Switchgear Services

Electrical switchgear is the assembly of circuit breakers, disconnects, fuses, busbar, current and potential transformers, and protective relays that controls and protects the flow of power into a building or substation. Think of it as the panel between the utility's transformer and your loads — only at scales where a fault inside the cabinet can release megawatts in milliseconds.

Switchgear is classified by voltage class — low voltage (≤1 kV, e.g., 480 V power circuit breaker switchgear), medium voltage switchgear (1–38 kV, the majority of industrial substations), and high voltage switchgear (>38 kV, mostly utility) — and by construction style. Metal-clad switchgear (the most common medium-voltage style in North America) isolates each circuit in its own grounded compartment with a removable, draw-out breaker. Metal-enclosed switchgear and metal-clad switchgear use overlap in casual use, but they are distinct ANSI definitions with different testing implications.

These three terms get used interchangeably in conversation but mean different things in code and on the bill of materials. Switchgear (NEMA SG-4, ANSI C37) is metal-enclosed equipment that uses draw-out or stationary power circuit breakers as the main interrupting device, with bus, insulators, and protective relays. It is the standard above 600 V and is also used at low voltage where higher fault duties or testability are required.

A switchboard (NEMA PB-2, UL 891) uses molded-case or insulated-case circuit breakers — or fused disconnects — instead of draw-out power breakers. Switchboards are common at 480 V and below in commercial buildings and small industrial facilities. They are smaller, cheaper, and have shorter expected lifecycles than switchgear, but cannot be racked out for maintenance the way switchgear can.

A high-voltage switch (or load-break switch, ANSI C37.30) is a single device, not an assembly. It opens and closes a circuit at distribution or transmission voltages, often used as a sectionalizer in pad-mount gear or as the primary disconnect ahead of a transformer. Switches do not have the fault-interrupting rating of breakers — they need an upstream fuse or breaker to clear faults. ClarkTE services all three: switchgear, switchboards, and load-break switches, with NETA-aligned acceptance and maintenance testing.