Safety measures of electric installation maintenance (all-Union State Standard 12.1.019-79).

Safety of electric installation maintenance must be provided by:

- electric installations construction;

- technical methods and protective means;

- organizational and technical arrangements.

The technical methods and protective means, that provide electric safety, are ought to set taking into account:

a) nominal voltage, current type and frequency used by electro-installations;

b) power supply method (from stationary network of the electric power, from autonomous power source, etc);

c) neutral mode (middle point) of electric power source (isolated or earthed neutral);

d) execution type (stationary, movable, portable);

e) conditions of external environment:

- specially dangerous workplaces,

- workplace of raised danger,

- workplace without raised danger,

- in the open air;

f) possibilities for voltage taking down from current conducting parts, on which or not far from which a work ought to be fulfilled;

g) disposition of possible human touch to current curcuit elements;

- monophase (unipolar) touch,

- dysphasic (bipolar) touch,

- touch to metallic non-conducting parts, that appeared under voltage;

h) approach possibilities to current conducting parts, that are found under voltage, on distance lesser from acceptable or being borrowed inside zone of current spreading out;

j) type of works: mounting, setting up, testing, electric installations maintenance, realization of works inside zone of electric installations disposition, in that number in zone of air lines of electricity transmission.

To provide the safety of electric installation maintenance in due course to employ separately or in combination one of one following technical methods and methods:

- protective earthing;

- zero setting;

- smoothing of potentials;

- small voltage;

- electric networks division;

- protective cutting off;

- insulation of current conducting parts (working, additional, reinforced, double);

- compensation of shorting currents on earth;

- protective devices;

- preventive signaling, blocking, safety signs;

- protective means and preservative adaptation.

For guaranteeing of works safety in operating electro-installations the following organizational arrangements are ought to be fulfilled:

- appointing of persons, responsible for organization and performance of works;

- legalization of order or instructions on work performance;

- realization of admittance on works performance;

- supervision of works performance;

- legalization of work finishing, interruptions in work, transposition on other work places.

For safety provision at work performance with voltage taking down in operating electro-installations or not far from them following technical arrangements are ought to be fulfilled:

- plant (parts of plant) cutting off from electric power source;

- mechanical locking of the drives, commuting vehicles cutting off, taking down of safety devices, disconnection of supplying lines and other arrangements providing impossibility of false voltage serve to work place;

- installation of safety signs and putting in enclosure of current conducting parts which are remaining under voltage, to which is possible to touch or to approach on inadmissible distance during the work;

- applying of grounding (putting on of earth knives or applying of portable grounding);

- enclosure of work place and installing of attributed safety signs.

2. To describe, how object is linked up (by means of plug connectors (ШР) or, if this is a sub-block, by means of which connectors namely, what that provides from safety point of view), that is designed for supplying circuits or distributive shields.

3. To indicate, what kind of to barrier, screens, housing are employed, where the elements and schemes details are placed, that are found under high voltage, what safety arrangements are offered in project.

4. To indicate, what types of connecting wires are chosen, why they are namely selected; to indicate, why and what type of insulation is employed: working, double, reinforced; how the wires are laid: in plaits, in pipes, in walls, in interstice, under the floor, etc.; how they are set to port, what type of clamps are used and what this gives from point of view of safety at object maintenance.

5. To show that contemporary elements and details, operation amplifiers are employed or not in scheme; small voltage (lesser than 42 V) is employed or not, as major measure of electric installation maintenance safety, and in which circuits; what the advantages are reached by that from point of view of safety or object maintenance.

6. To consider, how the questions of preventive signaling and its vividness are solved, preventing blocking, wire ends marking, which are linked, how are fulfilled mounting regulations that exclude grinding, shorting.

It’s necessary to solve the questions with choice of materials for dielectric stoutness, heat-resistant, humidity resistance, corrosive and mechanical stability.

Questions of ergonomics, technical aesthetics, blowing in superscription on objects covers must be considered, which explain, remind, warn, inhibit.

For projects, in which the test benches are performed, special attention must be paid with respect to ergonomics.

In given subdivision it is necessary also to take results of computation or of protective earthing, or illumination. And to substantiate a necessity of this computation. The examples of typical tasks are followed.