Building UL 508A panels in the UK for North American machines
If your machine is heading to the US or Canada, the panel has to meet UL 508A. Here is what changes from UK practice and how to plan for it.
Read the articleIf you buy, specify or build low-voltage panels in the UK, BS EN 61439 is the standard that sits behind almost all of them. It replaced the older BS EN 60439 series, and it changed the way panels are verified by making it much clearer who is responsible for what. This guide explains the parts of the standard that matter most when you’re ordering a control or power panel.
What BS EN 61439 covers
BS EN 61439 applies to low-voltage switchgear and controlgear assemblies, which in practice means panels rated up to 1000 V AC or 1500 V DC. It’s published in several parts. Part 1 sets out the general rules, and the other parts apply those rules to particular types of assembly:
- BS EN 61439-2 covers power switchgear and controlgear assemblies. Most control panels, MCCs and power panels fall under this part.
- BS EN 61439-3 covers distribution boards intended to be operated by ordinary persons.
- BS EN 61439-6 covers busbar trunking systems.
When a panel is supplied as part of a machine, BS EN 60204-1 also applies to the electrical equipment of that machine. The two standards work together rather than replacing each other.
Two roles: original manufacturer and assembly manufacturer
One of the most useful things BS EN 61439 does is separate two responsibilities that used to get blurred.
The original manufacturer is the organisation that carried out the original design of the assembly and its design verification. The assembly manufacturer is the organisation that takes responsibility for the completed assembly, builds it and carries out routine verification.
These can be the same company, but often they aren’t. Many panels are built using enclosure and switchgear systems that the system manufacturer has already design verified, and when a customer supplies the drawings, part of the design responsibility sits with them. It’s worth agreeing at the start who holds which part of the verification evidence, so nobody is left chasing it when the declaration of conformity is being signed.
Design verification
Design verification proves that a design of assembly meets the requirements of the standard. It covers characteristics such as:
- Strength of materials and parts, and the degree of protection (IP rating) of the enclosure
- Clearances and creepage distances
- Protection against electric shock and the integrity of protective circuits
- Incorporation of switching devices and components, internal circuits and terminals
- Dielectric properties
- Temperature-rise limits
- Short-circuit withstand strength
- Electromagnetic compatibility and mechanical operation
The standard allows verification by testing, by calculation or measurement, or by applying design rules, depending on the characteristic. Temperature rise is the one that most often needs real thought, especially in densely packed drive panels and MCCs where heat from drives, transformers and power supplies builds up quickly.
Routine verification: every panel, every time
Routine verification is carried out on every assembly before it leaves the workshop. It is how the assembly manufacturer confirms the panel has been built correctly and matches its verified design. It covers:
- Degree of protection of the enclosure
- Clearances and creepage distances
- Protection against electric shock and protective circuit continuity
- Built-in components fitted correctly and to specification
- Internal electrical circuits and connections, including tightness
- Terminals for external conductors
- Mechanical operation
- Dielectric properties
- Wiring, operational performance and function
At Pro Panel Build every panel goes through these checks, and you receive a signed test report and a photo record with the panel.
What you should specify
BS EN 61439 places real responsibility on the person ordering the assembly to define the conditions it will work in. The standard includes a template for this, but the key information is straightforward:
- Supply voltage, frequency and earthing system (for example TN-S or TN-C-S)
- Prospective short-circuit current at the point of supply
- Rated current of the assembly and of the main outgoing circuits
- Required IP rating and the installation environment, including ambient temperature
- Form of internal separation, where it matters (Form 1 to Form 4)
- Cable entry, access and any space or mounting constraints on site
If you’re not sure about any of these, send what you have. We’ll flag anything that needs confirming when we review your drawings, before we quote.
Marking and paperwork
Each assembly should be marked with the assembly manufacturer’s name or trademark, a type designation or identification number, a means of identifying the date of manufacture, and the part of the standard it complies with, such as BS EN 61439-2. Where the panel falls within the Electrical Equipment (Safety) Regulations 2016, it will also need UKCA marking and a declaration of conformity, or CE marking for the EU market.
How we help
We build to BS EN 61439 as standard, carry out routine verification on every panel, and supply the test report, photo record and marking your panel needs. If you’d like help pulling together design verification evidence from the enclosure and component manufacturers’ verified systems, talk to us when you send your drawings.