Which device trips when there is a difference between live and neutral currents?

• A. Overload protection via a fuse.
• B. Provides surge protection.
• C. Detects differences between live and neutral currents and trips to prevent shock.
• D. Controls the color of wires.

Answer: (D)

A device that trips when there is a difference between live and neutral currents is designed to detect leakage of current to earth. If all the current that leaves through the live conductor should return via the neutral, but some of it instead escapes to ground (for example through a person touching a live part), the currents in live and neutral become unbalanced. A residual current device senses this imbalance and quickly disconnects the circuit to reduce the risk of electric shock. This function is different from overload protection (which trips when current is too high) and from surge protection (which handles voltage spikes). It’s also not related to changing wire colors. In short, the device’s role is to monitor live versus neutral current and trip when they don’t match to keep people safe.