient air temperature from – 25 to + 40 oC;
  • 7 – RCD actuator acting on the holding device in the circuit breaker mechanism;
  • 8 – push-button (disabled position);
  • 9 – conductors intended for electrical connection of the RCD and circuit breaker.

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