What can this exact breaker carry?
Read its rated-current definition with the product standard, poles, terminals, temperature, mounting, and ordered configuration.
Air circuit breaker selection
Rated Current of an Air Circuit Breaker (ACB): In, Frame Size and Ir
The rated current of an ACB is a device capability for an exact configuration under stated conditions. It is not the frame label, trip setting, fault rating, or complete switchboard capacity. A defensible selection checks all of those items separately.
Frame is a platformAF or a frame number does not prove the configured continuous-current capability.
In and Iu need contextThe exact meaning comes from the governing standard, nameplate, order code, and OEM data.
Ir is a trip settingIt cannot increase the capacity of contacts, terminals, busbars, cables, or the assembly.
Fault duty is separateIcu, Ics, Icw, and Icm answer different short-circuit questions.
Direct answer
Rated current is only one layer of the selection
Start with the load and current path, then verify the exact breaker configuration, protection settings, fault duty, and assembled switchboard.
When should it respond?
The sensor or rating plug and long-time, short-time, instantaneous, or ground-fault settings control protection behavior where provided.
What must the whole current path carry?
The source, ACB, busbar, conductors, joints, terminals, enclosure, and downstream equipment each impose a limit.
What happens under maximum and minimum faults?
Maximum current tests interruption and withstand; minimum current tests whether the selected protection can act in the required time.
Safety boundary: ACBs are used where shock, arc-flash, mechanical, and stored-energy hazards can be severe. This page supports specification only. Qualified and authorized personnel must follow the adopted rules, approved studies, site electrical-safety program, and exact OEM instructions for all racking, testing, settings, commissioning, inspection, and maintenance. Before exposed work, identify every source, de-energize, lock and tag as required, release stored energy, and verify absence of voltage and backfeed with suitable test equipment.
Decode the nameplate and data sheet
Use the electrical glossaryFive labels that answer different questions
The abbreviation “ACB” is an industry product-family term, not a complete standard classification. IEC 60947-2:2024 no longer classifies circuit breakers by interrupting medium. The exact marking, certificate, and product category control.
Mechanical platform
A frame designation identifies a breaker platform and its physical design envelope. One frame can support several continuous-current configurations, trip units, terminals, poles, and fault ratings.
Do not order by frame number alone.Configured current capability
In IEC data, Iu is the rated uninterrupted current: the current assigned by the manufacturer that the equipment can carry in uninterrupted duty under stated conditions. Some product documents instead use In for a breaker or trip-unit current reference.
Keep the symbol with the OEM definition.Trip-unit current reference
On electronic platforms, a sensor or rating plug can establish the measuring range and current reference used by protection functions. Its purpose and limits are family-specific.
It does not upgrade the breaker frame.Long-time pickup setting
Ir defines the long-time overload pickup where that trip unit provides the function. It is selected within the allowed range from a protection and coordination study.
It is a setting, not physical ampacity.Short-circuit performance
Icu, Ics, Icw, and Icm describe separate breaking, service, withstand, and making duties under stated IEC conditions.
Never substitute a continuous-current label.| Term | What it can tell you | What it does not prove | Evidence to request |
|---|---|---|---|
| Frame / AF | Product platform and a design ceiling used in a named family. | The ordered continuous current, sensor, Ir, terminals, poles, or fault rating. | Exact family, frame, catalog number, dimension drawing, fixed/drawout form, and nameplate. |
| Iu | IEC rated uninterrupted current under the product's stated conditions. | The finished assembly rating, field ambient result, protection setting, or fault interruption. | IEC data sheet, declared conditions, connection option, poles, terminal data, and assembly verification. |
| In | A rated-current reference defined by the exact breaker or electronic trip architecture. | One universal meaning across ABB, Schneider, Siemens, UL, IEC, or legacy products. | OEM manual section that defines In for the ordered breaker, sensor, rating plug, and trip unit. |
| Ir | Long-time pickup setting for overload protection where provided. | Extra capacity for contacts, conductors, busbars, joints, or enclosure. | Approved load, conductor, fault, and coordination study plus signed settings record. |
| Installed current | The usable result after the exact breaker, connections, environment, and assembly are evaluated. | A number that can be copied from a generic table or another manufacturer's curve. | OEM application data and IEC 61439 or North American assembly evidence for the complete configuration. |
Interpretation rule: if two current values happen to be equal, that does not make the symbols interchangeable. Quote the symbol, its definition, exact catalog number, reference conditions, and approved range. See what an air circuit breaker is for the broader operating principle and the key parts inside a circuit breaker for component terminology.
