What Are the Different Types of Switchgear?

Switchgear is equipment used to control, protect, distribute, and isolate electrical power. A switchgear assembly may contain circuit breakers, switches, fuses, bus, controls, protection relays, metering, and other devices.

But "switchgear" is a broad term. Medium-voltage metal-clad switchgear, metal-enclosed switchgear, pad-mounted switchgear, generator paralleling gear, automatic transfer equipment, low-voltage switchgear, and switchboards can look and operate very differently.

Knowing which type of equipment you have is important because the specifications needed to source or replace it change by equipment family.

GridGear works with the following switchgear and power-distribution equipment families:

• Medium-Voltage Metal-Clad Switchgear
• Medium-Voltage Metal-Enclosed Switchgear
• Pad-Mounted Switchgear
• Generator Paralleling Switchgear
• Automatic Transfer Switches
• Automatic Transfer Switchgear
• Low-Voltage Switchgear
• Switchboards
• Replacement Medium-Voltage Circuit Breakers

Medium-Voltage Metal-Clad Switchgear

Metal-clad switchgear is a highly compartmentalized form of medium-voltage switchgear.

Major components such as circuit breakers, main bus, instrument transformers, and cable compartments are separated by grounded metal barriers. Metal-clad switchgear commonly uses drawout electrically operated circuit breakers.

IEEE C37.20.2 covers metal-clad switchgear and defines the construction, ratings, test requirements, and other characteristics of this equipment family.

Common identifying information

• Voltage class
• Actual system voltage
• Main bus continuous-current rating
• Breaker interrupting rating
• Short-time or short-circuit rating
• BIL
• Breaker type
• Lineup configuration
• Number of sections
• Indoor or outdoor enclosure
• Existing manufacturer and equipment family when matching or replacing gear

Medium-Voltage Metal-Enclosed Switchgear

Medium-voltage metal-enclosed switchgear is also enclosed in metal, but it does not require the same degree of internal compartmentalization as metal-clad switchgear.

Depending on the design, it may use:

• Fused load-interrupter switches
• Non-fused switches
• Vacuum switching devices
• Circuit breakers
• Power fuses
• Controls and metering

IEEE C37.20.3 covers metal-enclosed interrupter switchgear above 1 kV AC within the scope of that standard.

Common identifying information

• Voltage class
• System voltage
• Bus or continuous-current rating
• Short-circuit rating
• BIL
• Primary switching or interrupting device
• Lineup configuration
• Indoor or outdoor construction
• Existing manufacturer and equipment family when matching existing gear

Metal-Clad vs. Metal-Enclosed: What Is the Difference?

This is one of the most common switchgear terminology issues.

Metal-clad switchgear

• Greater internal compartmentalization
• Grounded metal barriers separate major components
• Commonly uses drawout medium-voltage circuit breakers
• Often selected for systems where maintainability, protection, reliability, and operating flexibility justify the design

Metal-enclosed switchgear

• Less internal compartmentalization is required
• May use fused switches, fuses, breakers, or other switching devices
• Often used for transformer primary switching, distribution, sectionalizing, and other commercial or industrial applications

They are not interchangeable terms. Identifying which construction you have changes the information needed for sourcing.

Pad-Mounted Switchgear

Pad-mounted switchgear is outdoor medium-voltage distribution equipment designed for underground electrical systems.

It is typically low-profile, tamper-resistant equipment installed above grade and can be used for:

• Utility distribution
• Feeder sectionalizing
• Loop systems
• Fault isolation
• Underground commercial and industrial distribution

Unlike an indoor metal-clad lineup, pad-mounted switchgear is often described in terms of ways, switching or interruption devices, insulation medium, and radial or loop configuration.

IEEE C37.74 addresses subsurface, vault, and pad-mounted load-interrupter switchgear and fused load-interrupter switchgear within the scope of that standard.

Common identifying information

• Voltage
• Continuous-current rating
• Fault-interrupting rating
• BIL where applicable
• Number of ways
• Switch or interrupter type
• Insulation medium
• Radial, loop, or sectionalizing configuration
• Front or operating configuration

Generator Paralleling Switchgear

Generator paralleling switchgear controls and coordinates multiple power sources, especially multiple generators and, in some systems, generators operating in parallel with utility sources.

Its job goes beyond simply moving a load from one source to another. A paralleling system may synchronize generators, connect multiple sources to a common bus, share load, sequence generator operation, and manage utility/generator interaction.

These systems can include:

• Generator breakers
• Utility breakers
• Main and tie breakers
• Synchronizing controls
• Load-sharing controls
• Protective relays
• Metering and automation

Generator paralleling switchgear is especially relevant in facilities with substantial onsite or standby generation, including data centers, healthcare facilities, industrial plants, and other critical-power applications.

Common identifying information

• System voltage
• Main bus rating
• Short-circuit rating
• Generator count
• Total generator capacity
• Utility source count
• System configuration
• Utility-paralleling requirements
• Control and synchronization requirements

Automatic Transfer Switches (ATS)

An automatic transfer switch transfers a load between two power sources, commonly a normal utility source and an alternate generator or second utility source.

The ATS monitors source conditions and initiates transfer when the preferred source becomes unavailable or unacceptable.

Common identifying information

• Ampere rating
• System voltage
• Number of poles
• Source arrangement
• Transition type, such as open, delayed, or closed transition
• Withstand and closing rating
• Bypass-isolation requirement
• Enclosure
• Application requirements

Automatic Transfer Switchgear

Automatic transfer switchgear performs a similar source-transfer function but may use a larger switchgear or switchboard assembly with breakers, bus, controls, ties, and transfer logic integrated into the lineup.

