Degree of service safety electrical installations largely depends on the operating conditions and the nature of the environment of the premises in which the electrical equipment is installed. Moisture, dust, caustic fumes, gases, high temperatures have a destructive effect on the insulation of electrical installations, thereby significantly worsening safety conditions.

The premises are classified according to the most high class explosiveness of the installations located in them. Aggressive, damp, dusty and similar environments not only worsen the working conditions of electrical equipment, but also increase the danger of electrical installations for people serving them. Therefore, in the Electrical Installation Rules (PUE), premises depending on the possibility of injuring people electric shock subdivided into three groups:

• with increased risk;
• especially dangerous;
• without increased risk.

Premises without increased danger- these are premises in which there are no conditions that create an "increased danger" or "special danger". Rooms without increased danger include dry, dust-free rooms with normal temperature air, insulating (for example, wooden) floors, with no or very few earthed objects. An example of premises without increased danger are ordinary living rooms, laboratories, as well as some industrial premises, including assembly shops of watch and instrument factories, located in dry, dust-free rooms with insulating floors and normal temperature.

Depending on the type technological activities indoors various categories and the possibility of electric shock to people are determined by the nature of the performance of electrical equipment used for a given environment, the types and methods of performing electrical networks.

Premises with increased danger, characterized by the presence of one of following conditions that create an increased risk:

• a) dampness ( relative humidity air for a long time exceeds 75%) or conductive dust (according to production conditions, process dust is released in such an amount that it can settle on wires, penetrate inside machines, devices, etc.);
• b) conductive floors (metal, earthen, reinforced concrete, brick, etc.);
• in) high temperature(temperature exceeds constantly or periodically (more than 1 day) +35 °C);
• d) the possibility of a person simultaneously touching the metal structures of buildings connected to the ground, technological apparatus, mechanisms, etc., on the one hand, and to the metal cases of electrical equipment, on the other.

An example of high-risk areas is stairwells various buildings with conductive floors, workshops for machining wood, even if they are located in dry, heated buildings with insulating floors, since there is always the possibility of touching the motor housing and the machine, etc. at the same time.

Majority industrial premises refer to high risk areas, i.e. they are characterized by the presence of dampness (relative humidity long time exceeds 75%) or conductive dust, conductive floors (metal, earthen, reinforced concrete, brick), high temperature (exceeding 30 ° C for a long time), as well as the possibility of a person simultaneously touching the metal structures of buildings connected to the ground, technological apparatus, mechanisms, on the one hand, and to the metal cases of electrical equipment - on the other.

Particularly dangerous premises, characterized by the presence of one of the following conditions that create a particular hazard:

• a) special dampness (relative air humidity is close to 100% - the ceiling, walls, floor and objects in the room are covered with moisture);
• b) chemically active or organic environment (aggressive vapors, gases, liquids are constantly or for a long time, deposits or mold are formed that destroy insulation and current-carrying parts of electrical equipment);
• c) simultaneously two or more conditions of increased danger.

Particularly dangerous premises are most of the industrial premises, including all machine-building and metallurgical plants, power plants and chemical plants, water pumping stations, premises batteries, electroplating shops, etc.

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Classification of electrical installations and premises

The analysis performed shows that the risk of electric shock to a person in electrical installations depends on:

1. electrical installation voltage;
2. power supply neutral mode;
3. earth fault current;
4. insulation resistance of current-carrying parts relative to the ground and grounded structures;
5. resistance of the human body;
6. resistivity soil in the zone of current spreading.

Conventionally, all electrical installations can be divided into:

1. electrical installations up to 1 kV;
2. electrical installations above 1 kV;
3. electrical installations with low voltage (not more than 42 V);
4. electrical installations with low earth fault currents ( I 500A);
5. electrical installations with high earth fault currents ( I>500A).

"Rules for the installation of electrical installations" (PUE), in relation to electrical safety measures, divides electrical installations into:

1. electrical installations with voltages above 1 kV in networks with a solidly grounded or effectively grounded neutral;
2. electrical installations with voltages above 1 kV in networks with isolated or grounded neutral through an arcing reactor or resistor;
3. electrical installations up to 1 kV in networks with dead-earthed neutral;
4. electrical installations up to 1 kV in networks with isolated neutral.

To the first category include electrical installations in networks of 220 kV and above operating with dead grounding of transformer neutrals, as well as electrical installations in networks of 110-220 kV operating with effectively grounded neutrals of transformers (for some transformers of this network, the neutrals are ungrounded, or special active ones are included in the neutrals of some transformers, reactive or non-linear resistances). Effectively grounded neutrals are used to limit earth fault currents.

