Types of Electrical Switchgear: Complete Classification Guide (2026)

Overview: How Switchgear Is Classified

Switchgear is not a single product — it is a broad family of equipment used to control, protect, and isolate electrical circuits. Engineers classify switchgear along five dimensions, and understanding these classifications is essential for specifying the right equipment.

1. Types by Voltage Level

Low Voltage Switchgear (below 1 kV)

LV switchgear operates at 230-690 V and distributes power within buildings and facilities. It uses air circuit breakers (ACB), molded case circuit breakers (MCCB), and miniature circuit breakers (MCB) as protective devices.

Common types include draw-out switchgear panels (like the GCS series, up to 4000 A), fixed-type panels (like the GGD series), and motor control centers (MCCs). The EZMX1 air circuit breaker (up to 6300 A / 135 kA) is one of the world's most compact ACBs used in LV main incoming panels.

Medium Voltage Switchgear (1 kV - 52 kV)

MV switchgear is the largest and most diverse category. It uses vacuum or SF6 circuit breakers and serves as the backbone of power distribution networks. The most common ratings are 12 kV, 24 kV, and 40.5 kV.

NAIJI Electric's MV lineup spans the full range: metal-enclosed switchgear panels (ASN series), gas-insulated switchgear (GSN series), outdoor vacuum circuit breakers (ZW32), and indoor vacuum circuit breakers (VN/CE/CVG series).

High Voltage Switchgear (above 52 kV)

HV switchgear operates at transmission voltages (66 kV to 800 kV) and is typically installed in large outdoor substations or as GIS in compact indoor substations. It uses SF6 as the primary interrupting and insulating medium at these voltage levels.

2. Types by Insulation Medium

Air-Insulated Switchgear (AIS)

AIS uses atmospheric air for insulation between live parts. It is the simplest, most economical, and most widely used type at both LV and MV levels. Air provides adequate insulation at moderate voltages but requires larger clearance distances than gas insulation.

• Advantages: Low cost, simple construction, easy to inspect and extend, no gas handling
• Disadvantages: Large footprint, sensitive to dust/humidity/pollution, requires regular cleaning
• Example: ASN3-12 — 12 kV AIS with vacuum circuit breakers, up to 5000 A / 50 kA

Gas-Insulated Switchgear (GIS)

GIS encloses all live components in sealed metal housings filled with an insulating gas, typically SF6 or nitrogen. The superior dielectric strength of the gas allows 50-80% size reduction compared to AIS.

• Advantages: Extremely compact, immune to environment, maintenance-free gas compartment, excellent reliability
• Disadvantages: Higher cost, requires gas handling for maintenance, SF6 is a potent greenhouse gas
• Example: GSN3-12 — 12 kV C-GIS with eco-friendly nitrogen insulation, 3150 A / 40 kA

For a detailed comparison, see our guide: What Is Gas-Insulated Switchgear (GIS)?

Vacuum-Insulated Switchgear

While vacuum is primarily used as an arc-extinguishing medium inside interrupters, some modern designs use vacuum for both switching and insulation, eliminating the need for any gas. This emerging technology is still maturing but represents the future of truly SF6-free switchgear.

Oil-Insulated Switchgear

Oil circuit breakers use mineral oil for both insulation and arc extinguishing. Once dominant at MV and HV, they have been largely replaced by vacuum and SF6 technology due to fire risk, maintenance burden, and environmental concerns. Oil breakers are still found in older installations worldwide.

3. Types by Construction

Metal-Clad Switchgear

The highest level of construction: grounded metal barriers separate every functional compartment (bus, breaker, cable, control). The circuit breaker must be draw-out (withdrawable). Automatic shutters seal openings when the breaker is removed. Provides the best arc containment and maintenance safety.

Metal-Enclosed Switchgear

A grounded metal enclosure surrounds the assembly, but internal barriers between compartments are not mandatory. Can use either draw-out or fixed-mount breakers. More compact and cost-effective than metal-clad.

For a detailed comparison: Metal Clad vs Metal Enclosed Switchgear

Open-Type Switchgear

Components mounted on open frames without full enclosure. Used mainly at high voltage in outdoor substations where equipment is spaced far apart. Rarely used at medium voltage in modern installations.

4. Types by Installation

Indoor Switchgear

Designed for installation in electrical rooms, substations, or buildings. Protected from weather but requires adequate ventilation and clearance space. Most MV switchgear in commercial and industrial settings is indoor type.

• Examples: ASN3-12, ASN2-24, ASN1-40.5 panels; VN3-12E, CE-12 circuit breakers

Outdoor Switchgear

Designed to withstand rain, sun, wind, ice, and temperature extremes. Uses weatherproof enclosures (IP ratings) or inherently weather-resistant construction. Common for distribution networks and rural substations.

• Examples: ZW32-12 pole-mounted VCB; FZW28-12 boundary switch

Pole-Mounted Switchgear

A subset of outdoor switchgear mounted directly on overhead line poles. Used extensively in rural and semi-urban distribution networks. Includes pole-mounted circuit breakers, load break switches, and reclosers.

Underground / Pad-Mounted

Installed at ground level or below ground in urban areas where overhead lines are not permitted. Ring main units (XGN15-12) are the primary switchgear type for underground cable networks.

5. Types by Function

Circuit Breaker Panels

The core function: contain a circuit breaker for protecting and switching feeders, transformers, generators, or motors. Available with vacuum breakers (VCB) or SF6 breakers.

Ring Main Units (RMU)

Compact switchgear for cable distribution networks, combining load break switches and fuse switches in modular configurations. Used at every distribution point in urban underground networks. XGN15-12 offers multiple module combinations (2L+1F, 2V+1F, etc.).

Load Break Switch Panels

Contain load break switches (LBS) for sectionalizing feeders. Can interrupt load current but not fault current. Often used at distribution branch points and customer boundaries.

Contactor Panels

Contain vacuum contactors for frequent switching of motors and capacitor banks. Designed for high duty cycles (hundreds of thousands of operations) that would wear out a circuit breaker.

Motor Control Centers (MCC)

Specialized LV or MV switchgear assemblies containing multiple motor starter units. Each unit includes a contactor or circuit breaker, overload relay, and control circuitry for one motor. GCS draw-out switchgear is commonly used as the platform for LV MCCs.

Metering Panels

Contain voltage and current transformers for revenue metering and system monitoring. Often combined with a disconnect switch or circuit breaker in the same switchgear lineup.

How to Select the Right Type

For project-specific switchgear selection guidance, contact the NAIJI Electric engineering team.