IEC 62271-200: Three Codes on One Nameplate — and What “Arc-Tested” Still Won’t Do for You

If you’d rather listen than read, feel free to play the audio file below for the rest of this article.

What IEC 62271-200 Covers — and Which Edition You’re Buying To

IEC 62271-200 is the international standard for factory-assembled AC metal-enclosed switchgear and controlgear at medium voltage. Its scope is precise:

• alternating current, rated voltages above 1 kV up to and including 52 kV
• service frequencies up to and including 60 Hz
• indoor and outdoor installation
• assemblies that may include air-insulated and fluid-filled compartments

It covers fixed and withdrawable designs. It does not cover individual devices: circuit breakers sit under IEC 62271-100, disconnectors and earthing switches under IEC 62271-102, and low-voltage assemblies under the IEC 61439 series. Part 200 works alongside IEC 62271-1, the common specifications for HV switchgear; where Part 200 states a more specific rule, the product standard wins.

Which edition applies to your contract:

Edition 3.0 realigned clause numbering with IEC 62271-1:2017, moved internal arc testing of pole-mounted switchgear out to IEC 62271-214, tightened the earthing circuit requirements, reduced the mechanical interlock testing required for type tests, and introduced a 1 s rule for acceptance criterion 4, separating hot gases from glowing particles in the indicator assessment.

Check clause numbers and classification wording against the edition your contract names before approving a design. A 2011-era specification and a 2021 submittal will not line up clause for clause.

For the wider framework, see our switchgear standards guide.

Metal-Enclosed vs Metal-Clad: Why IEC Dropped the Old Terms

Metal-enclosed is the family: live parts sit behind an earthed metal enclosure. Within that family, older IEC editions sorted switchgear into metal-clad, compartmented and cubicle types, based on how the interior was divided.

IEC retired that vocabulary. The current standard describes the same properties more usefully through LSC — what stays energised during access — and partition class — what the barrier is made of. Two assemblies once both labelled “metal-clad” could differ sharply in both, which is precisely why the descriptive classifications replaced the category names.

The terms have not disappeared globally. In North America, metal-clad switchgear (IEEE C37.20.2) and metal-enclosed interrupter switchgear (IEEE C37.20.3) remain distinct, current product categories. So on an international project, “metal-clad” in a specification means one thing to an IEEE-trained engineer and something historical to an IEC one.

Write it in IEC terms: state the LSC category and partition class rather than a legacy type name, and both sides will read it the same way.

Verify: the section renders as an H3 under the scope H2, and no other section repeats the metal-clad explanation.

IAC, LSC and PC: Three Questions, Three Independent Answers

The three classifications are not a ranking. They answer different questions, and a switchgear lineup can score well on one and poorly on another.

The practical consequence is that “arc-resistant switchgear” is not a specification. A complete one declares all three together — IAC rating with faces, current and duration; LSC category; and partition class — because each covers a gap the others leave open.

For how these sit in the wider regulatory picture, see our electrical standards guide.

Internal Arc Classification: What an IAC Rating Certifies

An IAC rating means a representative assembly was subjected to a real arc fault in a laboratory and controlled the consequences in declared zones. During the test the enclosure must manage pressure rise, hot gases, burning particles and mechanical shock without creating unacceptable hazard where people are assumed to stand.

Internal arc classification is a personnel protection classification. It says nothing about interrupting capacity, which belongs to the circuit breaker, or about clearing time, which belongs to protection coordination.

Its value is that it is testable. It separates verified arc fault containment from words like “safe” or “arc-proof,” which mean whatever the brochure wants them to mean. When you compare two designs, compare the declarations, not the adjectives.

One layout note that gets missed at the specification stage: the IAC rating has to match how the room is used. Front-only operator access, rear cable access and all-round maintenance access are three different risk pictures, and the test only covers the faces that were tested.

IAC Accessibility Types A and B, and the F, L, R Faces

The accessibility type states who is assumed to be near the switchgear, and it sets how close the test indicators are mounted:

Type B is the harder test: the indicators sit closer, so the enclosure has far less room to vent safely.

The letters that follow state which faces were tested:

• F — front
• L — lateral (sides)
• R — rear

Indicators are mounted in a checkerboard pattern covering roughly 40–50% of the accessible area, up to a height of 2000 mm, with horizontal indicators at the 2000 mm level to catch gas rising toward anyone standing nearby. The test runs in a simulated room with a floor, ceiling and two perpendicular walls.

