Work in electrical installations with voltage up to 1000 V

4.5. In electrical installations with voltages up to 1000 V, when working under voltage, it is necessary to:

relieve voltage from other live parts located near the workplace that are energized, which may be accidentally touched, or protect them;

work in dielectric galoshes or standing on an insulating stand or on a rubber dielectric carpet;

use an insulated tool (screwdrivers must have an insulated shaft) or use dielectric gloves.

It is not allowed to work in clothes with short or rolled up sleeves, or to use hacksaws, files, or metal meters.

4.6. It is not allowed to work in electrical installations in a bent position if, when straightened, the distance to live parts is less than the distance specified in Table No. 1.

When working near unprotected live parts, it is not allowed to be positioned so that these parts are behind the worker or on both sides of him.

4.7. It is not allowed to touch insulators or insulating parts of live equipment without using electrical protective equipment.

4.8. In crossing spans in outdoor switchgear and on overhead lines, when replacing wires (cables) and related insulators and fittings located below live wires, ropes made of vegetable or synthetic fibers. The ropes should be thrown in two places - on both sides of the intersection, securing their ends to anchors and structures. Lifting the wire (cable) should be done slowly and smoothly.

4.9. Work in the outdoor switchgear on wires (cables) and related insulators, fittings, located above wires, and energized cables must be carried out in accordance with the PPR approved by the head of the organization or separate unit. The PPR must provide measures to prevent the lowering of wires (cables) and to protect against induced voltage. It is not allowed to replace wires (cables) during this work without removing the voltage from the crossed wires.

4.10. Workers should remember that after the voltage at the electrical installation has disappeared, it can be reapplied without warning.

4.11. Work in unlit places is not allowed. The illumination of work areas, workplaces, passages and approaches to them must be uniform, without the glare of lighting devices on workers.

Mandatory requirements for protective equipment

During operation, protective equipment may lose the properties that ensure they perform their assigned tasks. To prevent any accidents, some products must undergo periodic testing and inspection, while others must undergo inspection only. All procedures are recorded in the appropriate logs, and information about suitability is recorded after testing on the protective equipment itself.

Before starting work, the responsible person must check the suitability of the insulating tool or product. And in case:

expired date;
lack of information about tests;
presence of damages exceeding those established by the rules;

withdraws such funds for repairs and unscheduled inspections.

What current is considered unsafe?

As a rule, the first sensations occur when exposed to a current of 1-1.5 mA. This value is considered a threshold. A further increase leads to involuntary contractions of the muscular system, accompanied by painful sensations.

After the level of 12 to 15 mA, the muscular system cannot be controlled. In some cases, because of this, a person caught under voltage is not able to free himself (for example, unclench his fist with a clamped wire). The current, starting from the specified point, is considered “not releasing”. Its further increase causes convulsive contractions of the heart, and a value of 100 mA leads to death.

Table of current threshold values:

Voltage	Sensible (mA)	Non-releasing (mA)	Fatal fibrillation (mA)
Variable (50 Hz)	1,0-1,5	12,0-15,0	100,0
Permanent	6,0	60,0	300,0

Please note that the table contains approximate data, since it depends on many factors, including the physical and psychological state of the person.
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Electrical protective equipment used in work

All protective devices, according to their ability to protect a person from the harmful effects of current, are divided into basic and additional means. So, when working in devices up to 1 kV, the same gloves will act as the main one, but in distribution networks above 1 kV, they will act as an additional one. Because alone they are not able to completely eliminate leakage currents or may be subject to breakdown. But the dielectric mat in all cases is exclusively an additional tool.

Look, the tables below show the division of protective equipment according to voltage class.

Table 1. Basic electrical protective equipment for working in electrical installations:

Up to 1000 V inclusive	Over 1000 V
Insulating rods	Insulating rods of all types
Insulating pliers	Insulating pliers
Clamp meter	Clamp meter
Voltage indicators	Voltage indicators
Dielectric gloves	Devices for creating safe working conditions when carrying out tests and measurements in electrical installations (voltage indicators for phasing, cable damage indicators, etc.)
Tool with insulating coating

Table 2. Additional electrical protective equipment for working in electrical installations:

Up to 1000 V inclusive	Over 1000 V
Dielectric shoes	Dielectric gloves
Dielectric carpets	Dielectric shoes
Insulating pads Insulating pads	Dielectric carpets Insulating pads
Insulating hoods	Insulating pads
Voltage alarms	Insulating hoods
Protective fences (boards, screens)	Bars for transfer and potential leveling
Portable grounding	Voltage alarms
Safety posters and signs	Protective fences (boards, screens)
Other remedies	Portable grounding
	Safety posters and signs
	Other remedies

Electric Shock Hazard

Electric shock can cause shock and loss of consciousness, as well as apnea. When receiving an electric shock, a person suddenly falls unconscious, clenching their hands tightly. Most often, the clenched hand contains an electrical wire. There may be deep burn wounds where the body comes into contact with the current. The degree of damage depends on the magnitude of the voltage and current, its duration and the path of flow.

