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General information on building site installations

Building site installations must meet the requirements laid down in the Heavy Current Executive Order.

The tender documentation must describe how individual contractors hold responsibility for electrical installations or parts thereof on the building site, as well as the extent of the same, e.g. the period of time over which this is to take place.
Newly installed electrical installations must be reported to the local electrical utility by an authorised electrical installer. This is applicable to both temporary and permanent installations.

If a temporary installation on the building site is retained for more than three months, the installation must be inspected every three months by an authorised electrical installer. The owner (user) of the temporary installation is responsible for the state and maintenance of the installation.

Building power supply

Electrical cables which power main or sub switchboards must be protected from damage. They can, for example, be suspended, buried or protected in some other way.

To prevent injury, building power supply cables should not be laid on roads or walkways. If this is unavoidable, the cables must be protected against mechanical overload. For example, cables can be buried under the carriageway.


If the cables are buried, they must be located at a depth of at least 35 cm and be protected with conduits, U-profiles or plastic cover plates.


Cables and wires can also be suspended on masts, building elements, scaffolding, trestles or similar. In such instances, they must be secured using insulated material. If you use such suspended cables, you must ensure that they are clearly labelled and hang away from roads and walkways or are sufficiently high to prevent cranes, excavators, trucks and other work machinery from striking them.


Temporary installations must be positioned in such a way as to move as little as possible.

Flexible cables, apart from input cables (cables on electrical devices and extension cables) must as a minimum be sheathed and heavy – type H07RN-F or equivalent.

Construction switchboards

Construction switchboards must be CE-labelled and compliant with the provisions of EN 60439-4. Switchboards which do not meet this standard and are labelled with information stating this must not be used.

Construction switchboards must be secured so as not to tip over and must be positioned in such a way that they are accessible and can easily be operated. The area in front of the switchboard must be tidy.

Plugs in construction switchboards must be protected from indirect contact by means of ground fault current circuit-breakers (HFI breakers or HPFI). Plugs designed for powering other switchboards must not be connected to any other equipment. These plugs will be labelled with a warning, e.g.:

If a fuse is tripped, you must only insert a new fuse straight away. If this fuse also trips, you have to call an electrical installer. This is also applicable in the case of reclosing of automatic fuses.

It has to be possible to interrupt the power supply to the building site. Therefore, there must be lockable switches in all construction switchboards.

Appliances and tools

Appliances which are connected to installations on the building site must be protected against indirect contact.

Plugs must normally be fitted with earthing contacts which are connected to a protective wire. These plugs can be general earthed Danish plugs, earth pin plugs or industrial plugs.


This is also applicable to cable reels and similar. Here, both the plug and the socket outlet component must have earthing contacts.

You must only connect appliances to the voltage and current for which they are designed. They may be connected by inserting a plug in a socket or by means of a wired-in connection, as is the case with e.g. cranes and similar. Only authorised electrical installers may install wired-in connections.

There must be a lockable switch (repair switch) on wired-in appliances.

Plugs, sockets and extension cables must have great mechanical strength, e.g. two-coloured (red/green). Only one cable must run from a plug or extension cable.

It must not be possible to snap cables, and cables must be secured to prevent them being trapped, penetrated by sharp edges and similar.

Cable reels must be sufficiently sound, using cables which are sheathed and heavy, type H07RN-F, or equivalent wear and water resistant cables, and be fitted with protective wire and an earthing leg/contact.


Remember to unwind the entire cable from the reel, otherwise there will be a risk of the cable on the reel melting (burning together).

Enterprises must ensure that electric hand tools are inspected regularly according to the instructions of the manufacturer.

  • In general, electric hand tools (class I) must be inspected at least every two months.
  • Double-insulated tools (class II) normally have to be inspected every six months. Most professional hand tools are double-insulated.


HFI/HPFI switches are very sensitive and can also interrupt the power supply on account of moisture. Therefore, it is a good idea to ensure that collection points such as plugs, sockets and extension cables can be kept dry. Hang up the cluster, cover it or wrap it up.