The trap: an assembly marked IAC A or IAC AF has been verified for authorized-personnel access on the front only. It is not a statement about the rear or sides. If cables are landed from the back and technicians stand there, an AF rating does not cover them. Ask for AFLR where people work on more than one face.

In hazardous areas, accessibility rules interact with ATEX and IECEx zone marking.

The Internal Arc Test for MV Switchgear: Parameters and Pass Criteria

Two declared values define the test: the prospective fault current and the arc duration — for example 25 kA for 1 s, or 31.5 kA for 1 s. Both are chosen by the manufacturer and must be stated on the nameplate alongside the accessibility type and tested faces.

Match the declared current to the prospective fault current at that point in your network, and the declared duration to the realistic clearing time of the upstream protection. A 1 s rating on a system where the upstream relay clears in 0.5 s carries margin; the same rating behind a slow backup scheme does not.

The test passes only if all five acceptance criteria hold:

1. Doors and covers stay closed. Limited deformation is accepted; opening is not.
2. No fragmentation. No parts weighing more than 60 g are ejected.
3. No holes in the accessible sides up to 2 m height.
4. Indicators do not ignite from hot gases. Edition 3.0 added a 1 s rule here to distinguish ignition by hot gases from ignition by glowing particles.
5. Earthing remains effective. The enclosure stays connected to its earthing system.

Criterion 4 is the one people picture: cotton indicators standing in for exposed skin and clothing. If they ignite, the enclosure did not manage the gas.

A full marking reads like IAC AFLR 31.5 kA 1 s — tested for authorized personnel, on front, lateral and rear faces, at 31.5 kA for one second.

Four Things an IAC Rating Does Not Give You

1. It is not a survivability rating. IAC covers what happens to people, not to equipment. After an internal arc, expect inspection and replacement of affected components. The lineup is not assumed to return to service.
2. It does not replace arc flash risk assessment or PPE. Anyone working on or near equipment that can be energised still needs a documented assessment, a safe work procedure and appropriate protection.
3. It does not guarantee fast clearing. Current transformers, relay settings, coordination and upstream source impedance are system design responsibilities. The enclosure is tested against a duration; it does not create one.
4. It does not cover untested faces or conditions. The declaration covers the accessibility type and the faces stated. Everything else is undeclared.

Enclosure ingress protection is a separate question again; see our IP55 vs NEMA 12 comparison.

Arc Detection and Mitigation: Shortening the Event, Not Replacing the Test

Incident energy scales with duration, so anything that clears an arc faster reduces the damage it does. None of it replaces an IAC rating — mitigation shortens the event, while the classification proves the enclosure handled a defined one.

Options, roughly in order of how early they act:

• Optical arc detection relays sense the light of an arc and trip in a few milliseconds, often combined with a current check to avoid false operation.
• High-speed shorting devices (arc eliminators) deliberately create a bolted three-phase fault, collapsing the arc voltage and transferring energy away from the arc within milliseconds.
• Zone-selective interlocking lets the breaker nearest the fault clear it without the upstream time delay that coordination would otherwise impose.
• Fast earthing switches achieve a similar transfer by earthing the faulted section quickly.
• Pressure relief ducts and exhaust routing do not shorten the arc; they decide where the gas goes. Route exhaust away from operator corridors, doorways and walkways, and confirm the duct arrangement matches the one that was tested.

Two cautions worth writing into the specification:

• Mitigation changes the arc duration assumption, so it must be reflected in the arc flash study, not just in the equipment order.
• Duct orientation is part of the tested configuration. An assembly arc-tested with exhaust ducted upward into a plenum is not evidence for the same lineup installed with the duct removed or redirected.

Loss of Service Continuity: How Much Stays Live While Someone Works

Loss of service continuity describes what has to be switched off when an accessible high-voltage compartment is opened. It is an availability classification, and it decides whether routine maintenance on one feeder costs you one feeder or the whole lineup.

That makes LSC a design decision, not a vendor comparison footnote. A hospital, a data centre or a continuous process plant that de-energises a busbar for a cable termination is paying for the classification it failed to specify.

Two boundaries are worth stating plainly:

• LSC proves nothing about arc containment. It describes access and continuity conditions only.
• LSC is meaningless without partitions. The category describes what may stay live; the partition class describes what physically stands between that live part and the open compartment.

Service continuity also feeds wider conformity obligations, such as the CE marking rules for control panels.

LSC2A vs LSC2B — and Where LSC1 and LSC2 Sit

All four categories describe the same moment: an accessible HV compartment is open and someone is working in it. They differ in what is still live around that person.