System-level selection
Rated current belongs inside the complete current path
The installed design must not exceed any applicable breaker, conductor, terminal, busbar, connection, assembly-verification, or service-condition limit. A breaker certificate cannot certify the transformer, busbar, switchboard, cable, joints, or downstream equipment around it.
Transformer, generator, UPS, or inverter
Defines normal current, source impedance, harmonics, inrush response, and maximum and minimum fault contributions in each mode.
Cables, busway, and joints
Conductor material, insulation, arrangement, terminals, ambient, grouping, and connection quality control the usable current.
Exact configured breaker
Frame, Iu/In, poles, fixed or drawout construction, contacts, terminals, sensor, trip unit, and accessories must be frozen.
Busbar and enclosure
Temperature rise, ventilation, loaded sections, terminal geometry, spacing, fault duty, and verification belong to the complete assembly.
Outgoing conductor system
Its installed ampacity and withstand must remain protected by the actual trip settings and source modes.
Demand and operating duty
Maximum demand, continuous duty, diversity, cycling, motor or transformer inrush, harmonics, and future growth form the design basis.
I ≈ S × 1,000
÷ (√3 × VLL)
÷ (√3 × VLL)
Use only as a preliminary balanced three-phase planning relationship. Here, S is apparent power in kVA and VLL is line-to-line voltage. If the input is real power, power factor matters and, when P is output power, efficiency can also matter. Review the single-phase and three-phase power guide before applying the correct system relationship.
This expression does not apply demand, diversity, continuous-duty requirements, harmonics, motor or transformer inrush, alternate sources, conductor ampacity, switchboard verification, or protection coordination. It cannot select an ACB by itself. For product-family decisions, use the protection selection guide.
Breaker rating versus assembly rating
A “2,000 A ACB” may not be a 2,000 A installed path
Think in three layers. First is the catalog or nameplate rating for the selected device under defined conditions. Second is the breaker as installed with its real terminals, conductor arrangement, ambient, altitude, and local heat. Third is the verified current capability of the completed switchboard. The installed result must satisfy all three.
IEC 60947-2 covers the circuit breaker. IEC 61439-1 and the applicable assembly part—often IEC 61439-2 for power switchgear and controlgear assemblies—address the complete assembly. In North America, a UL 1066 low-voltage power circuit breaker can be part of UL 1558 switchgear, while UL 489 breakers and UL 891 switchboards follow different product routes. Similar appearance does not make these categories interchangeable.
No universal derating percentage exists. Use the exact OEM application tables and the switchboard's verification. Do not copy a temperature or altitude curve across brands, frames, terminal arrangements, or standards.
For switchboard and project support, see solutions for panel builders and switchgear, control-cabinet wiring components, and the electrical panel monitoring solution.
Installed-current review
Open the broader ACB selection guideSix conditions that can change the usable result
These are engineering inputs, not automatic percentage deductions. The exact data and assembly verification decide whether a correction is required.
Ambient and internal enclosure heat
Room temperature, adjacent loaded sections, busbar heating, electronics, ventilation, and solar or process heat can create a local environment different from the site weather.
Evidence: OEM temperature data plus assembly temperature-rise verification.Cooling and dielectric conditions
Air density changes heat removal and dielectric performance. Apply only the exact product and assembly guidance for the installation altitude.
Evidence: catalog limits, correction data, and project insulation coordination.Terminals, stabs, and conductor layout
Fixed versus drawout construction, rear or front connections, terminal geometry, conductor quantity, joint preparation, torque, and bend space affect the thermal path.
Evidence: ordered connection option and assembly drawings.Actual RMS current and losses
Nonlinear loads can increase RMS current, neutral loading, eddy-current loss, and heat. “Harmonics” is not one generic breaker derating factor.
Evidence: power-quality study, conductor/bus design, and OEM guidance.Utility, generator, UPS, or inverter
Source changes can alter maximum demand, overload behavior, frequency, waveform, and both maximum and minimum fault current.