To the second category include electrical installations in 3-35 kV networks operating with an isolated neutral with a relatively small capacitive earth fault current, as well as 3-35 kV electrical installations operating in the resonant grounding mode of part of the neutrals of the network elements. Earthing of neutrals through arcing reactors or resistors is used to limit earth fault currents (to compensate for capacitive earth fault currents).

The operating conditions of electrical installations also significantly affect the risk of injury. So, humidity, high temperature, caustic fumes, conductive dust change the insulation resistance of the current-carrying parts of the electrical installation. Under their influence, the resistance of a person also changes.

Regarding the risk of electric shock to persons The rooms are divided into:

Premises without increased danger, in which there are no conditions that create an increased and special danger;

Premises with increased danger, characterized by the presence of one of the following conditions:

1. heat;
2. the possibility of a person simultaneously touching the metal structures of buildings connected to the ground, technological apparatus, mechanisms, etc., on the one hand, and to the metal cases of electrical equipment (open conductive parts), on the other.

Particularly dangerous premises, are characterized by the presence of one of the following conditions:

1. special dampness;

The territory of open electrical installations in relation to the danger of electric shock to people is equated to especially dangerous premises.

Tables 3.1 and 3.2 present the classification of premises by the nature environment and the degree of danger of electric shock to people.

According to the availability of electrical equipment, the premises are divided into:

- closed electrotechnical - lockable premises in which electrical equipment is installed that does not require constant supervision. Access to these premises is allowed only to persons from among the electrical personnel for a short time (switchgear rooms up to and above 1 kV);

Electrical personnel- administrative-technical, operational, operational-repair, repair personnel organizing and carrying out installation, adjustment, maintenance, repair and management of the operating mode of electrical installations (having qualification groups II-V for electrical safety).

- electrotechnical - premises or fenced-off parts of the premises in which electrical equipment is installed that requires permanent electrical personnel (control rooms, power plant machine room, etc.);

- production - premises in which electrical equipment is available for a long time to electrotechnological personnel (workshops);

Electrotechnological personnel - personnel who, under their control, technological process the main component is Electric Energy(for example, electric welding, electrolysis, etc.), using manual electric cars, portable power tool (where two or more high group on electrical safety).

- office and household - canteens, locker rooms, service office premises, living rooms, etc.

Table 3.1. Classification of premises according to the nature of the environment

Table 3.2. Classification (according to PUE) of premises according to the degree of danger of electric shock to people

Dry rooms are rooms in which the relative humidity of the air does not exceed 60%.
Wet rooms are rooms in which vapors or condensing moisture are released only briefly in small quantities, and the relative humidity of the air is more than 60%, but does not exceed 75%.
Raw rooms are rooms where the relative humidity of the air exceeds 75% for a long time.
especially raw rooms are rooms in which the relative humidity of the air is close to 100% (the ceiling, walls, floor and objects in the room are covered with moisture).
hot rooms are rooms in which, under the influence of various thermal radiations, the temperature constantly or periodically (more than 1 day) exceeds +35 ° C (for example, rooms with dryers, drying and kilns, boiler rooms, etc.).
dusty rooms are rooms in which, according to production conditions, technological dust is released in such an amount that it can settle on wires, penetrate inside machines, apparatus, etc.
Dusty rooms are divided into rooms with conductive dust and rooms with non-conductive dust.
Premises withchemically active or organic environmentare rooms in which aggressive vapors, gases, liquids are constantly or for a long time, deposits or mold are formed that destroy the insulation and current-carrying parts of electrical equipment.
According to the risk of explosion or fire, the premises are explosive (six classes - B-l, B-la, c, g, B-II and B- II a) and flammable (four classes - P- I, P-II, P-III a, P-III ).
According to electrical safety conditions, electrical installations are divided into installations up to 1000 V and installations above 1000 V, active and inactive.

With regard to the danger of electric shock to people, there are:
1. Premises without increased danger, in which there are no conditions that create an increased or special danger.
2. Premises with increased danger, characterized by the presence in them of one of the following conditions that create an increased danger:
a) dampness or conductive dust (relative humidity exceeds 75%);
b) conductive floors (metal, earthen, reinforced concrete, brick, etc.);
c) high temperature (more than 35 °C);
d) the possibility of a person simultaneously touching the metal structures of buildings connected to the ground, technological apparatus, mechanisms, etc., on the one hand, and to the metal cases of electrical equipment, on the other.
3. Particularly dangerous premises, characterized by the presence of one of the following conditions that create a particular hazard:
a) special dampness;
b) chemically active or organic environment;
c) simultaneously two or more conditions of increased danger.
4. Territories for placement of outdoor electrical installations. With regard to the danger of electric shock to people, these territories are equated to especially dangerous premises.

