What does an electrical isolator do vs. a circuit breaker?

The fundamental difference between an electrical isolator and a circuit breaker lies in their function and operating capability.While both can interrupt a circuit, they are designed for entirely different purposes.

• An Electrical Isolator (also known as a disconnector) is a manually operated mechanical switch. Its primary purpose is to isolate a part of a circuit from the rest of the system to ensure safety during maintenance.It provides a visible air gap, giving a clear visual confirmation that the circuit is open and de-energized.Crucially, an isolator is an "off-load" device. It is not designed to interrupt current and must only be operated after the circuit has been de-energized by a circuit breaker. Opening an isolator while current is flowing (under load) would create a dangerous electrical arc, which could damage the equipment and cause severe injury.
• A Circuit Breaker is an automatic protection device.Its job is to protect an electrical circuit from damage caused by an overcurrent, typically resulting from an overload or a short circuit.It is an "on-load" device, meaning it is specifically designed to safely interrupt the flow of current, whether it's the normal operating current or a massive fault current. It contains an internal arc-quenching system (using air, oil, gas, or a vacuum) to extinguish the arc that forms when the current is broken.

Here is a summary of the key differences: