IEC 62271-200 does not award one overall “type-tested switchgear” badge; it defines an assembly and a set of ratings, construction/accessibility attributes and classifications that apply only within documented configurations and test boundaries. LSC, partition class and IAC answer different questions and must never be substituted for one another.
This article explains the current IEC 62271-200:2021 plus Amendment 1:2024 framework for prefabricated AC metal-enclosed switchgear above 1 kV and up to and including 52 kV. It turns the designations into procurement, operation and evidence checks without pretending that a classification authorizes work on energized equipment.
Executive conclusions
- IEC 62271-200 applies to indoor/outdoor prefabricated metal-enclosed AC assemblies above 1 kV through 52 kV, at service frequencies up to 60 Hz; assemblies may contain air- and/or fluid-filled compartments.
- Use IEC 62271-1 common specifications together with IEC 62271-200 and the relevant component standards.
- Ratings—voltage, insulation level, current and fault duty—describe electrical capability. LSC, partition class and IAC are classifications with different purposes.
- LSC describes which other high-voltage compartments/functional units are intended to remain energized when an accessible high-voltage compartment is opened.
- LSC2B generally preserves more of the same functional unit than LSC2A, but neither means maintenance can proceed without isolation, proving dead, earthing and an approved safety procedure.
- PM means the partitions/shutters separating an open accessible compartment from high-voltage parts remaining live are metal and earthed under the classification rules; PI means the arrangement does not meet PM.
- IAC states internal-arc type-test performance for an accessibility type, classified sides, current and duration under a specified installation/test arrangement.
- IAC is optional unless specified, is not an IEEE 1584 incident-energy result, and does not make door-open work arc-safe.
- Every panel type, compartment and lineup end/duct/room arrangement needs applicability evidence; one flagship panel test cannot be assumed to cover all variants.
- Procurement should use a classification schedule and report-to-offer matrix, not a single “IEC compliant” line.
1. Scope and edition control
- alternating current assemblies;
- rated voltage above 1 kV and up to and including 52 kV;
- service frequency up to and including 60 Hz;
- indoor or outdoor installation;
- prefabricated, metal-enclosed switchgear/controlgear;
- air-insulated and/or fluid-filled compartments;
- functional units using devices governed by their own relevant standards.
The third edition was published in 2021 and replaced the 2011 edition. Amendment 1 was published in 2024; the consolidated designation is IEC 62271-200:2021+AMD1:2024. Freeze that exact baseline, including applicable IEC 62271-1 edition, in the specification. “Latest IEC at delivery” is not a reproducible test basis.
2. Assembly standard versus component standard
| Object | Typical IEC document | Evidence question |
|---|---|---|
| Common HV switchgear requirements | IEC 62271-1 | Service conditions, common ratings/design/tests |
| Metal-enclosed MV assembly | IEC 62271-200 | Assembly construction, compartments, LSC/partition/IAC and assembly tests |
| AC circuit-breaker | IEC 62271-100 | Making/breaking/TRV/endurance of offered breaker |
| Disconnector/earthing switch | IEC 62271-102 | Isolating, indication, interlock and making duties |
| Switch/load-break switch | IEC 62271-103 | Load/fault-related switching duties |
| Switch-fuse combination | IEC 62271-105 | Combined device/fuse performance |
| CT/VT/LPIT | IEC 61869 series | Accuracy, insulation and transient requirements |
A breaker report does not prove the assembly temperature rise, short-time current path or IAC. An assembly report does not excuse missing breaker duty. Require both levels and verify their interfaces.
3. Ratings are not classifications
| Ratings/capabilities | Classifications/attributes |
|---|---|
| Rated voltage and insulation levels | Loss of service continuity (LSC) |
| Rated frequency | Partition class PM or PI |
| Rated continuous current | Internal arc classification (IAC), when assigned |
| Rated short-time withstand current and duration | Accessibility type and classified sides for IAC |
| Rated peak withstand current | Compartment accessibility control |
| Switching-device making/breaking duty | IP degree and other enclosure properties |
A panel can be LSC2B-PM yet have an inadequate short-time current rating. It can be electrically rated but have no IAC classification. Write each requirement separately.
