| Low-Voltage Switch Disconnector | Provides a visible or mechanically indicated open circuit by separating contacts from the electrical supply. | Up to 1,000 V AC or 1,500 V DC | 16–1,600 A | Main distribution boards Control panels Motor circuits | Manual handle, load-break capability on suitable models, padlockable operating position, and optional door interlock. | IEC 60947-3; IEC 61439 when installed in a low-voltage assembly. |
| Medium-Voltage Indoor Isolator | Creates an isolation gap in a medium-voltage circuit after the circuit has been interrupted by an appropriate circuit breaker or load-break device. | Typically 3.6–36 kV | 200–3,150 A | Indoor substations Industrial feeders Transformer incomers | Fixed or withdrawable construction, mechanical position indication, earthing-switch coordination, and interlocking to prevent unsafe operation. | IEC 62271-102; IEC 62271-200 for metal-enclosed switchgear assemblies. |
| Load-Break Isolating Switch | Can interrupt specified normal load current in addition to providing electrical isolation; it is not a substitute for a fault-interrupting circuit breaker unless rated for that duty. | Up to 1,000 V AC in low-voltage systems; commonly up to 36 kV in medium-voltage systems | 63–2,500 A | Feeder sections Transformer switching HVAC systems | Arc-control system, rapid contact movement, load-break rating, and optional fuses or earth-switch assembly. | IEC 60947-3 for low voltage; IEC 62271-103 for medium-voltage switches. |
| Fused Isolating Switch | Combines switching and isolation with overcurrent protection provided by replaceable or withdrawable fuses. | Up to 1,000 V AC | 32–800 A | Motor protection Distribution feeders Commercial buildings | Fuse-link protection, shrouded terminals, door coupling, clear ON/OFF indication, and padlockable isolation. | IEC 60947-3; fuse coordination commonly follows IEC 60269. |
| Changeover Isolator | Transfers a load between two separate sources while maintaining a defined isolated position between source selections. | Up to 1,000 V AC | 40–1,600 A | Generator changeover Emergency power UPS bypass systems | Manual or motorized operation, mechanically stable source positions, source interlocking, and optional remote indication. | IEC 60947-6-1 for transfer switching equipment; IEC 60947-3 for switch-disconnector functions. |
| Earthing Switch | Connects an isolated circuit to protective earth so that stored or induced electrical energy can be safely discharged before maintenance. | Commonly 3.6–36 kV in indoor medium-voltage equipment | Rated mainly by short-time withstand current rather than continuous load current | Switchgear panels Cable compartments Transformer bays | High-speed or slow-closing mechanism, short-circuit making capability on specified models, visible position indication, and safety interlocking. | IEC 62271-102. |
| Withdrawable Switchgear Isolator | Achieves isolation by moving a circuit-breaker or switching module from the connected position to the test or disconnected position. | Typically 3.6–36 kV | 630–4,000 A | Data centers Process plants Utility substations | Shuttered primary contacts, racking mechanism, test position, service position, and key or mechanical interlocks. | IEC 62271-200; applicable circuit-breaker requirements may include IEC 62271-100. |
| Enclosed Indoor Isolator | Places the switching mechanism and live terminals inside a protective enclosure to limit accidental contact and contain installation hazards. | Up to 1,000 V AC | 20–630 A | Workshops Plant rooms Commercial facilities | Insulated or metal enclosure, cable entry provisions, external rotary handle, IP-rated construction, and optional auxiliary contacts. | IEC 60947-3; enclosure ingress protection is commonly classified under IEC 60529. |
| PV DC Isolator | Separates photovoltaic strings or arrays from inverters and other equipment under direct-current conditions. | Up to 1,500 V DC | 16–630 A | Rooftop PV Solar combiner boxes Battery-coupled PV systems | DC-rated contact spacing, polarity-specific design, arc suppression, UV-resistant enclosure options, and lockable OFF position. | IEC 60947-3 and applicable photovoltaic switching requirements under IEC 60947-1 and local installation codes. |
| Typical Selection Criteria | Selection depends on the system voltage, current, fault level, switching duty, installation category, environmental conditions, and required maintenance procedure. | Must match or exceed the system’s nominal voltage and insulation requirements. | Must match continuous load current and applicable short-time withstand requirements. | Indoor temperature Humidity Altitude Pollution level | Check isolation suitability, utilization category, terminal capacity, IP rating, creepage and clearance, interlocking, certification, and availability of replacement parts. | Always verify the latest edition of the applicable IEC, national, and local electrical installation standards. |