An RCD is rated 30 mA - Leaving Cert Physics - Question i - 2006

The rating of 30 mA for a Residual Current Device (RCD) indicates the threshold at which the device will activate to protect individuals from potential electric shock. This threshold is crucial because it represents the level of current leakage that is deemed safe when using electrical equipment in residential and commercial settings.

Safety Threshold

Current levels above 30 mA can pose a significant risk of electric shock or electrocution. Therefore, the RCD is designed to detect any imbalance between the live and neutral wires.

Functionality

When the leakage current reaches 30 mA or more, the RCD quickly reacts by tripping, disconnecting the electrical circuit. This rapid response helps to minimize the risk and potential harm to individuals who may come into contact with faulty appliances or wiring.

Compliance and Standards

In many regions, RCDs rated at 30 mA are standard for domestic and outdoor use as they conform to electrical safety regulations. The use of such RCDs is crucial in environments where there is an increased risk of electrical faults, thus enhancing overall safety.

Conclusion

In summary, the significance of the 30 mA rating is primarily related to its effectiveness in protecting human life by preventing electric shocks due to leakage currents.