Please note: Why electronic residual current devices do not belong on construction sites

What is the problem with electronic residual current devices?

Electronic residual current devices (RCDs) only work when live. This seems logical, but especially on a construction site, it can be extremely dangerous. Unlike mechanical RCDs, electronic versions can:

Do not respond when voltage is lost – exactly when extra security is required.
No fault detection in case of break in the neutral conductor.
Unreliable operation during voltage dips or phase failures.

NEN-EN-IEC 61439-4 therefore explicitly specifies functional requirements for components in building distribution boards. These protective components must remain functional at all times, even in the event of a voltage drop or external fault current. Electronic residual current devices (RCDs) do not meet these requirements.

Practical example

Suppose a construction distribution box is powered via an extension cord. Due to intensive use by excavators or heavy vehicles, the cord becomes damaged, and a break occurs in the neutral conductor.
When the power to this extension cord fails, all electronic earth leakage circuit breakers in the distribution box no longer function, because they rely on external power to perform their protection function.

Create a mechanical earth leakage circuit breaker On the other hand, it remains active even without mains power, and the system can still switch off in the event of a fault current. This prevents parts of the system from remaining live while users think everything is safe. Electronic RCDs lack this crucial safety feature, which can lead to life-threatening situations.

Why are they used anyway?

We still see electronic residual current devices (RCDs) in the field. Why?

Lack of knowledge with installers or buyers.
Lower purchase price than mechanical alternatives.
Compact design: 1 module wide instead of 2 – which saves space (and therefore costs) in the distribution box.

But: This saving comes at the expense of safety.