Safety clearances

Making contact or near contact with overhead lines is dangerous. Overhead electric conductors are normally bare (uninsulated) and if an object approaches too closely it is possible that a flashover will occur and an electric current flow with the likelihood of fatal or severe shock and burns to any person nearby. In order to prevent such incidents minimum safety clearance for overhead lines are prescribed.
Overhead transmission lines must conform to the specifications contained in the Electricity Safety, Quality and Continuity Regulations 2002. The minimum heights at which the conductors are strung between pylons are given for lines operating at specified voltages.  
 

Overhead lines are also constructed to conform with the Energy Networks Association’s (ENA’s) technical specifications which govern the minimum clearance to be maintained between the conductors, ground, roads, trees and objects on which a person may stand. A summary of ENA’s Technical Specification 43-8 “Overhead Line Clearances” is given in table, the application of safety clearances are illustrated in figures. The minimum clearance to ground for a 400,000 volt line is 7.6m and for a 275,000 volt line is 7.0m.  

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