Where work is connected with electricity, there is always the possibility of electric shock to a person. Impact of adverse conditions external environment aggravated by the fact that the human body is able to provide little resistance. What if indoors high humidity, then the probability of electric shock increases, since human sweat conducts it very well. There is a classification of premises according to the danger GOST provides for three classes.

Classification of premises without increased danger

In such rooms and air humidity, there is no dust, the floors are made of materials that do not conduct current (usually wood), there are no grounded objects or their number is minimized. These rooms allow you to use with a voltage of 220 volts. Classification of premises according to the danger of electric shock includes:

• rooms for the work of administrative and managerial personnel;
• computer technology centers;
• auxiliary, instrumental and control rooms.

Classification of premises with increased danger

These spaces are characterized by:

• relatively high humidity air exceeding 75%;
• temperature with a constant or periodic mark on the thermometer of 35 degrees;
• conductive dust that covers the wires and internal surfaces electrical equipment;
• conductive floors. They are made of materials such as metal, brick, reinforced concrete, or simply earth.

The room belongs to the category of increased danger if at least one of these characteristics is present. The classification of premises according to the danger of electric shock of this class applies to the production premises of enterprises associated with vehicles, zones by maintenance and repair, thermal, welding departments.

Classification of premises of special danger

They differ:

• excessive which reaches 100%, due to which condensation forms in the room;
• the presence in the room of chemical aerosols that conduct current, as well as vapors, liquids and gases, which gradually destroy the insulation and conductive parts of electrical equipment.

A room affected by mold is also considered especially dangerous, since it, along with chemical gases, can also destroy the insulating layer. It is unacceptable for moisture to penetrate the building from the outside. A constant downpour will make it especially wet, and, therefore, extremely dangerous. A room that is characterized by two or more conditions at the same time is also considered especially dangerous. This classification of premises according to the danger of electric shock refers to:

• warehouses in which fuels and lubricants are stored and;
• battery and painting departments;
• washing and steaming chambers.

On the territory with the placement of outdoor electrical installations on it, the classification of premises according to the danger of electric shock applies. contain the basic requirements that electrical installations must comply with. The area may or may not be fenced. It is necessary that the electrical equipment has reinforced insulation.

In cases of electrical shock to the object, it is necessary to influence the flame (when ignited) by any fire extinguishing means. This is ordinary water. But here, too, there are drawbacks. Since water has a high electrical conductivity, it should not be used in case of ignition of electrical installations with high voltage. In the case of extinguishing oil products, the situation is complicated by the fact that they continue to burn on its surface. In these cases, chemical foam and powder formulations are used.

In order to prevent electrocution, it is always better to minimize the risk, namely:

1. Apply protective fences around electrical hazardous areas. Such protection will help to avoid close contact with live objects and, as a result, protect against electric shock.
2. The use of an interlock will help to avoid an accident if the current is restricted due to equipment failure.
3. To avoid emergencies use portable grounding conductors, especially if work is carried out on open areas where there is direct contact with the ground. The earthing switch will direct the electricity, in case of an overvoltage situation, to the ground.
4. Comply with technical safety measures using protective insulation, etc.).

AT normative documents a special group highlighted the work carried out in adverse conditions. For example, in boilers, apparatuses, vessels made of metal, where the ability to move the operator and exit from closed space. In this regard, there is a classification of premises according to the danger of electric shock. Therefore, the requirements for conditions that ensure safety are higher than in rooms with a special danger.

Electrical safety issues in production, this is only a part of all activities and requirements industrial safety. Compliance with the requirements of numerous instructions and rules, ensuring safe conditions labor is assigned by the RF Labor Code to the employer. He is also responsible. Its measure depends on the severity of the consequences of violations or non-compliance with the requirements of industrial safety and labor protection. The head of the enterprise, especially if it is a large one, appoints employees responsible for fulfilling the requirements of OT, fire and electrical safety.

Regulations

The rules for the installation of electrical installations (PUE) apply to all electrical installations under construction and reconstruction of alternating and direct current voltage of 750 kV and are mandatory, regardless of industry affiliation and form of ownership. The new, 7th edition is constantly updated as the materials are processed and agreed with the interested departments and approved by the ministry.

Nevertheless, experts argue that the publication does not cover the entire scope of the necessary changes, and probably in the near future the next updated edition of the PUE will be released.

labor protection requirements and fire safety when working with electrical installations, they also change.