Danger from electrical appliances

Important! Electric shock causes extensive and deep burns. Voltages between 500 and 1000 volts cause internal burns.

Another consequence of electric shock is ventricular fibrillation, which can even cause a short-term current of 110-230 volts to pass through the chest. This process can be fatal because in ventricular fibrillation, all myocardial cells move independently rather than in the coordinated manner necessary to pump blood and maintain circulation. At very high tensions, muscle contractions are so strong that the heart muscles can no longer move.

In addition, electricity leads to serious neurological disorders. It disrupts nervous control of the heart and lungs, which leads to disruption of the central nervous system, breathing and circulation. When current flows through the brain, the person almost always loses consciousness.

Very high voltage electricity and repeated shocks can cause neuropathy.

Electric shock is extremely dangerous to human health and life. Death can result from cardiac arrest due to ventricular fibrillation, although the most common cause of death in people with electrical shocks is extensive and deep burns. If the voltage is very high, charring of the body occurs.

Below is a table of current threshold values.

Voltage	Sensible (mA)	Non-releasing (mA)	Fibrillation (mA)
Variable (50Hz)	1,0-1.5	12,0-15,0	100,0
Permanent	6,0	60,0	300,0

Experience exchange

One of the main goals of electric grid companies is to ensure high-quality and reliable energy supply to consumers.
Carrying out work on power equipment without removing voltage significantly improves the quality of power supply and helps reduce the number of complaints about power quality from consumers. Therefore, we can assume that this method of performing work will be increasingly in demand every year, and the choice of a personnel training program for performing work will become increasingly relevant for network companies. Rosseti Moscow Region specialists are ready to share with colleagues the developed programs and their experience in using them. It is planned to invite representatives of other subsidiaries and affiliates of Rosseti PJSC to training to exchange experience and disseminate personnel training programs developed by power engineers in the capital region in all power grid companies in Russia.

Techniques for working under voltage

The method of working under voltage, due to the threat of electric shock to personnel, requires special vigilance and strict adherence to safety measures. Since when a worker closes parts of an electrical installation to the ground, electric current begins to flow, safe performance of work can be ensured provided that the person is isolated from the ground, or only from live parts, or from both at the same time.

Isolation of man from the earth

One option for working under voltage is to isolate the worker from grounded elements. Most often used on the contact network of urban transport and railway enterprises, power lines, lighting fixtures, etc. With this method of professional testing or repair of lines, the rule of uniform potential must be observed. This means that all crew members, tools and work areas must be brought to the same potential as the power line.

Figure 1: Isolated railcar tower

Consider Figure 1, here is an example of a device for isolating a worker on the contact network and the grounded part. This is a railcar tower that allows you to work without relieving stress.

The figure shows the tower itself A , the transition platform B and insulators I. To ensure safety, the tower is equalized to the potential of the wire by means of a shunt rod. This means that it is supplied with contact line voltage, which automatically passes under the worker’s feet and the person is at the same potential as the live parts and the working platform. While the I separate them from ground and prevent current from flowing, the insulators keep the circuit open and allow live work to be carried out safely.

Transition platform B in this situation acts as a neutral element, which allows you to move from the grounded deck of the railcar to the platform, which is energized. The direction of the person's movement is shown by the blue line. The transition technology prohibits the simultaneous movement of more than one person when working under voltage. One person moves first from the deck to platform B , and then from it to work platform A.

In the event of an emergency (breakdown of the insulator I , falling of a wire to the ground, overlapping of the insulation of the site), nothing will threaten the personnel. Since in the presence of a shunt element, current will not flow through the worker.

In this case, only a particular method of potential equalization is considered. But besides it, there are other devices:

In electrical networks, aerial platforms and insulated ladders are used for this purpose.
On the railway, in addition to the already discussed railcars - leiter.
For overhead lines 330 – 750 kV, helicopters can be used.

All of the above methods of working under voltage should only be performed by persons who have passed the knowledge test of industry regulations.

Isolation of a person from live parts, without isolating him from the ground

This live work requires the worker to be directly on the ground or on a permanently grounded structure. And all the manipulations that he performs on switchgears or on the line must be carried out using electrical protective equipment. They separate the worker from those elements that are energized and must be selected by the responsible manager in accordance with the voltage class for which the electrical installation is designed.

Work examples.

As an example, consider live work to replace a fuse, which can be done for devices up to 1 kV or above, depending on the situation.

