BS EN IEC 61439: what a panel builder has to verify

If you build low-voltage switchboards, panelboards or motor control centres to BS EN IEC 61439-2, verification comes in two parts. Design verification proves the design once, on a representative sample. Routine verification checks every assembly you build. If you build on a verified assembly system, its manufacturer is responsible for the basic design verification.¹ Routine verification is yours, and so is anything you changed from the verified design.

The summary here draws on the guide published by BEAMA, the UK trade association for the electrical sector.² It is an explanation and does not replace the standard, so work from your own copy of the standard for clause-level requirements.

Which part of the standard applies

BS EN IEC 61439 is a series. Part 1 holds the general rules. It is not a product standard, and its clauses apply only when the relevant product part calls them up. Part 2 sets the requirements for power switchgear and controlgear assemblies, known as PSC assemblies, rated up to 1,000 V AC or 1,500 V DC. BEAMA names low-voltage switchboards, panelboards and motor control centres as products that should conform to it.²

PSC assemblies are intended mainly for industrial, commercial and similar uses, where operation by ordinary persons is not intended.²

If your control panel is part of a machine, the picture changes. Typically it should comply with BS EN 60204-1, with some clauses of BS EN 61439-1 and -2 considered where relevant. The 61439 series is not designated under the Supply of Machinery (Safety) Regulations, so it gives no presumption of conformity with them, while BS EN 60204-1 is.³ Settle which applies early, with whoever is responsible for compliance.

Design verification: done once

Design verification confirms that a design complies with the standard. It is performed once on a representative sample, in clean and new condition if it is verified by test. The manufacturer developing the reference design is responsible for showing that it conforms.²

There are three ways to verify a characteristic, and the standard limits which ones are allowed for each:

• Testing, on a representative sample where the test clause allows it.
• Comparison with a reference design, meaning a design that has already been verified by test.
• Assessment, a documented check by calculation or design rules.

Where anything other than a test is used, margins are included so that the specified performance is still achieved.² The table shows how the options differ for eight of the characteristics. BEAMA's guide lists them all.²

These options have limits. BEAMA describes temperature-rise verification by calculation for assemblies with a rated current up to 1,600 A. It also says that a short-circuit test is not required for assemblies on a supply with a prospective short-circuit current of no more than 10 kA RMS or 17 kA cut-off, although switching devices and components must still comply.² Read the conditions before you rely on either.

What this means for a panel builder

BEAMA notes that verification by exhaustive testing is expensive and time consuming,² which is why panel builders commonly start from a verified assembly system. What the system manufacturer verified only reaches as far as the verified design. BEAMA is clear that bespoke elements not covered by earlier verification must themselves go through design verification, which can take place at any stage of manufacture, including during routine verification, and must be done by people who understand the original design parameters.²

This is the part of the job that deserves attention at the quoting stage. Moving a device, changing a busbar, adding ventilation or swapping a component for an alternative can each take you outside what was verified. List every deviation and decide how each one will be verified before you commit to a price or a date.

The short-circuit test also carries a warning: such tests can affect an assembly's performance, and they should not be performed on an assembly that will then go into service.²

Routine verification: done on every assembly

Routine verification is the responsibility of the manufacturer completing the assembly. It is normally done at that manufacturer's premises, and it exists to detect faults in materials and workmanship and to confirm that the assembly works.² It is non-destructive, and it does not need to repeat tests already carried out on the components.

BEAMA lists what it covers, as applicable to the assembly:²

1. Degree of protection of enclosures
2. Clearances and creepage distances
3. Protection against electric shock and continuity of protective circuits
4. Incorporation of built-in components
5. Internal electrical circuits and connections
6. Terminals for external conductors
7. Mechanical operation
8. Dielectric properties
9. Wiring, operational performance and function

Two practical points follow from the guide. Modular designs that ship in sections do not have to be fully coupled for the routine test. And routine verification is not meant to be repeated on site, but that does not remove the installer's obligation to confirm a correct installation and test under BS 7671. Before that testing is done, the effect of the tests on voltage-sensitive components should be established.²

If you buy wiring in rather than making it, the workmanship your routine verification relies on starts with your supplier. The questions in the guide to wire harness manufacturing are a useful starting point, and the comparison of harnesses and cable assemblies sets out what to put in the specification.

What the customer has to tell you

Verification only makes sense against a defined duty. The specifier should provide the environment and the system design requirements in which the assembly will operate. For anything not supplied, the standard's default arrangements apply, and where there is no default, the manufacturer supplies its standard configuration.² So if the customer says nothing, the defaults apply. Write down which ones you have assumed.

The legal side in Great Britain

The standard is not itself the law, but BEAMA calls conformance to designated standards the most readily and widely used way of showing that you meet it. It points to three sets of regulations:²

• The Electrical Equipment (Safety) Regulations 2016, which require electrical equipment to be safe in its intended use.
• The Electricity at Work Regulations 1989, which among other things require systems to be constructed so as to prevent danger, so far as is reasonably practicable, and bar equipment from use where its strength and capability may be exceeded in a way that gives rise to danger.
• The Electromagnetic Compatibility Regulations 2016.

Under the Electrical Equipment (Safety) and EMC Regulations, a designated standard gives a presumption of conformity. Using one is voluntary under most UK product regulations.⁴ For the Electricity at Work Regulations, BEAMA goes no further than saying that verified designs assist in demonstrating compliance.²

Check two points that have moved

BEAMA's guide dates from July 2023, and two of its statements need checking against current sources.

Marking. The guide says CE marking could continue to be used in Great Britain until the end of 2024. Current government guidance says the UK continues to recognise the CE marking alongside or in place of UKCA for the Great Britain market, under the Product Safety and Metrology (Amendment) Regulations 2024.⁴ Confirm which applies to your product.

Editions. The guide says BS EN 61439-2

was due to be withdrawn in May 2024 and that the 2021 edition had not yet been designated.² The government's consolidated list for low-voltage equipment, version 13 of 5 September 2025, still names EN 61439-2 and not the 2021 edition.⁵ Check the list again before you cite an edition on a declaration of conformity, as it may have changed.

Notes

1. Machinebuilding.net, Changing industry standards: BS EN 61439 one year on. Trade article. ↩

2. BEAMA, Guide to Verification: Low-voltage Power Switchgear and Controlgear Assemblies in accordance with BS EN IEC 61439-2

   , July 2023. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷

3. D. Coulson and P. Skyrme, Safe Machine, Should you use BS EN 61439 or BS EN 60204 for machine control panels?, Industrial Technology, 13 May 2024. ↩

4. GOV.UK, Placing UKCA or CE marked products on the market in Great Britain. Last updated 21 August 2026, accessed November 2026. ↩ ↩²

5. GOV.UK, Designated standards: low voltage, consolidated list version 13. Accessed November 2026. ↩