4. Functional unit and compartment mapping
- identify each incomer, feeder, coupler, riser, metering and auxiliary functional unit;
- identify busbar, switching-device, connection/cable and VT/auxiliary high-voltage compartments;
- show fixed, removable and withdrawable parts and their service/test/disconnected positions;
- show shutters, partitions, bushings, pressure-relief zones and gas compartments;
- state which compartments are intended to be accessible and under what control;
- state what must be isolated/earth when each accessible compartment is opened;
- map every claimed classification to this physical arrangement.
Classification is easier to audit with a colored cross-section and an access-state table. Product marketing drawings without live/dead boundaries are insufficient.
5. High-voltage compartment accessibility
- Interlock-controlled accessible: design interlocks control access in the intended operating sequence.
- Procedure-based accessible: access depends on an approved procedure and locking provisions rather than a complete interlock sequence.
- Tool-based accessible: opening/removal requires tools under the defined design intent.
- Non-accessible: not intended to be opened by the user; sealed/welded arrangements and manufacturer rules apply.
These labels do not decide whether a person may enter. The employer’s safe isolation, proving-dead, earthing and permit system remains controlling. Tool removal is not, by itself, an electrical safety condition.
6. What LSC actually measures
Loss of service continuity is a user-oriented category defining the possibility of keeping other high-voltage compartments and/or functional units energized when an accessible high-voltage compartment is opened. It is based on the intended access arrangement, not a general reliability percentage or mean time between failures.
| Category | Operational consequence in principle | What it does not promise |
|---|---|---|
| LSC1 | Opening an accessible HV compartment can require other functional units or a larger portion of the assembly to be de-energized | Unsafe/obsolete; it can be appropriate where continuity is not required |
| LSC2 | Other functional units can remain in service under defined access conditions | Every compartment in the same functional unit remains live |
| LSC2A | Other functional units can remain energized, but access generally requires de-energizing the other HV compartments of the affected functional unit as defined | Cables/bus can always remain energized for every access |
| LSC2B | Other functional units and at least part of the affected functional unit can remain energized under the defined compartment access | Work is permitted without the safety procedure or that all panel types are LSC2B |
The current edition includes a more precise LSC description and an explanatory flowchart in Annex D. Apply that normative logic to each intended accessible compartment; do not rely only on the simplified table above.
7. LSC classification workflow
- Is a high-voltage compartment intended to be accessible? If none is, LSC may not apply as expected.
- Select the specific compartment and intended access state.
- Identify which functional units must be de-energized.
- Identify which other HV compartments in the same functional unit must be de-energized.
- Determine the category using IEC 62271-200 definitions/flowchart.
- Repeat for cable, switching-device, VT and other accessible compartments.
- Record main-circuit isolation/earthing and removable-part positions.
- Verify the offered panel variant and tested construction support the claim.
8. Partition class PM and PI
Partition class addresses the nature of the barrier between an open accessible high-voltage compartment and other high-voltage parts intended to remain live.
- PM (partition of metal): the relevant partitions and shutters are metallic and connected to earth in accordance with the standard’s requirements.
- PI (partition of insulating material): at least one relevant partition/shutter arrangement does not meet PM and uses insulation in the separation concept.
PM can provide an earthed screen and clear separation concept; PI can enable compact or specific device designs. PM is not automatically “safer” in every failure mode, and PI is not deficient if correctly designed/tested. Verify dielectric strength, earth continuity, shutters, partial-discharge behavior, ageing, contamination and the intended accessible state.
9. LSC and partition class are separate
- LSC asks what may remain energized during defined access.
- PM/PI asks what separates the open accessible compartment from HV parts remaining live.
- A product designation can therefore pair LSC and partition class, for example LSC2B-PM.
- Neither designation states internal-arc performance.
- Neither replaces circuit diagrams, isolation points, interlock matrix or operating instructions.