Common arrangements can include:

• Main-Tie-Main
• Utility-Generator
• Multiple utility sources
• Multiple generator sources
• Automatic breaker-transfer schemes

A standalone ATS and an automatic transfer switchgear lineup are not necessarily the same physical product, even though both solve a source-transfer problem.

Common identifying information

• Voltage
• Bus or continuous-current rating
• Short-circuit rating
• Transfer scheme
• Transition type
• Number and type of sources
• Construction standard
• Enclosure and access arrangement

Low-Voltage Switchgear

Low-voltage switchgear distributes and protects electrical power on low-voltage systems and is commonly used in high-current commercial, industrial, and critical-power applications.

Low-voltage switchgear commonly uses low-voltage power circuit breakers, often in drawout construction, and is designed around substantial bus and short-circuit ratings.

Common identifying information

• System voltage
• Bus rating
• Short-circuit rating
• Breaker type
• Lineup configuration
• Access arrangement
• Service-entrance requirements
• Indoor or outdoor construction

Switchboards

Switchboards also distribute low-voltage electrical power, but their construction and protective devices can differ from low-voltage switchgear.

A switchboard may use:

• Molded-case circuit breakers
• Insulated-case circuit breakers
• Main and feeder devices
• Group-mounted or individually mounted distribution sections

In North America, low-voltage switchgear and switchboards are also commonly associated with different product standards, including UL 1558 for low-voltage switchgear and UL 891 for switchboards.

Low-voltage switchgear vs. switchboard

Although the terms are sometimes used casually, they are not simply two names for the same equipment.

Low-voltage switchgear generally uses more compartmentalized construction and low-voltage power circuit breakers, frequently in drawout configurations. Switchboards commonly use molded-case or insulated-case devices and may use different mounting, access, and construction arrangements.

When sourcing a replacement or expansion, identifying which equipment family is installed matters.

Replacement Medium-Voltage Circuit Breakers

A replacement medium-voltage circuit breaker is not an entire switchgear lineup, but it is an important part of the switchgear sourcing market.

Existing installations may need:

• An OEM spare breaker
• A replacement for a failed breaker
• A retrofit
• A retrofill
• A compatible breaker for obsolete gear

For these requirements, electrical ratings alone are usually not enough. Physical and mechanical compatibility with the existing cubicle can be critical.

Common identifying information

• Existing switchgear manufacturer
• Switchgear family or model
• Breaker manufacturer and model
• Voltage class
• Continuous-current rating
• Interrupting rating
• Breaker technology
• Racking or mounting mechanism
• Cell or cubicle identity
• Control-power or coil-voltage information where relevant

One-line drawings, switchgear drawings, breaker nameplates, and clear equipment photos can be extremely useful for replacement-breaker sourcing.

Switchgear Categories Can Overlap

Switchgear terminology can describe different aspects of the same power system.

For example:

• Generator paralleling controls may be incorporated into low- or medium-voltage switchgear.
• Automatic transfer functionality may exist in a standalone ATS or inside an integrated switchgear lineup.
• A unit substation can incorporate a transformer plus switchgear or a switchboard.
• Replacement breakers are components of switchgear, not entire assemblies.

So identifying existing equipment often requires more than reading the label on the front door.

The next useful step is usually to gather the nameplate, one-line diagram, lineup drawings, breaker information, and equipment photos.

What Ratings Matter Most When Identifying Medium-Voltage Switchgear?

For medium-voltage equipment, the most useful electrical identity usually includes:

Primary ratings

• Equipment type
• Voltage class or rated maximum voltage
• Actual system voltage
• Continuous-current or bus rating
• Short-circuit or short-time withstand rating
• Breaker interrupting rating where applicable
• BIL
• Frequency where known

Construction and device identity

• Metal-clad vs. metal-enclosed
• Circuit breaker vs. fused switch or other primary device
• Drawout vs. fixed construction where relevant
• Indoor vs. outdoor
• Lineup configuration

Matching and replacement information

When the requirement involves existing equipment, also gather:

• Manufacturer
• Equipment family or model
• One-line diagram
• Shop or lineup drawings
• Section or cubicle identity
• Breaker model
• Racking information
• Physical interface details

You do not need every one of these items before GridGear can begin reviewing the requirement.

Need Help Identifying or Sourcing Switchgear?

If you know the equipment family and ratings, send them. If you are not sure whether you have metal-clad, metal-enclosed, pad-mounted, transfer, paralleling, or another type of equipment, send the information you have.

A nameplate, one-line, lineup drawing, old quote, breaker information, or clear photos can often provide enough information to begin narrowing the requirement.

GridGear works with buyers to source hard-to-find switchgear and related power-distribution equipment across new surplus, unused, remanufactured, and used markets.

Request a Switchgear Quote

Technical References

This resource is GridGear-authored educational content informed by industry standards and technical references. Relevant standards include:

• IEEE C37.20.2 — Metal-Clad Switchgear
• IEEE C37.20.3 — Metal-Enclosed Interrupter Switchgear
• IEEE C37.74 — Subsurface, Vault, and Pad-Mounted Load-Interrupter Switchgear
• UL 1558 — Metal-Enclosed Low-Voltage Power Circuit Breaker Switchgear
• UL 891 — Switchboards

Standards define equipment requirements more precisely than this introductory guide and should be consulted when formal engineering or procurement compliance is required.