The dividing line between 2A and 2B is the incoming cable. Under LSC2A, working in the circuit breaker compartment means the cable to that unit must be isolated and earthed. Under LSC2B, it can stay live — which is what lets a utility or data centre work on a breaker without dropping the customer’s feed.

LSC2B is not free. It requires at least three compartments per functional unit — switching device, connection, and busbar — with verified partitioning between them. If a quotation offers LSC2B on a two-compartment design, the claim and the hardware do not agree.

LSC1 remains reasonable where the whole lineup can be taken off for maintenance without commercial consequence.

Because these categories depend on busbar separation, our article on busbar manufacturing safety gives useful background. (Existing link, kept.)

Why LSC Is Only as Good as the Partition Behind It

Higher LSC categories are claims about what stays live. Partitions are what makes those claims safe to act on.

For LSC2B, the busbar and the cable connections remain energised while a technician has a compartment open. The only thing between that technician and live MV parts is the partition or shutter — so its type, its earthing and its verification are what the category actually rests on.

This is the most common specification gap we see: LSC2B requested, partition class left blank. The vendor is then free to meet the letter of the category with whatever barrier is cheapest.

The verification logic mirrors what IEC 61439 design verification does for low-voltage assemblies.

Partition Class (PC)—Compartment Separation

Partition class defines the type of barrier between compartments inside MV switchgear. These barriers may separate busbars, cables, switching devices, and secondary systems.

The main classes are PM and PI. PM uses metallic partitions. PI uses insulating partitions. Both can support compartment separation when they meet the applicable withstand requirements.

The phrase IEC 62271-200 partition class explained is important because PC often hides inside a short nameplate code. Yet it strongly affects maintenance access and internal fault behavior.

An important limit, and one most guides skip: the standard notes that selecting a partition class does not by itself ensure protection of personnel against an internal arc occurring in an adjacent compartment. PM is not an arc rating. Arc performance is what the IAC test covers; partition class describes construction.

That is exactly why the three classifications are declared together. PM tells you the barrier is earthed metal; IAC tells you the enclosure was arc-tested; LSC tells you what was live at the time.

Most utilities and critical facilities specify PM with LSC2B, for the earthing continuity and field screening a metal barrier provides.

Compartment separation also feeds arc flash risk assessment; see our arc flash label requirements guide.

Internal Arc Classification for LV Switchboards: IEC TR 61641, Not 62271-200

IEC 62271-200 stops at 1 kV. Below that, a low-voltage switchboard built to IEC 61439 has no equivalent internal arc classification inside its own standard — and that surprises people who assume “IAC” is a universal marking.

What exists instead is IEC TR 61641, Enclosed low-voltage switchgear and controlgear assemblies — Guide for testing under conditions of arcing due to internal fault, currently Edition 3.0 (2014).

Three things follow from that, and they matter when you write or read a specification:

• It is a Technical Report, not a standard. TR documents are informative guidance, not normative requirements. An assembly is not “compliant with TR 61641” the way it is compliant with IEC 61439; it has been tested in accordance with the guide.
• It sits alongside IEC 61439, not inside it. IEC 61439 verification covers dielectric, temperature rise and short-circuit withstand. Arc testing to TR 61641 is additional evidence a manufacturer chooses to obtain.
• “IAC” on an LV panel is borrowed language. The formal accessibility-type and F/L/R classification belongs to IEC 62271-200. LV manufacturers often reuse the vocabulary; ask which document the test report cites.

The test logic is recognisable: an arc is initiated inside the assembly and the enclosure must keep doors and covers closed, contain fragments, vent pressure away from personnel, avoid burn-through, and leave indicators unignited, with earthing intact.

When you specify an arc-tested LV switchboard, ask for:

• the test report naming IEC TR 61641 and its edition
• the test current and duration, matched to your fault study and the real upstream clearing time
• the arrangement tested — arc behaviour depends on the enclosure and busbar geometry, so a report for a different configuration does not transfer
• the laboratory, and whether it is accredited for this test

Where Internal Arc Testing Is Done

Arc fault containment testing needs a high-power short-circuit laboratory: a source that can deliver tens of kA into a deliberately faulted assembly, safely and repeatably. There are relatively few in the world, and manufacturers book time at them.

The names that appear most often on MV and LV arc test reports are KEMA (the Netherlands), CESI (Italy), and other accredited high-power laboratories operating to the same test procedures.

