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EN 60204: is your machine electrically safe?

EN 60204: is your machine electrically safe?

The EN 60204 standard is 130 pages long and contains 18 sections and nine annexes. Paul Laidler of TUV SUD Product Service reviews key elements.

When it comes to the electrical safety of machinery there is a significant lack of knowledge as to which standard should be applied. In many cases electricians responsible for maintaining machinery on site are being trained to the British standard BS 7671 - 'Requirements for Electrical Installations'. However, this standard is only applicable in the UK and applies to low voltage electrical installations. It covers general wiring of buildings, but largely excludes machinery.

The key standard for machinery electrical safety is EN 60204-1:2006 +A1:2009 - "Safety of machinery - Electrical equipment of machines". This has been written to cover the machinery electrical requirements of different European countries, yet a great number of electricians and in-house maintenance personnel still seem unaware of its existence. Let's look at some of the key elements.

Isolators: An isolator switch is part of an electrical circuit that will electrically isolate the connected circuits to stop an unsafe machine working. EN 60204 requires that all isolators should be lockable and attached to the machine and that they should be capable of disconnecting all electrical supplies. This means that if something should go wrong, harm to machinery operators through electric shock is minimised.

If this isn't possible, circuits must satisfy further specific requirements, which are outlined in detail within the Standard.

Enclosures: The standard also requires that electrically live parts be located inside enclosures, such as doors, lids or covers, to provide protection against a human having direct contact with them. Any enclosures should only be able to be opened under one of three conditions. Again these have a complex set of requirements, but they are outlined briefly below:

  1. A key or tool must be used to open the enclosure.
  2. Before the enclosure can be opened live parts must be automatically disconnected. For example, this can be achieved by interlocking the enclosure door with a disconnecting device.
  3. If opening with a key or a disconnection device is not possible, opening of the enclosure should only be possible when all live parts are protected against direct contact to at least IP2X or IPXXB (see standard IEC 60529), which requires that an exposed terminal cannot be touched.

It is recommended that enclosure doors are no wider than 0.9m and have vertical hinges that have an opening angle of at least 95 degrees. Any large-scale enclosures, which allow a person to fully enter machinery such as palletisers, must also provide a means of escape, such as panic bolts on the inside of doors.

Colour coding: Part 10 of EN 60204 covers 'operator interface and machine-mounted control devices'. This section includes colour coding and marking requirements for push-button actuators (a mechanism that puts the electrical shut-off process into automatic action). For example, the standard states that the colours for start/on actuators should be white, grey, black or green, with a preference for white. Under no circumstances should the colour red be used as this is reserved for emergency stop and emergency switching-off actuators.

Also, unless otherwise agreed between the machine supplier and the user (the details of which is covered in Annex B of EN 60204), machine status indicator lights must be colour coded, with each colour identifying a specific status. For example, red highlighting an emergency, hazardous situation, while green indicates normal conditions.

Documentation: Section 17 of the Standard outlines what technical documentation is required to prove compliance. This includes information relating to a machine's electrical installation, operation, and maintenance, which can be in the form of drawings, diagrams, charts, tables, and instructions.

The Standard also recognises that different levels of detail will be needed depending on the complexity of the machinery. However, there are requirements which are applicable to all documentation, no matter what the machine type. The standard states that all documentation:

  • shall be in accordance with relevant parts of IEC 61082;
  • reference designations shall be in accordance with relevant parts of IEC 61346;
  • instructions/manuals shall be in accordance with IEC 62079.
  • parts lists where provided shall be in accordance with IEC 62027, class B.

Verification: The verification process is intended to assure the conformity of a product, demonstrating that it meets the specified requirements of EN 60204. This can be done at different stages throughout the design and development lifecycle process, or at the end of it. However, we would recommend that this should be done as early as possible in the design stage and become part of the ongoing development process. It is more cost effective for faults to be identified and rectified at this stage, rather than when a final machine has been produced.

The extent of the verification that is required is made clear in the specific product standard that relates to each different type of machine. However, where there is no such dedicated standard, EN 60204 requires that it must always include:

  • verification that the electrical equipment complies with its technical documentation
  • in case of protection against indirect contact by automatic disconnection, conditions for protection by automatic disconnection shall be verified according to 18.2
  • functional tests

As appropriate to the machine type, verification may also include one or more of the following items:

  • insulation resistance test
  • voltage test
  • protection against residual voltage

While EN 60204A requires only a self-declaration against the conformance process, its complexity, coupled with the potential lethal consequences if electrical safety is incorrectly administered, means that it is not a process that machine owners can afford to get wrong.

Due to the complexity of the compliance process, best practice advice would be to work with an expert, either employed in-house or an outsourced supplier, who has the necessary in-depth knowledge of all the relevant regulatory requirements.

Safety is one of the most significant issues facing machinery owners in Europe today, and the electrical element is an essential consideration for keeping machine operators and maintenance personnel safe.

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