Circuit breaker 3P ETI B-20A 10 kA — miniature thermal-magnetic three-pole protection

Three-pole ETI miniature circuit breaker B-20A 10 kA is a compact DIN-rail mountable device designed to protect three-phase electrical circuits against overloads and short circuits. With a B characteristic curve and thermal-magnetic trip, it offers reliable, selective disconnection of faulty circuits in residential, commercial or light industrial installations while occupying minimal panel space.

Advantages

The ETI B-20A 10 kA circuit breaker combines thermal and magnetic protection in a single compact unit, ensuring both long-term overload protection and instantaneous disconnection in case of short circuits. Its B characteristic curve provides sensitivity to low-magnitude faults typical for resistive loads and general-purpose circuits. The device is DIN-rail mountable for straightforward installation, and its rated breaking capacity helps ensure safe interruption of fault currents up to 10 kA.

Suitable for

• Protection of three-phase branch circuits in homes and apartments
• Distribution boards in small commercial premises and offices
• Light industrial panels with predominantly resistive or mixed loads
• Circuits supplying lighting, socket outlets and small motors

When it may not be suitable

This breaker may not be appropriate for installations that require specific time-delayed characteristics, advanced selective coordination beyond its thermal-magnetic design, or extremely high short-circuit current interruption well above 10 kA. It is not a substitute for devices providing earth-fault/ground-fault protection where required by local regulations.

Key specifications

• Poles: 3 (three-pole)
• Rated current: 20 A
• Tripping characteristic: B curve (thermal-magnetic)
• Rated ultimate breaking capacity: 10 kA
• Mounting: DIN-rail
• Function: overcurrent and short-circuit protection for three-phase circuits

How to use

Install the breaker on a standard DIN-rail inside a suitable distribution enclosure, observing correct orientation and torque for terminal connections. Connect the three phase conductors to the line terminals and the outgoing load conductors to the load terminals, ensuring secure tightening and proper conductor preparation. After installation, switch the device on and verify correct operation by observing that the breaker remains closed under normal load and trips when a simulated overload or short-circuit test (performed according to safety procedures) is applied. Follow local electrical codes and isolate power before any wiring work.

What to consider before purchase

• Verify that 20 A rated current and B characteristic suit the circuit load profile
• Confirm the installation environment and DIN-rail type compatibility
• Ensure required short-circuit breaking capacity of 10 kA meets site fault level
• Check whether additional protective functions (RCD/RCBO) are required by regulation

Usage recommendations

For reliable operation, pair the breaker with properly sized conductors and coordinated upstream protection. Schedule periodic visual inspections and functional tests within the intervals recommended by local standards, and replace devices that show mechanical wear or frequent tripping after the underlying fault is addressed.