IEC 61439 is an important reference for low-voltage switchgear and controlgear assemblies, but writing “IEC 61439” in a BOQ is not enough to define a complete assembly. An EPC contractor or project buyer should also state the electrical system, installation conditions, short-circuit requirement, internal separation, enclosure protection and documentation expected at handover.
Which parts of IEC 61439 apply?
IEC 61439-1 contains general rules covering definitions, service conditions, construction requirements, technical characteristics and verification requirements. It is used together with the relevant product part. For power switchgear and controlgear assemblies, IEC 61439-2 provides the specific requirements. The applicable edition and project specification should be confirmed before quotation.
A model name such as MNS, GCS or GCK does not by itself prove that the final assembly satisfies every project requirement. Compliance relates to the completed configuration and its verification basis.
Ten points EPC buyers should define
1. Assembly application
State whether the equipment is for main distribution, sub-distribution, motor control, capacitor compensation or another duty. Include the required operating philosophy and system interfaces.
2. System voltage and frequency
Confirm rated operational voltage, insulation requirements, frequency, number of phases, earthing arrangement and auxiliary control voltage.
3. Rated current and feeder schedule
Provide the incoming rating, busbar rating, outgoing feeder ratings, diversity assumptions and future spare requirements. A feeder schedule is more useful than a cabinet quantity alone.
4. Short-circuit requirement
State the prospective short-circuit level at the installation point and the required withstand duration. Protection settings and device coordination should match the approved system study where available.
5. Installation environment
Define indoor or outdoor installation, ambient temperature, altitude, humidity, pollution, dust, ventilation and any corrosive or special site conditions.
6. Enclosure and IP rating
Specify the required degree of protection and whether it applies with doors closed, during normal operation or under another stated condition. Room layout and heat dissipation must be considered together.
7. Internal separation and access
State the required form of internal separation, front or rear access, fixed or withdrawable functional units, cable compartment arrangement and maintenance expectations.
8. Cable entry and interfaces
Confirm top or bottom entry, cable sizes and quantities, gland plate requirements, busduct interfaces, control terminals and communication connections.
9. Component requirements
List approved or preferred breaker, contactor, relay, meter and control component brands. Substitutions should be reviewed because they can affect layout, ratings and documentation.
10. Verification and handover documents
Define the required drawings, component schedules, routine verification records, test documentation, manuals, packing details and witness or factory acceptance arrangements. Do not assume that every project requires the same document set.
Design verification and routine verification are different
Design verification addresses whether the assembly design meets the applicable construction and performance requirements. Routine verification is performed on completed assemblies to identify faults in materials and workmanship and to confirm the manufactured equipment against the approved design. Buyers should state what evidence and records must be submitted with the order.
Documents to include with the RFQ
- Single-line diagram and system data
- BOQ, feeder schedule and cabinet list
- Required IEC standard and project specification
- Short-circuit study or stated fault level
- Room layout, cable entry and dimensional restrictions
- Approved component list
- Inspection, testing and document requirements
- Destination country, quantity and delivery schedule
Related switchgear selection guidance
Review the MNS, GCS and GCK comparison for configuration priorities, or browse the complete electrical equipment range. Final selection should follow the project SLD and specification rather than a model name alone.
Frequently asked questions
Is IEC 61439-1 enough for a power switchgear assembly?
IEC 61439-1 contains general rules and is applied together with the relevant product part. For power switchgear and controlgear assemblies, IEC 61439-2 is the specific part normally reviewed.
Does an IEC model name guarantee project compliance?
No. The completed assembly, its ratings, construction, components, installation conditions and verification basis must match the applicable standard and approved project documents.
What should be sent before requesting a price?
Send the SLD, feeder schedule, ratings, fault level, enclosure requirement, component preference, project specification, quantity and destination. Missing points can then be listed during engineering review.
Start with the actual project requirements
Zejiefu prepares project-based configurations from the submitted drawings and technical scope. Any standards, verification records and deliverables must be confirmed for the specific order.
Reference: IEC 61439-1:2020 official publication page and IEC TR 61439-0:2022 guidance page.
Prepare a coordinated RFQ package
Use the SLD and BOQ preparation guide to align feeder references, ratings, installation requirements and document revisions before submitting the enquiry.
BOQ and RFQ are different documents
For procurement terminology and document responsibilities, read BOQ vs RFQ for electrical switchgear projects.
Coordinate the APFC capacitor bank data
Where reactive-power compensation is included in the package, provide the existing and target power factor, load profile, required kVAr and harmonic information. Review the APFC capacitor-bank selection inputs before issuing the RFQ.