Figure 2: Replacing a live fuse

As you can see in Figure 2, operation under voltage during fuse replacement in a device greater than 1 kV is shown. In this case, the employee must comply with the following safety requirements:

Use dielectric gloves;
Use a special shield to prevent sparks from getting into your face and eyes, in case such occur;
Hold the pliers up to the restrictive rings at arm's length;
Use only tools that are tested and suitable for the job.

Quite often, under voltage, fuses up to 1 kV are replaced in control circuits, and they are promptly removed during any scheduled or emergency work. In this case, the safety measures differ from work in circuits over 1 kV - the use of a face shield is not required, and the clamps are selected for a certain voltage class, and can be without restrictive rings, but in this case, separation of the person from the ground with an insulating stand, shoes or mat is required.

Another example would be working with an operating bar. At the same time, the employee can easily perform any manipulations with the same single-pole disconnectors and other operations.

Figure 3: Working with an insulating rod

Here, when maintaining electrical installations above 1 kV, much more stringent safety measures are applied. According to the technological maps, the employee is required to wear dielectric gloves and a shield. Check the operation of the rotating mechanism on the insulating rod. When performing manipulations without disconnecting the line, you must strictly observe the position of your hands relative to the restrictive ring.

Another option is to work with a voltage indicator in networks 6 - 110 kV. This device allows you to make sure that there is no voltage on the current-carrying elements when disconnecting the consumer. But first, the repair personnel are obliged to check its functionality, which is done by touching with a probe those tires or elements that are known to be energized.

Figure 4: Testing the voltage indicator

As you can see, Figure 4 shows the probe touching one of the AC buses in phase C, which is indicated by the letter A. If there is voltage in indicator B, the lamp will be visible. This work is also performed with dielectric gloves; the mark of the restrictive ring must be observed.

Isolation of the worker from live parts and ground

These works under voltage when operating electrical installations require special instructions. A person, in such a situation, must be simultaneously protected by insulating elements from both the ground and live parts. It should be noted that in various types of work, insulation from the ground can be performed for the purpose of protecting from step voltage, and sometimes it is performed as an additional or main barrier to the flow of current.

As an example of working under voltage in networks up to 1 kV, we can consider cleaning electric motor panels under load, testing insulators, and others.

Figure 5: Insulator performance test

As you can see, this work under voltage is performed from an insulating removable tower (leiter) L. During such manipulation, a person must be protected from live parts, due to the fact that the test simultaneously involves both the current-carrying and grounded part of the insulator. Personnel, at the same time, use dielectric gloves and a special measuring rod in order to protect themselves from voltage. But gloves and a bar are only additional protective equipment, while the leiter functions as the main means of isolating the worker from the ground.

Fundamentals of labor protection organization

The widespread use of electricity in all areas of production, as well as in everyday life, in addition to many advantages, also involves many risks, both for humans and for their work and living environment.

Labor protection is a system for preserving the life and health of people in the process of carrying out their work activities.

Improperly operating electrical equipment can cause electric shock, breakdown, fire and explosion.

Important! Electrical current used in homes, offices, workshops and shops can also cause serious injury or even death.

Preventive measures

For normal operation of home and industrial equipment, it is necessary to take some preventive measures. These are also included in the electrical safety rules:

it is necessary to adhere to all the information specified in the instructions supplied with the device;
the equipment is connected to a grounded network;
provide differential protection in bathrooms and children's rooms, separately install differential circuit breakers for boilers, dishwashers and washing machines;
periodically check the serviceability of all devices, sockets, inspect the insulation of wires and the integrity of the housing;
Do not use extension cords or carriers with damaged cords and plugs;
devices are not disconnected from the socket by wires;
portable lamps do not illuminate rooms with high humidity;
lamps of permissible power are screwed into the chandeliers, otherwise the plastic parts may melt;
do not leave lamp sockets hanging on the wires, as over time they begin to spark.

The whole world is in your hands - everything will be the way you want it

As I said.

There are only two ways to live life. The first is as if miracles do not exist. The second is as if there are only miracles all around.

A. Einstein

Design and types of manual furrowers

This equipment is a piece of metal pipe to which a metal arc is welded, which acts as a cutting element, and two pressing handles. More expensive models are equipped with a diamond tip.

There are two types of manual wall chasers:

For gating horizontal surfaces.
For working with vertical surfaces.

There are no fundamental differences between these devices. They differ from each other only in that the clamping handles are fixed at different angles, and the base tubes are bent differently. The difference in the device is due to the goal of correctly distributing the forces applied to the apparatus when gating both vertical walls and horizontal surfaces.

An example of the operation of a horizontal wall chaser in the video:

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