Why BS EN 61439 Matters for Your Control Panel Build
If you are specifying or purchasing control panels for industrial equipment in the UK, BS EN 61439 is the standard you need to understand. It replaced the older BS EN 60439 series and shifted the compliance framework from type-tested assemblies to a system based on design verification.
This matters because it changes who is responsible for proving the panel meets the standard, and how that proof is documented.
What BS EN 61439 Covers
The standard applies to low-voltage switchgear and controlgear assemblies up to 1,000V AC and 1,500V DC. For most industrial control panels, the relevant parts are:
- BS EN 61439-1: General rules and definitions applicable to all assembly types.
- BS EN 61439-2: Power switchgear and controlgear assemblies (PSC-assemblies). This covers main distribution panels.
- BS EN 61439-3: Distribution boards for use by ordinary persons (DBO).
For machine control panels specifically, BS EN 61439-2 is typically the applicable part, read alongside the machinery-specific requirements of BS EN 60204-1.
Design Verification
The key change from the old BS EN 60439 is how compliance is demonstrated. Previously, you either had a fully type-tested assembly (TTA) or a partially type-tested assembly (PTTA). The new standard replaces this with three methods of design verification:
- Testing the actual assembly.
- Calculation using validated methods.
- Design rules provided by the original manufacturer of the enclosure and components.
In practice, most panel builders use a combination of all three. Temperature rise, for example, can be verified by calculation using the methods in Annex D, provided the assembly falls within the conditions specified. Short-circuit withstand might rely on the enclosure manufacturer's tested ratings.
The point is that the panel builder must hold a design verification dossier that demonstrates compliance for every design characteristic listed in the standard. If an inspector or client asks to see it, you need to be able to produce it.
Common Compliance Issues
Thermal management. Undersized enclosures with insufficient ventilation or cooling are the most frequent issue we see. The standard requires that the temperature rise within the assembly does not exceed the rated values for the installed components. Cramming too many drives into a panel without proper thermal calculation is a common way to fail this requirement.
IP rating integrity. Cable entries, gland plates, and unused knockouts all affect the declared IP rating. A panel rated IP54 on the datasheet is not IP54 if there are open holes in the gland plate.
Wiring and clearances. Creepage and clearance distances between live parts of different phases or between live parts and earth must meet the values specified in the standard. This is straightforward to achieve in a well-laid-out panel and easy to violate in a cramped one.
Documentation. The standard requires specific information to be provided with the assembly, including a single-line diagram, component layout, and the design verification records. Missing documentation is a compliance failure, even if the panel itself is well-built.
Why It Matters
A non-compliant panel is a liability. If a fault occurs and the panel has not been built and verified to BS EN 61439, the responsibility falls squarely on whoever built it and whoever specified it. Insurance claims, HSE investigations, and machinery directive compliance all reference these standards.
We design and build panels to BS EN 61439 as standard. Every panel leaves with a full documentation pack including schematic drawings, component schedules, test certificates, and the design verification records required by the standard. It adds time to the process, but it is the only way to do it properly.