In the same RCD rating 32 A, 30 mA, AC, what does the 30 mA indicate?

In the same RCD rating 32 A, 30 mA, AC, what does the 30 mA indicate?

• A. The current rating of the device
• B. The maximum continuous load
• C. The trip current between phase and neutral
• D. The rated leakage current

Answer: (D)

The main idea is that an RCD has two numbers: the continuous current it can carry (In) and the residual current that will cause it to trip (IΔn). The 30 mA is the sensitivity to leakage current. It means the device will sense any current leaking to earth as an imbalance between what comes in on the live conductor and what returns on the neutral. When that leakage reaches about 30 mA, the RCD trips and cuts power to protect people from shock. This value is not the maximum continuous load the device can carry, nor is it the normal phase-to-neutral current during operation. It’s specifically the threshold of leakage current (to earth) that triggers disconnection. The “AC” designation just indicates the type of leakage waveform the device responds to.

The main idea is that an RCD has two numbers: the continuous current it can carry (In) and the residual current that will cause it to trip (IΔn). The 30 mA is the sensitivity to leakage current. It means the device will sense any current leaking to earth as an imbalance between what comes in on the live conductor and what returns on the neutral. When that leakage reaches about 30 mA, the RCD trips and cuts power to protect people from shock.

This value is not the maximum continuous load the device can carry, nor is it the normal phase-to-neutral current during operation. It’s specifically the threshold of leakage current (to earth) that triggers disconnection. The “AC” designation just indicates the type of leakage waveform the device responds to.