Categories of premises for electrical safety, PUE

In accordance with the rules of the device - electrical installations is a set of technological electrical equipment of machines and apparatus, together with the structures in which they are installed, intended for generation or transmission, transformation and redistribution, conversion into other types of energy. Are divided into:

1. Outdoor (open). Located in an open area not protected from atmospheric influences.
2. Closed (internal). Located in buildings protecting them from atmospheric influences.

Electrical premises - various structures, buildings or fenced off parts of the premises in which electrical equipment is located with access only for qualified personnel engaged in maintenance. All these electrical safety rooms are divided into 4 categories:

1. Premises without increased danger.
2. High risk areas.
3. Particularly dangerous.
4. Territories where open electrical installations are installed, where electric shock to people is possible, are classified as especially dangerous premises.

1 category

The PUE states that these are premises in which there are no conditions for the occurrence of increased or special danger. What are these premises?

Premises without increased danger are ordinary residential or office buildings. Enterprises social sphere kindergartens, schools, hospitals and so on. Basic requirements for the 1st category:

• Dry - 60% and wet rooms air humidity in which should not exceed 75%.
• Working supply and exhaust ventilation. There must be no conductive dust and chemical compounds in the air.
• The ambient temperature does not exceed +35°C.
• The floor covering must be made of materials that do not conduct electricity.

Some industries and workshops can also be included in this category, but the above conditions must be met. Labor protection requirements for employees are limited to introductory briefing, and twice a year briefing at the workplace.

Specialists with the 3rd tolerance group up to 1000 volts are allowed to service electrical installations. Responsible for the electrical equipment is appointed from the composition of the engineering and technical staff with the 4th group.

The current classification of premises for electrical safety of the PUE to the second category includes those that meet the following criteria:

• Damp rooms. Humidity over 75%
• Conductive dust may be present in the air.
• Workshops with a high content of chemical compounds in the air.
• The floors are made of materials capable of conducting electricity (metal, earth, reinforced concrete, brick, etc.).
• Rooms with high temperatures.
• The ability to simultaneously touch the machine or other equipment on the one hand and the metal parts (cases) of electrical equipment or open conductive parts on the other.

The list of enterprises and workshops that fall into this category is very large. Almost all enterprises, with the exception of especially dangerous ones, fall into this category.

It is mandatory to carry out occupational health and safety measures. In specialties related to work in hazardous and hazardous industries, it is carried out extra education with certification and admission of employees. Evaluation of workplaces is carried out.

At enterprises in without fail an electrical examination of the premises for electrical safety is carried out. Based on the conclusions of the examination, a category is assigned and a special sign (tablet) is posted at the entrance, on which the class of the room for electrical safety is registered.

Only qualified specialists who have been trained and have an access group in accordance with the requirements of labor protection when servicing electrical installations are allowed to service.

Particularly dangerous in terms of electrical safety are those in which there is at least one of the following factors:

• Particularly raw. Air humidity 100%. Walls and equipment are covered with moisture falling out in the form of condensate.
• Premises with an active chemical or organic environment that occurs indoors during a work shift. This environment destroys parts of electrical installations and wire insulation.
• If two factors related to conditions of increased danger occur simultaneously.

This category of electrical safety premises has special requirements for the equipment and materials used. More frequent maintenance and repairs are planned. Only qualified and trained to work in certain conditions staff. Labor protection, as a rule, classifies such production as harmful.

The category of especially dangerous includes outdoor switchgear - open switchgears. Transformer substations, distribution units consisting of huge amount electrical equipment. Located in an open area and fenced. These are areas closed to unauthorized entry, where special industry-specific requirements for labor protection and qualifications of workers apply.

All premises certified for electrical safety must be marked with signs informing employees and representatives of regulatory authorities about the category of danger behind the doors.

Conclusion

Establishing the class of premises for electrical safety is a mandatory procedure, but in itself does not change anything. The statistics of electrical injuries and accidents suggests that this is the result not so much of poor knowledge of the PUE and labor protection requirements, but of electrical installations malfunctioning. Their inconsistencies with the PUE.

In addition to the risks of electrical injury, it should be borne in mind that electrical installations very often cause fires. The attention of the Ministry of Emergency Situations to electrical equipment and networks, always regardless of the category of premises, is increased.

SES and Rospotrebnadzor are serious about inspections of enterprises. These bodies are interested in the working conditions of workers. And they will not pass by the premises with electrical installations.

The special attention of the state indicates the seriousness of the problems in this area. Expect tougher requirements and responsibilities. Emergence of new rules and regulations.

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