Two practical points for buyers:

• Classification is manufacturer-declared, based on test evidence. The standard does not require third-party certification. Many buyers nonetheless ask for a report from an independent accredited laboratory, and it is reasonable to make that a tender requirement.
• Check that the report matches the equipment offered. The tested arrangement, rating and configuration must correspond to what is being supplied. An arc test on a related product line is not evidence for the panel in your order.

Type Tests, and Why the Report Matters More Than the Panel

Type tests — design tests — verify a representative design, not every unit. Manufacturers run them once per design and rely on the evidence thereafter.

That is the point buyers miss. A panel can pass every routine test on the factory floor and still depend entirely on earlier type test evidence for its ratings and classifications. Two questions belong in every technical evaluation:

• Does type test evidence exist at the declared ratings — not at a lower current or a shorter duration?
• Does it cover the configuration being supplied?

Internal arc testing is the clearest case. It is performed when the manufacturer declares an IAC rating. An assembly with no IAC declaration can be fully compliant with IEC 62271-200 and must not be specified, sold or accepted as arc-tested.

For readers working across regions, our comparison of AS/NZS 61439 requirements is useful.

The Type Test Schedule

Internal arc testing is conditional, not universal. Where no IAC rating is declared, no arc containment may be assumed.

Routine Tests: What Every Delivered Panel Gets

Routine tests are performed on every completed unit before delivery, and they confirm manufacturing quality rather than design capability.

(Keep the existing bullet list.)

These records normally form part of the Factory Acceptance Test documentation. They are not a substitute for type test evidence: a perfect routine test report says the panel was built correctly to a design whose ratings were proven elsewhere.

Routine checks vary with panel design; our overview of electrical panel types adds context.

Special Tests: What You Only Get If You Ask

Special tests are agreed between purchaser and manufacturer for conditions outside normal service assumptions: seismic qualification, extreme ambient temperature, tropical humidity, coastal corrosion exposure, additional EMC verification.

They are neither routine nor standard type tests, which means they are not in the base price. If the installation justifies them, list them in the purchase specification. A supplier quoting against a specification that is silent on special tests will price the standard verification package, and rightly so.

Special tests often include EMC work; see our guide to EMC panel requirements.

Marking and Documentation to Require at FAT

The classifications only help if they arrive on the equipment and in the file. Require, as deliverables:

• The IAC label, showing accessibility type, protected faces, arc current and duration.
• The rating nameplate: rated voltage, rated normal current, short-time withstand current with duration, rated frequency, IP and IK ratings, mass, serial number and manual reference.
• Type test reports or certified summaries at the declared ratings, for the configuration supplied, each naming the standard edition it was tested to.
• Routine test records for the delivered units.
• Operation and maintenance manuals, wiring diagrams and single-line drawings.
• A compliance checklist mapping each specified requirement to its evidence — many clients now attach one to the FAT pack, and it is the fastest way to find a gap before the equipment ships rather than after.

For equipment placed on the EU or UK market, this documentation also feeds the technical file behind the CE or UKCA declaration.

Verify: the list does not duplicate the “Documents to request in the submittal” content, if you also ran that from an earlier package.

Reading a Full Declaration: IAC AFLR 25 kA 1 s — LSC2B — PM

A complete switchgear classification should combine internal arc classification, service continuity, and partition class. This combined label helps engineers compare designs without relying on vague terms.

A typical declaration looks like this:

For example: IAC AFLR 25 kA 1 s — LSC2B — PM.

Read that declaration in three parts:

• IAC AFLR 25 kA 1 s — arc-tested for authorized-personnel access on front, lateral and rear faces, at 25 kA for one second.
• LSC2B — the busbar and the cable connections can stay energised while another accessible HV compartment is open.
• PM — the partitions and shutters in the path between an opened compartment and live parts are metallic and earthed.

Each element closes a gap the others leave. Drop one and you have a claim you cannot verify: LSC2B without a partition class, or “arc-resistant” without faces, current and duration.

Declared ratings should be read alongside pollution degree and overvoltage category assumptions.

IEC 62271-200 vs IEEE C37.20.7: Specifying Across Both Markets

Both documents address arc-resistant behaviour in metal-enclosed MV switchgear, and on an international project you will meet both. They differ in test methodology, in how accessibility is classified, and — the part that catches people — in what the markings mean.

A correction worth making explicitly, because it is widely repeated wrong: IEEE’s Type 1 and Type 2 are not equivalents of IEC’s accessibility types A and B. IEEE types describe which faces are protected; IEC’s A and B describe who is assumed to have access. The nearest IEC equivalent of IEEE’s Type 1 and Type 2 is the F versus FLR face notation.

