IEC 61472:2004 ED2

Live working - Minimum approach distances for a.c. systems in the voltage range 72,5 kV to 800 kV - A method of calculation

Publication date:   Jul 15, 2004

General information

99.60 Withdrawal effective   Apr 11, 2013


TC 78 Live working

International Standard

13.260   Protection against electric shock. Live working | 29.260.99   Other electrical equipment for working in special conditions | 29.240.20   Power transmission and distribution lines



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Describes a method for calculating the minimum approach distances for live working, at maximum voltages between 72,5 kV and 800 kV. This standard addresses system overvoltages, and the working air distances between parts and/or workers at different potentials.

The required withstand voltage and minimum approach distances calculated by the method described in this standard are evaluated taking into consideration the following:

- workers are trained for, and skilled in, working in the live working zone;

- the anticipated overvoltages do not exceed the value selected for the determination of the required minimum approach distance;

- transient overvoltages are the determining overvoltages;

- tool insulation has no continuous film of moisture present on the surface;

- no lightning is seen or heard within 10 km of the work site;

- allowance is made for the effect of conducting components of tools;

- the effect of altitude on the electric strength is taken into consideration.

For conditions other than the above, the evaluation of the minimum approach distances may require specific data, derived by other calculation or obtained from additional laboratory investigations on the actual situation.

The contents of the corrigenda of May 2005 and November 2006 have been included in this copy.

Life cycle


IEC 61472:1998 ED1


IEC 61472:2004 ED2
99.60 Withdrawal effective
Apr 11, 2013


Corrected by
IEC 61472:2004/COR1:2005 ED2

Corrected by
IEC 61472:2004/COR2:2006 ED2


IEC 61472:2013 ED3