Evidence: study every credible normal, tie, island, and emergency state.Enclosure and simultaneous loading
Cabinet size, partitioning, ventilation, bus layout, loaded devices, and diversity are evaluated as a complete arrangement, not inferred from the breaker's label.
Evidence: the exact assembly design verification or listing.North American boundary: do not turn the familiar 80%/100%-rated breaker discussion into a global ACB rule. It applies only within the relevant UL 489 marking, installation, and code conditions. UL 1066 low-voltage power circuit breakers and IEC 60947-2 products follow their own declared application requirements.
Continuous current is not fault duty
Keep every short-circuit value with its conditions
At minimum, record voltage, frequency, poles, current nature, duration where relevant, source mode, protection settings, and the governing standard. For AC values, keep the declared prospective/RMS Icu, Ics, and Icw duties separate from the prospective peak Icm. Never compare IEC and UL/ANSI labels as synonyms.
Ultimate breaking capacity
The IEC rated ultimate short-circuit breaking capacity at stated conditions. It does not mean “one operation and discard” as a universal maintenance rule.
Compare at the actual Ue.Service breaking capacity
The IEC rated service short-circuit breaking capacity under its defined test sequence. It does not authorize automatic return to service after a real fault.
Follow the OEM post-fault procedure.Short-time withstand current
An RMS short-time current for a stated duration under declared conditions. The time value is part of the rating and matters when intentional delay is used for selectivity.
Record both current and duration.Short-circuit making capacity
A peak current making capability under stated conditions. It is not an RMS breaking value and must not be entered into a study as if it were Icu or Icw.
Keep peak and RMS values separate.Interruption and withstand input
Calculate the highest credible fault duty for utility, ties, parallel sources, generator contribution, and motor contribution where applicable.
Verify breaker and assembly duty.Protection-sensitivity input
At the remote end or on a weak generator, UPS, or inverter source, current may be too low to reach an expected pickup within the required time.
Check the exact time-current behavior.Fault-study rule: a higher ACB continuous-current rating is not evidence of higher fault capability, and Icw does not prove selectivity. A larger frame is not inherently safer or less safe. Verify the exact upstream and downstream devices, Ue, sensors or rating plugs, settings and tolerances, instantaneous override, zone-selective interlocking where used, selectivity limit, backup-protection conditions, conductors, assembly, and real source duty. Back-up (cascading) protection and selectivity are different claims; verify each separately against the manufacturer's applicable tables or an approved engineering study.
Standards route
Review SENTOP standards supportSeparate IEC evidence from North American evidence
A model can have more than one certification route, but every rating must remain attached to its own standard, test conditions, voltage, construction, and exact catalog number.
Circuit breaker plus verified assembly
IEC 60947-2:2024 covers low-voltage circuit breakers intended for installation and operation by instructed or skilled persons. Its rating language includes Iu, Icu, Ics, Icw, and Icm where declared.
- Keep the exact device declaration and product-family conditions.
- Use IEC 61439-1 plus the applicable assembly part, commonly IEC 61439-2 for power switchgear and controlgear assemblies.
- Confirm temperature rise, busbars, terminals, simultaneous loading, short-circuit duty, clearances, enclosure, and the complete verified configuration.
Product category controls the terminology
First determine whether the device is a UL 1066 low-voltage AC/DC power circuit breaker, a UL 489 molded-case or insulated-case circuit breaker, or another certified product category.
- Do not relabel IEC Icu/Ics/Icw/Icm as UL interrupting or short-time ratings.
- UL 1066 devices are commonly applied in UL 1558 low-voltage power circuit-breaker switchgear; UL 489 breakers can appear in equipment such as UL 891 switchboards.
- IEEE C37.13 supplies another low-voltage AC power-circuit-breaker framework. Read the exact nameplate, listing/certification record, and assembly label.
Category check: “air circuit breaker,” “power breaker,” “insulated-case breaker,” and “molded-case breaker” are not interchangeable purchase descriptions. Compare the exact certificate, product category, nameplate, and assembly application. See how ACBs and MCCBs differ and the molded-case circuit breaker range.
Seven-step workflow
Send Your ACB RequirementsTurn a load requirement into a documented ACB configuration
This workflow identifies selection evidence. Qualified engineers must complete the load, fault, conductor, protection, and assembly studies before settings are issued or changed.
Define the electrical system
Record Ue, frequency, phases, poles, earthing arrangement, neutral treatment, breaker role, source one-line, and every utility, generator, tie, UPS, or inverter state.