For dual-market projects:

1. Name both documents and their editions in procurement, and state which governs where they conflict.
2. Require a separate type test certificate for each. The indicator distances and arc initiation arrangements differ, so one test campaign rarely satisfies both.
3. Check the certificates are at the same current and duration. Campaigns are often run at different values, and a lineup arc-tested at 40 kA under one document is not evidence at 31.5 kA under the other unless the report says so.
4. Check the faces match the room, whichever standard applies. IEEE Type 1 and IEC AF both mean front only.
5. Brief the end client on the marking convention. An operator trained on IEC will look for AFLR; an IEEE-trained operator will not recognise it without explanation, and the reverse is equally true.

Specifying IEC 62271-200 Switchgear: An Eight-Step Sequence

Start with the system ratings. Define rated voltage, frequency, normal current, short-time withstand current, peak withstand current, and required arc duration. These values drive insulation, thermal, and mechanical design.

Next, decide whether internal arc classification is required. The answer should come from layout, personnel access, maintenance practice, and arc flash risk assessment. Do not leave the IAC decision to a generic vendor default.

Then select LSC and PC together. For critical infrastructure, LSC2B with PM or PI often provides the right balance between maintenance access and live busbar separation.

The Ratings That Must Appear in Your Specification

Before any classification is chosen, the electrical ratings have to be fixed. These drive insulation design, thermal design and mechanical strength, and a vendor cannot engineer the lineup without them:

• Rated voltage and insulation level — rated voltage U_r, lightning impulse withstand U_p and power-frequency withstand U_d, selected from the IEC 62271-1 tables according to the system’s overvoltage exposure.
• Rated normal current for the busbar and for each functional unit.
• Short-time withstand current and duration for the main and earthing circuits, with the associated peak withstand current — for example 25 kA for 3 s.
• Internal arc parameters, if IAC is required: current, duration, accessibility type and tested faces — for example 31.5 kA for 1 s, type A, faces FLR.
• Nameplate content: the IAC code, U_r, I_k with its duration, rated frequency, IP and IK ratings, mass, serial number and manual reference.

Note that the short-time withstand duration and the arc duration are different numbers for different purposes. A 25 kA 3 s withstand rating says nothing about arc containment, and a 31.5 kA 1 s IAC rating says nothing about thermal withstand. Specifications that quote one and assume the other are a recurring source of dispute at FAT.

A practical sequence works well:

1. Define rated voltage within the 1 kV to 52 kV range.
2. Define Ik, Ip, and short-circuit duration.
3. Decide whether IAC is required.
4. Select accessibility category and tested faces.
5. Select LSC category based on outage tolerance.
6. Select PM or PI partition class.
7. Check type test evidence at the declared ratings.
8. Confirm routine test documentation for delivered panels.
9. Name the edition — Edition 3.0 (2021), Amendment 1 (2024) or consolidated Edition 3.1 — so the submittal and the review use the same clause numbering.

IEC classification is normally manufacturer-declared based on test evidence. However, many buyers prefer reports from independent laboratories such as KEMA, CESI, VEIKI, or equivalent accredited test facilities.

Classification under IEC 62271-200 is manufacturer-declared on the basis of test evidence; the standard does not mandate third-party certification. Many buyers require reports from an independent accredited high-power laboratory, and that requirement belongs in the tender rather than in a later argument.

For enclosure protection alongside these classifications, see our IP vs NEMA and IK comparison.

Conclusion: Declarations Beat Adjectives

IEC 62271-200 earns its place by replacing words with declarations. “Safe switchgear” and “arc-proof panel” survive any amount of scrutiny because they mean nothing. IAC AFLR 25 kA 1 s — LSC2B — PM does not: every element can be traced to a test report.

Four habits make that work on a real project:

• Specify all three classifications together. LSC2B without a partition class is an unbacked claim.
• Match the declaration to the room. Tested faces must cover the faces people work on.
• Ask for type test evidence at the declared ratings, for the configuration being supplied.
• Name the edition. 2011, 2021, or 3.1 with Amendment 1 — they do not share clause numbering.

And keep the boundary clear: above 1 kV, IEC 62271-200 governs. Below it, arc testing follows the guidance in IEC TR 61641, which is a technical report rather than a standard.

For the complete standards landscape, revisit our core switchgear standards guide.

FAQs about IEC 62271-200