10. Internal arc classification (IAC)
IAC is assigned when the assembly has passed the IEC 62271-200 internal-arc test for stated conditions. The designation contains accessibility, classified sides where applicable, arc current and arc duration. Example format:
IAC A FLR, 25 kA, 1 s
- A: accessibility restricted to authorized personnel.
- B: unrestricted accessibility, including general public.
- C: accessibility restricted by installation out of reach above a public area; use the exact current-edition provisions/report for applicable equipment.
- F/L/R: front, lateral and rear classified sides for A/B arrangements.
- Current: tested internal arc current, not automatically the assembly short-time withstand rating.
- Duration: tested arc duration, not a promise that protection will clear in that time.
The manufacturer defines the front. Wall-standing switchgear may be FL while free-standing arrangements may require FLR. A missing side is outside the claim unless the installation/report provides the applicable boundary.
11. What the IAC test evaluates
- behavior of correctly secured doors and covers;
- fragmentation/projection from the enclosure;
- holes/burn-through on accessible classified sides within the evaluation zone;
- ignition behavior of indicators positioned to represent exposure;
- continued effectiveness of the enclosure earthing connection;
- gas/flame/particle effects for the specified duration and test arrangement.
Use the standard’s exact five acceptance criteria. The 2021 edition introduced a one-second rule in Criterion 4 to distinguish hot gases from glowing particles as the cause of indicator ignition. A summary certificate cannot show how a marginal result was judged; review video, photographs, indicator results and the complete report.
12. IAC test boundary
- panel types/compartments and arc-initiation locations;
- lineup length, end panels and adjacent units;
- door, cover, shutter and breaker positions;
- accessibility type and F/L/R sides;
- test current, duration, voltage and neutral earthing;
- room simulation, ceiling/wall clearances and floor openings;
- duct, plenum, absorber/filter and exhaust endpoint;
- cable entry sealing, vents and pressure-relief flaps;
- indicator location/material and acceptance observations;
- modifications between tested and offered assemblies.
The third edition gives more precise treatment of protrusions and moved examples outside the IAC test from the earlier clause structure. Do not extend an IAC claim beyond the report using catalogue shorthand.
13. IAC is not arc-flash analysis
| IEC 62271-200 IAC | Arc-flash risk assessment/IEEE 1584 |
|---|---|
| Physical type test of an assembly/configuration | Calculation and task/equipment risk assessment |
| Specified current, duration, sides and installation | Arcing current, protection clearing time, geometry and working distance |
| Evaluates enclosure/indicator criteria | Predicts incident thermal energy and boundary within model scope |
| No PPE category or incident-energy value | Feeds workplace controls/labels under governing rules |
| Generally assumes specified closed/secured condition | Must assess actual task state, including open doors where applicable |
Do not apply an arbitrary “IAC reduction factor” to incident energy. Credit containment or remote operation only through the governing risk-assessment method and exact installed/tested conditions.
14. IAC current/duration selection
- calculate credible internal arc current at each bus/compartment, considering system earthing and source configuration;
- do not automatically equate three-phase bolted fault current, earth-fault current and internal arc current;
- determine total clearing time: protection, logic, trip path, breaker interruption and credible backup;
- consider low arcing current causing slower protection;
- specify a test current/duration that bounds the approved protection strategy;
- verify all sources/ties are tripped and breaker failure is addressed;
- document what happens if arc duration exceeds the tested value.
15. Room, plenum and exhaust interface
- match wall/ceiling clearances to the test report and manufacturer minimums;
- size/anchor ducts and plenums for pressure and hot-gas duty;
- do not obstruct pressure-relief flaps with cables, lighting or building services;
- route exhaust to a controlled area inaccessible during operation;
- assess fire, smoke, toxic/corrosive by-products and weather ingress;
- seal floor/cable openings as represented and maintain drainage/ventilation;
- verify lineup extensions and end covers preserve the pressure path;
- include civil interfaces in FAT/SAT/as-built inspection.
