Our engineering manager John Meijer shares his knowledge. Every month, he discusses a different topic in the field of electrical safety. This time his blog is about NEN-standards.
Which standards can be applied?
Often people don’t know when and which standards apply. In this blog we discuss the most important standards that you must apply when designing and constructing an installation or a machine. Which standard do you apply with the medium and high voltage transformer and distributor? Below I describe five standards and explain you when to apply them.
NEN-EN-IEC 61936-1: Power installations exceeding 1 kV AC
NEN-EN-IEC 61936-1 describes how installations must be set up for voltages higher than 1000. For example, how far away from a building a high-voltage transformer must be regarding fire protection, the height at which high-voltage cables must run and how to deal with safety shields. This standard contains the general requirements for the design and installation of high-voltage electrical installations. All in systems with a nominal voltage of more than 1 kV AC and a nominal frequency up to 60 Hz. The standard ensures that these installations can function safely and properly.
NEN-EN-IEC 61914: Cable cleats for electrical installations
On the low-voltage side of the transformer, we usually have to deal with higher currents due to the lower voltage. Which means that considerable short circuit currents can occur. Therefore, the cabling between the transformer and the distributor must be installed to be able to withstand the mechanical forces released in the event of a short circuit. This means that for certain short circuit values, the cables must be installed in blocks or C-brackets with a minimum distance between them. This prevents the cables from flying through the room in the event of a short circuit. Cable diameters can then be calculated with the tables from NEN 1010.
NEN-EN-IEC 61439: Low-voltage switchgear and controlgear assemblies
When we design a low-voltage distributor, we have to take all kinds of construction requirements into account, such as dielectric properties, short circuit resistance of all power chains, electromagnetic compatibility, mechanical shock load and protection class of the enclosure. All these matters must be recorded in a technical construction file. A declaration of conformity (CE) must be issued for all measurements and tests. Distribution equipment and MCCs are covered by the Low Voltage Directive 2014/35 / EU.
NEN 1010: Electrical installations for low-voltage
When constructing fixed building installations, NEN 1010 must be applied to the design and construction of the installation and cabling. All kinds of matters are mentioned in this standard, such as calculating cable diameters and requirements set for wet zones. You will also find rules regarding the maximum number of groups behind an earth leakage circuit breaker and requirements for the way of laying cable routes.
Please note! A new version of the NEN 1010 will be released in 2021. So make sure to update your knowledge as soon as the changes will be made. I will dedicate a separate knowledge blog to this once the new version is released.
NEN-EN-IEC 60204-1: Safety of machinery – Electrical equipment of machines
NEN-EN-IEC 60204-1 is used to design a safe control cabinet for a machine or installation. We often see that this standard is not or insufficiently known, while this standard is crucial for designing a safe control installation. Most people only know the NEN 1010, which is mainly intended for fixed building installations. Safe machine controls involve a little more, which is why we must follow the NEN-EN-IEC 60204-1. In this standard, references are made to other relevant standards for specific purposes. In this standard you will find everything about requirements that are placed on control circuits, emergency stop circuits, control devices, standard wire colors and grounding of various installation parts and components.
Which standards apply to cables?
Below, I will describe two standards to help you select the correct cable:
- NEN 8012: This standard is about the selection of the cable type;
- EN 50575: This standard is about power, control and communication cables.
NEN 8012 is intended to be applied to electrical cables, including glass fiber cables, for the transport of energy, signal and data in electrical installations according to NEN 1010 in construction works. The aim is to limit the occurrence and development of fire and smoke.
EN 50575 is the standard designated by the CPR (Construction Products Regulation) that tells you which cables, in fixed electrical installations in buildings, must be classified according to cable behavior in the event of fire. For example, if a fire breaks out and the cables run near walkways, you want to prevent parts of molten cables from falling on top of people while fleeing the building. In places like this, extra requirements apply to the fire behavior of the cables.
Piece of advice: purchase the standards!
Many companies apply standards or refer to standards that they do not even own. Often, for cost reasons, old copies are being used, with the result that the latest applicable standards are not applied or are poorly applied. I myself use NEN connect. With this online portal you can view or download an x number of standards for a fixed amount per year. You will then always have the latest applicable standards.