Output: approved one-line and operating matrix.Establish the load basis
Use approved demand, diversity, continuous duty, load cycling, motors, transformers, nonlinear loads, power quality, and justified expansion—not a generic safety multiplier.
Output: design-current schedule with assumptions.Check the entire current path
Compare the proposed breaker with incoming conductors, busbar, terminals, stabs, enclosure, outgoing feeders, and downstream equipment.
Output: documented limits and approved interfaces for every link.Apply installation conditions
Use product-specific ambient, altitude, connection, ventilation, grouping, harmonic, and environment information; then confirm the assembly verification.
Output: documented installed-current basis.Calculate maximum and minimum faults
Evaluate every credible source mode and real voltage. Keep RMS and peak values, durations, protective devices, and study cases distinct.
Output: fault-duty table at the ACB location.Coordinate the protection
Select permitted long-time, short-time, instantaneous, and ground-fault functions where applicable so conductors and equipment remain protected and selectivity goals are documented.
Output: approved study and settings schedule.Freeze the order code
Record family, frame, Iu/In, sensor/rating plug, poles, fixed/drawout construction, terminals, trip unit, accessories, control power, communication, interlocks, certificates, manuals, and spares.
Output: auditable BOM and signed submittal.For detailed field interfaces after the model is approved, use the ACB wiring-method guide. For verification and service boundaries, use the dedicated guides on testing an ACB safely and ACB maintenance. This page does not duplicate their procedures.
Application priorities
Review ACB application contextsThe same ampere label can demand a different review
These examples are decision prompts, not generic designs, mandatory settings, or product recommendations.
Normal loading plus high available fault current
Check transformer impedance, demand, bus rating, maximum fault current, selective delay, and the switchboard's short-time duty together.
Do not size from transformer kVA alone.Weak-source minimum fault current
The generator may have enough running current for the load but much lower sustained fault current than the utility. Protection must still detect and clear credible faults.
Study starting, load steps, and fault decay.Operating mode changes the path
Normal-open, normal-closed, maintenance, and parallel-source states can change current flow, fault duty, interlocks, and coordination.
Use the approved operating philosophy.Inrush and duty without generic oversizing
Evaluate starting, acceleration, cycling, overload protection, process continuity, and selectivity instead of multiplying load current by an arbitrary margin.
Protect the conductor and equipment in every state.Nonlinear current and current-limited faults
Actual RMS current, harmonics, bypass mode, inverter fault limits, waveform, frequency, and transfer states can all change the study.
Use source-manufacturer data, not utility assumptions.Physical fit is only the first check
Verify stabs, cradle, bus joints, terminals, compartment, controls, trip functions, fault ratings, assembly evidence, interlocks, spare parts, and authorized substitution.
A same-frame replacement may still be incompatible.Eight common mistakes
What to reject before the quote reaches approval
Each mistake hides a different missing input. Mark it “confirm before approval” rather than filling the gap with an assumption.
“Supply one 2,000 AF breaker”
The current configuration, sensor, trip unit, poles, terminals, mounting, fault duty, accessories, and standard route remain unknown.
Treating Iu, In, sensor In, and Ir as one value
Identical numbers can still describe different functions. Require the exact OEM definitions and permitted combination.
Raising Ir to stop nuisance operation
Find the cause and repeat the protection study. Ir cannot upgrade the hardware or downstream ampacity.
Quoting Icu at a different Ue
Fault ratings can vary with operating voltage and construction. Compare the exact declared value at the real system voltage.
Checking Icu but ignoring Ics, Icw, Icm, and time
Breaking, service, short-time withstand, and making duties are separate, and the assembly has its own fault requirements.
Applying one temperature or altitude percentage
Use only the exact breaker and verified assembly guidance for that environment and connection arrangement.
Ignoring generator, UPS, or inverter modes
Maximum utility fault current and minimum alternate-source fault current test different parts of the protection design.
Using a breaker certificate as panel approval
The completed switchboard needs its own temperature-rise, bus, terminal, enclosure, fault, construction, and market evidence.
Settings, testing, and change control
Ir belongs to an approved protection process
A permissible Ir range is not an invitation to choose a value at the front panel. The selected long-time pickup must protect the actual conductors and equipment, coordinate with upstream and downstream devices, and remain valid under normal, tie, generator, UPS, inverter, and maintenance configurations.