16. IP and IK are additional properties
IEC 60529 IP codes address access to hazardous parts and ingress of solid objects/water at specified enclosure boundaries. IEC 62262 IK addresses mechanical impact. Neither IP nor IK proves IAC, LSC or partition class. Specify outer enclosure, between-compartment and post-access states separately; ventilation, pressure relief, filters and field penetrations can change performance.
17. Withdrawable, removable and fixed designs
- a withdrawable breaker can support isolation/maintenance flexibility but does not automatically confer LSC2B;
- a fixed breaker with a separate disconnector can achieve a high continuity category;
- a sealed RMU can be compact/IAC but may have no user-accessible HV compartment for the same maintenance task;
- truck “test” and “disconnected” positions must match primary/secondary connection and shutter design;
- maintenance/replacement strategy should drive the construction choice, then classification verifies it.
18. Procurement classification schedule
| Field | Required project entry |
|---|---|
| Standard | IEC 62271-200:2021+AMD1:2024 and IEC 62271-1 baseline |
| Functional unit | Incomer/feeder/coupler/metering/riser/auxiliary type |
| Accessible compartments | Cable/switching device/VT/etc. and access control |
| LSC | Category per functional unit/accessible compartment |
| Partition | PM or PI and relevant barriers/shutters |
| IAC | Accessibility, sides, current, duration, each represented configuration |
| Ratings | Voltage/insulation/current/short-time duration/peak and switching duties |
| Installation | Indoor/outdoor, altitude/temperature, wall/free standing, room/duct |
| Evidence | Full report IDs, tested object, laboratory and applicability assessment |
| Operating state | Doors/covers/breaker/earth/automatic protection assumptions |
19. Report-to-offer verification
- manufacturer, factory, product family and drawing/BOM revision;
- ratings and panel/compartment dimensions;
- busbar, support, enclosure and partition materials;
- breaker/switch/earthing switch, CT/VT and cable interface;
- gas/insulation medium and pressure;
- LSC access map and PM/PI barrier construction;
- IAC panel types, arc locations, ends, classified sides and current/duration;
- room/plenum/duct/filter and exhaust geometry;
- doors, latches, vents, relief flaps and floor/cable seals;
- design changes, failures, repairs, retests and extension-of-validity rationale.
20. Operational translation
- convert LSC diagrams into approved isolation/earthing states;
- label accessible compartments and actual live boundaries;
- preserve shutters, partitions, earth bonds and pressure paths during maintenance;
- prohibit opening/operation states outside the IAC claim unless risk controlled;
- link IAC duration to protection settings and breaker timing verification;
- inspect doors, latches, relief flaps, ducts and end covers after work;
- review classification after retrofit of CTs, VTs, sensors, cables or breakers;
- train operators that classification describes design capability, not work authorization.
21. Common mistakes
- calling all IEC 62271-200 equipment “arc resistant”;
- treating LSC2B as an energized-maintenance permission;
- equating PM with IAC or PI with unsafe design;
- assigning one LSC category to every panel without compartment analysis;
- omitting IAC A/B/C, F/L/R, current or duration;
- assuming IAC current equals short-time withstand rating;
- ignoring room/duct/end-panel installation boundary;
- using an IAC certificate instead of complete report;
- crediting IAC as an IEEE 1584 energy reduction;
- assuming withdrawable automatically means LSC2B;
- mixing current 2021+AMD1:2024 claims with an unassessed 2011 report;
- modifying doors, vents, partitions or pressure paths without classification review.
Primary references
- IEC 62271-200:2021—AC metal-enclosed switchgear above 1 kV through 52 kV.
- IEC 62271-200:2021/AMD1:2024—Amendment 1.
- IEC 62271-200:2021+AMD1:2024 consolidated version.
- IEC 62271-1:2017—Common specifications and Amendment 1:2021.
- IEC 62271-100:2021+AMD1:2024—AC circuit-breakers.
- IEC 62271-102:2018+AMD1:2022—Disconnectors and earthing switches.
Safety note: LSC, PM/PI and IAC are equipment classifications. They do not replace safe isolation, proving dead, earthing, arc-flash/shock assessment, manufacturer instructions or an authorized permit-to-work system.