CTEC Residual Current Circuit Breakers

Techna’s Ctec range provides stylish and cost effective residual current (earth leak) fault protection in both 2 and 4 poles. An RCCB, also known as a Residual Current Device (RCD) or Earth Leakage Circuit Breakers (ELCB) has two basic functions: a) To help protect plant and equipment against fires which can often be caused by relatively low fault current from live to earth, which a fuse or circuit breaker may not detect. b) To prevent fatal electric shock to personnel, by reducing (but not eliminating), the length of time a person is exposed to current flow through the body. Note: The Ctec RCCB device does not provide overload or short circuit protection and should be used in conjunction with a miniature circuit breaker (Gtec or Jtec). Standard devices are for AC systems. Special versions are also available to order for combined AC and DC pulse protection.

The RCD protects against residual currents (earth leaks), where a small current may leak from the circuit due to bad insulation. Critically the residual current device will react to leakage currents as low as 30mA (or 10mA available to order). This is an essential protection requirement as earth leaks at these low currents are too small to trip a conventional circuit breaker, but still large enough to cause fatal electric shocks and/or start fires due to arcing. The sensitivity of the RCD is defined by its mA rating. The main current rating of the device denotes only the maximum current the RCD can carry and does not affect the protection characteristics. So, for example, if you required a 25A/30mA RCD, you could also use a 40A/30mA or 63A/30mA. However, the lower current device (25A) costs less as the lower rated contact mechanism is less expensive to produce.

Techna also offer devices which are classed as Type A RCDs. The Type A designation denotes that the device is suitable for protecting against dc pulses in addition to basic ac earth leaks. These are available as a special order.

None of the residual current devices shown give protection against overloads, so for complete safety they should be used in conjunction with a conventional circuit breaker.


Download more information on CTEC RCCBs (PDF 166KB)