The settings package should identify the breaker and trip-unit firmware or revision, sensor/rating plug, long-time, short-time, instantaneous, and ground-fault parameters where applicable, study revision, responsible engineer, approval date, test method, commissioning results, and controlled as-left record. A communication-system display is useful, but it does not replace the local protection behavior or the signed settings baseline.
Do not adjust settings to cure unexplained trips. Investigate overload, inrush, harmonics, weak-source response, incorrect configuration, loose or hot connections, sensor or wiring faults, and coordination first. Any field change requires authorization, documentation, and verification under the project safety and quality plan.
ACB rated-current RFQ checklist
Ask the supplier to verify one complete configuration instead of guessing from “2,000 A ACB.” Attach the one-line, load schedule, fault study, settings philosophy, switchboard drawings, and destination-market requirements.
Role: incomer, feeder, bus tie, generator interface, bypass, retrofit, or spare. Include criticality, service continuity, operating philosophy, and expected lifecycle.
Ue, frequency, phases, poles, neutral, earthing system, source ratings and impedances, one-line, available modes, and destination country.
Design current, maximum demand, continuous duty, diversity, load profile, motors/transformers, power factor, harmonics, cycling, and justified growth.
Manufacturer/family, frame, Iu/In, sensor or rating plug, poles, fixed/drawout form, terminal orientation, connection kit, and mechanical accessories.
Trip-unit model, L/S/I/G functions where required, approved setting responsibility, control voltage, closing/shunt releases, undervoltage release, auxiliary contacts, interlocks, and communication.
Maximum and minimum fault current by source mode, actual Ue, X/R or power-factor basis where relevant, Icu/Ics/Icw/Icm or applicable North American ratings, delays, and study reference.
Ambient, altitude, enclosure, ventilation, busbar, cable/busway, terminal geometry, conductor material/quantity, compartment, IP/Type environment, corrosion, vibration, and maintenance access.
Exact standards/listing, certificate or file, data sheet revision, drawings, curves, assembly evidence, manuals, test records, settings template, spare parts, quantity, delivery, labeling, and OEM packaging.
Browse the SENTOP product catalogue, review OEM/ODM project support, or send the complete data package through SENTOP contact support. Component matching does not replace the project's electrical design, protection study, assembly verification, approval, or commissioning.
Continue the research
Use each guide for its own decision
This rated-current page stays focused on current labels and complete-path approval. The resources below own the adjacent tasks.
Choose the most suitable ACB family
Compare application role, construction, poles, trip functions, environment, maintenance, and supply evidence after the current basis is understood.
Open the ACB selection guideExplore the main ACB types
Separate fixed and drawout construction, application context, and product-family terminology without using the type name as a rating.
Compare ACB typesReview model-specific wiring boundaries
Move to field interfaces only after the exact breaker, control voltage, accessories, drawings, and safety procedure are approved.
Open the wiring-method guidePlan testing and maintenance safely
Testing, inspection, racking, lubrication, and settings verification need qualified personnel, OEM limits, site risk controls, and records.
Open the ACB testing guide
Thermal observations are evidence—not ratings
Abnormal heat needs a qualified investigation
Temperature rise can come from overload, harmonics, poor joints, damaged contacts, incorrect torque, corrosion, insufficient ventilation, nearby heat sources, or a configuration outside its verified conditions. A thermal image shows temperature distribution at one operating moment; it cannot prove ACB rated current or identify the cause by itself.
Any energized diagnostic work must be permitted by the governing electrical-safety rules and the employer's authorized procedure, and performed only by qualified persons using required shock and arc-flash controls. Exposed inspection, cleaning, tightening, or disassembly must follow the de-energization, lockout/tagout, stored-energy, and absence-of-voltage requirements for the site and equipment.
Document the complete context: load, phase current, ambient, comparable phases, enclosure state, time, instrument settings, inspection location, alarms, maintenance history, connection records, and the exact product data. Replace or service damaged equipment only as the manufacturer directs.
Frequently asked questions
ACB rated-current questions
These answers support specification. The exact nameplate, certificate, OEM documentation, adopted rules, studies, and verified assembly control the project.
What is the rated current of an ACB?
