Mattias Alkeblad
- Elcentraler
- Köpguide
- Lågspänningsställverk
- SS-EN IEC 61439
A low-voltage switchgear assembly should run for 25–30 years, and your choice of supplier determines both safety and operating costs throughout that time. Check eight things before you decide: design verification to IEC 61439, the right ratings, form of separation and arc fault safety, factory acceptance testing (FAT), documentation, experience in your industry, capacity and lead time, and service throughout the lifecycle.
This guide is written for anyone buying or specifying switchgear for an industrial facility – as a design engineer, electrical consultant, buyer or maintenance manager. The questions apply to any supplier. At the end you will find a checklist to use when requesting quotes.
1. Design verification to IEC 61439
IEC 61439-1 and -2 are the standards for low-voltage switchgear and distribution boards up to 1,000 V AC. They require the switchgear design to be verified – by testing, calculation or comparison with a tested reference design. Verification covers temperature rise, short-circuit withstand strength, dielectric properties and degree of protection, among other things.
Ask the supplier how the design verification was carried out and request the documentation. The term “type-tested” is no longer enough: it comes from the previous standard, and today the manufacturer of the finished assembly is responsible for verifying every design.
2. The right ratings for your installation
The switchgear must handle the currents and faults that can occur in your specific installation. The key values to compare between suppliers:
- Rated current (InA): how much current the assembly can carry continuously without overheating.
- Short-time withstand current (Icw) and peak withstand current (Ipk): how large a short-circuit current the assembly can withstand. The value must be at least as high as the calculated short-circuit current at the point of connection.
- Degree of protection (IP): protection against dust and water, matched to the environment.
A serious supplier asks for network data and selectivity requirements before quoting. If you only provide a power rating and get a price back, treat it as a warning sign.
3. Form of separation and arc fault safety
The form of separation (Forms 1–4 under IEC 61439-2) describes how well the parts of the assembly are separated from each other. A higher form makes it possible to work in one section while the rest stays in operation, which is essential in process industries and facilities that cannot stop.
Also ask how the supplier handles the risk of arc faults. Switchgear can be tested to IEC/TR 61641 to show that an internal arc will not injure personnel in front of the cabinet. This matters most where short-circuit currents are high.
4. Factory acceptance testing (FAT) and routine verification
Every assembly must undergo routine verification before delivery under IEC 61439. This includes checks of wiring, connections, insulation and function, among other things. Ask whether you as a customer can attend a factory acceptance test (FAT) and what the test report contains.
Faults found in the factory cost a fraction of those discovered on site. A supplier that welcomes FAT shows confidence in its own quality.
5. Complete documentation
Documentation is what you live with when the switchgear is extended, serviced or inspected ten years from now. Require the delivery to include:
- circuit diagrams and layout drawings that match what was actually built
- design verification records and routine verification reports
- EU declaration of conformity and CE marking
- a rating plate with manufacturer, ratings and standard
- component lists and operation and maintenance instructions
Also ask in what format the drawings are delivered. Editable files save a lot of time when changes are needed later.
6. Experience in your industry
Many industries have requirements beyond IEC 61439. The food and beverage and pharmaceutical industries require hygienic design and often validation to GMP and GAMP. Hazardous areas require equipment to ATEX and IECEx. Marine installations and data centres have their own requirements for classification, redundancy and availability.
Ask for reference projects from your industry, ideally with a contact person. A supplier that already knows the requirements does not need to learn them on your project.
7. Capacity and lead time
Switchgear is often on the project's critical path. Ask how the supplier plans production, what the current lead time is and what happens if the project changes late. Also check whether the supplier designs and builds in-house or outsources parts of the work.
Choose standard components from well-known manufacturers where possible. This makes spare parts easier to source throughout the lifetime of the switchgear.
8. Service and support throughout the lifecycle
Switchgear needs preventive maintenance, such as thermographic inspection and re-tightening of connections, and it is often extended or modernised during its lifetime. Ask whether the supplier has its own service staff near your site, whether it offers service agreements and modernisation, and whether it can retrofit older switchgear.
A supplier that is still there after delivery reduces the risk of long downtime when something does go wrong.
Checklist: questions for the supplier
Use these questions when requesting quotes and compare the answers side by side.
| Area | Question for the supplier |
|---|---|
| Design verification | How is the design verified to IEC 61439, and can we see the records? |
| Ratings | What rated current, Icw and IP rating does the assembly have, and how were they determined? |
| Separation and safety | Which forms of separation do you offer, and is the assembly tested for internal arc faults? |
| FAT | Can we attend the factory acceptance test, and what does the report contain? |
| Documentation | Which drawings and certificates are included, and in what format are they delivered? |
| Industry experience | Which reference projects do you have in our industry, and which special requirements have you handled? |
| Capacity | What is the current lead time, and do you build in-house? |
| Service | Do you have service staff near us, and do you offer service agreements and modernisation? |
Unsure about a term? See our glossary for explanations of standards and technical terms.
Frequently asked questions
What is the difference between low-voltage switchgear and a distribution board?
Both distribute power at low voltage and are covered by IEC 61439. Switchgear usually refers to larger main assemblies with high currents, while distribution boards also include smaller sub-distribution and final distribution boards.
Is CE marking enough?
No. CE marking shows that the manufacturer declares the requirements are met, but says nothing about ratings, form of separation or quality. Ask for the documentation behind the declaration.
How long does it take to get switchgear delivered?
It depends on size, component lead times and the supplier's workload. Ask about the current lead time early in the project, as switchgear often drives the schedule.
Can older switchgear be retrofitted instead of replaced?
Often, yes. Modernisation can increase capacity and safety at a lower cost and with shorter downtime than replacement. It requires a supplier that can verify the modified assembly to the current standard.
About Elcor
Elcor designs and manufactures low-voltage switchgear and distribution boards to IEC 61439 for industry, data centres, energy and infrastructure. Every assembly is FAT-tested and delivered with complete documentation, and Elcor offers service and modernisation throughout the lifecycle. Request a quote.