Operation, maintenance and modifications

Electrical installations, like any other parts of buildings, do not remain safe and in good condition by themselves. The condition of electrical installations shall therefore be monitored and any deficiencies discovered shall be remedied. Non-residential buildings shall undergo periodic inspections. Electrical installations of category 2 and 3 specified in the Finnish electrical safety statutes (large-scale installations and certain special premises) are subject to detailed maintenance programmes prepared in advance.  


Installation category  


Category 3

  • Networks of electricity distribution network companies 

Category  2

  • Electrical installations with parts of over 1,000 V inside or outside buildings (high-voltage subscribers) and low-voltage subscribers with capacity of over 1,600 kVA

Category 1

  • Residential buildings of more than two apartments
  • Electrical installations in non-residential buildings with main fuses or similar of over 35 A (e.g. public buildings, business premises, industrial and agricultural buildings, outdoor areas)


The modifications and extension of electrical installations is mainly subject to the rules and procedures that apply to the construction of new installations.


The possessor of an electrical installation (owner, leaseholder etc.) shall attend to and is responsible for the maintenance and safe use of the installation. E.g. in housing companies, the owner is represented by the Board and its Chairman. Residents and people working in or visiting the building are considered as users of the electrical installation.


The day-to-day maintenance of larger-scale buildings is attended to by designated building managers, who are building management companies or private individuals.


For large-scale electrical installations, an operation supervisor  with sufficient qualification shall be appointed as designated person-in-charge. The operation supervisor shall be notified to Tukes. An operation supervisor is required for high-voltage subscribers, low-voltage subscribers of over 1,600 kVA capacity and electricity distribution network companies.


Upon change of the operation supervisor, a new supervisor shall be appointed within 3 months, and an appropriate notification be submitted to Tukes. Any changes in the installation possessor shall also be notified. 


The operation supervisor's leadership covers the in-service works, e.g. in-service measures and comparable operations carried out on the installation, while the repair and maintenance of electrical installation are often outsourced to a maintenance business. You should not forget that the repair and maintenance of electrical installations are legally considered as electrical work, which may only be carried out by electrical contractors duly registered by Tukes.

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