It is a continuous-current capability assigned to a particular circuit-breaker configuration under stated conditions. Depending on the product and standard, the label can use Iu, In, or another convention. It does not independently establish the completed switchboard's thermal capacity, the trip-unit setting, or short-circuit performance.
Is ACB frame size the same as ACB rated current?
No. A frame is a product-platform designation and can support more than one current configuration, trip unit, sensor or rating plug, pole arrangement, terminal option, and fault rating. Specify the exact catalog number and complete configuration rather than relying on a frame value alone.
What is the difference between In and Ir in an ACB?
In is a rated-current reference defined by the exact product documentation; in some electronic systems it is established by a sensor or rating plug. Ir is a long-time overload pickup setting where that trip unit provides it. Because notation and ranges are OEM-specific, use the nameplate and trip-unit manual for the ordered configuration.
Can I increase Ir to get more capacity from an ACB?
No. A permissible Ir change only changes an overload-protection setting. It does not increase the thermal capability of the breaker frame, contacts, terminals, busbar, cable, enclosure, source, or switchboard assembly. Any setting change needs a qualified protection review, authorization, verification, and an updated settings record.
Is a higher-rated ACB always safer or better?
No. A larger frame is not inherently safer or less safe. Suitability depends on the configured continuous current, sensor, trip settings, conductors, terminals, assembly, maximum and minimum fault duty, coordination, and application. A mismatch can leave conductors or equipment inadequately protected even when the headline ampere value is larger.
How do temperature and altitude affect ACB rated current?
They can affect thermal and dielectric conditions, together with enclosure ventilation, connection arrangement, adjacent heat, and simultaneous loading. Use the exact product family's application guidance and the completed switchboard's verified capability. Do not copy a correction percentage between manufacturers or configurations.
Is Icu the same as ACB rated current?
No. Icu is an IEC rated ultimate short-circuit breaking capacity at stated conditions, including operating voltage. It is not a continuous-current rating. Also keep Ics, Icw with its duration, Icm as a peak value, and the assembly's short-circuit evidence separate. North American ratings use different product categories and terminology.
What information should I give an ACB supplier before ordering?
Provide the application role, one-line diagram, voltage, frequency, earthing and poles, load and source modes, required current configuration, installation environment, switchboard details, maximum and minimum fault-study data, protection and coordination requirements, terminals, fixed or drawout construction, accessories, destination-market standards, and required drawings, curves, certificates, test records, manuals, settings documents, spares, quantity, and delivery needs.
Primary technical sources
Use the current edition and exact product record
Standards define product and assembly frameworks. Manufacturer documents illustrate only the named family. Neither is a rating for another model.
IEC 60947-2:2024Low-voltage circuit-breaker product standard; Edition 6.Official IEC page
IEC 61439-1:2020General rules for low-voltage switchgear and controlgear assemblies.Official IEC page
IEC 61439-2:2020Power switchgear and controlgear assembly requirements.Official IEC page
UL 1066Low-voltage AC and DC power circuit breakers used in enclosures.Official UL Standards page
UL 489Molded-case circuit breakers, molded-case switches, and circuit-breaker enclosures.Official UL Standards page
IEEE C37.13-2024Low-voltage AC power circuit breakers used in enclosures.Official IEEE page
UL 1558Metal-enclosed low-voltage power circuit-breaker switchgear.Official UL Standards page
UL 891Switchboards; complete-equipment evidence remains separate from the installed breaker.Official UL Standards page
ABB SACE Tmax XT7 Ekip Touch instructionsFamily-specific example of In, rating plug, protection thresholds, and tolerances.Official ABB document
Schneider MicroLogic X setting guidanceFamily-specific protection-setting boundary and study inputs.Official Schneider guidance
UL circuit-breaker marking guideNorth American marking and application context, including continuous-load markings.Official UL guide
OSHA 29 CFR 1910.333U.S. workplace requirements for electrical safety-related work practices; other jurisdictions use their own rules.Official OSHA text
Configure the breaker and switchboard together
Do not send an RFQ that says only “2,000 A ACB”
Send the one-line, load schedule, source modes, current-path details, fault and coordination study, environment, switchboard configuration, required standards, quantity, and destination. SENTOP can use that package for component matching and an auditable quotation.
Final electrical design, protection settings, assembly verification, installation, testing, commissioning, and approval remain the responsibility of qualified project parties.
