Exemption from the action of electric current. Occupational Safety and Health

OCCUPATIONAL SAFETY AND HEALTH
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Exemption from the action of electric current. Occupational Safety and Health

Occupational Safety and Health

Occupational Safety and Health / Providing first aid to the injured

In case of electric shock it is necessary to free the victim from the action of the current as soon as possible, since the severity of the electrical injury depends on the duration of its action on the body.

Touching live parts under voltage causes in most cases involuntary convulsive muscle contraction and general excitation, which can lead to disruption and even complete cessation of the activity of the respiratory and circulatory organs. If the victim holds the wire with his hands, his fingers are compressed so tightly that it becomes impossible to release the wire from his hands. Therefore, the first action of the person providing assistance should be to quickly turn off the part of the electrical installation that the victim touches.

You can turn off the electrical installation using a switch, knife switch or other disconnecting device (Fig. 1), as well as by removing the fuses, the plug connector, creating an artificial short circuit on the overhead line (VL) by "blow", etc.

Exemption from the action of electric current
Fig.1 Releasing the victim from the action of the current by turning off the electrical installation

Exemption from the action of electric current
Fig. 2 Release of the victim from the action of current in electrical installations up to 1000 V by discarding the wire with a board

If the victim is at a height, then turning off the installation and thereby freeing the victim from the action of the current can cause him to fall from a height. In this case, measures must be taken to prevent further injury.

When the unit is turned off, the electric light may go out at the same time, therefore, in the absence of daylight, it is necessary to provide lighting from another source (turn on emergency lighting, battery lights, etc., taking into account the explosion and fire hazard of the room), without delaying the shutdown of the unit and providing assistance to the victim.

If it is not possible to quickly turn off the electrical installation, then measures must be taken to separate the victim from the current-carrying parts that he touches. At the same time, in all cases, the assisting person should not touch the victim without taking appropriate precautions, as this is life threatening. He must also ensure that he himself does not come into contact with the current-carrying part or under the voltage of the step, being in the zone of the spreading of the earth fault current.

At voltages up to 1000 V, to separate the victim from live parts or wires, use a rope, stick, board or some other dry object that does not conduct electric current (Fig. 2). You can pull the victim away from current-carrying parts by the clothes (if it is dry and lags behind the body), for example, by the hems of a jacket or coat, by the collar, while avoiding touching the surrounding metal objects and body parts of the victim not covered by clothing (Fig. 3). You can pull the victim by the legs, while the assisting person should not touch his shoes or clothes without good insulation of his hands, since shoes and clothes can be damp and conduct electric current. To isolate the hands, the assisting person, especially if he needs to touch the body of the victim, not covered by clothing, must put on dielectric gloves or wrap his hand with a scarf, put on a cloth cap, pull the sleeve of a jacket or coat over his hand, throw a rubber carpet, rubberized material over the victim ( raincoat) or just dry matter. You can also isolate yourself by standing on a rubber carpet, a dry board or some kind of non-conductive bedding, a bundle of dry clothes, etc. When separating the victim from live parts, you should use one hand (Fig. 4).

Exemption from the action of electric current
Rice. 3. Release of the victim from the action of current in installations up to 1000 V by pulling dry clothes

Exemption from the action of electric current
Rice. 4. Separation of the victim from the current-carrying part, energized up to 1000 V

If an electric current passes into the ground through the victim and he convulsively squeezes a current-carrying element (for example, a wire) in his hand, it is easier to interrupt the action of the current by separating the victim from the ground (by slipping a dry board under him or pulling his legs off the ground with a rope or clothing), observing at the same time the above precautions both in relation to oneself and in relation to the victim. You can also cut the wire with an ax with a dry wooden handle (Fig. 5) or make a break using a tool with insulating handles (cutters, pliers, etc.).

Exemption from the action of electric current
Rice. 5. Release of the victim from the action of current in installations up to 1000 V by cutting wires

You can use a tool without an insulating handle by wrapping its handle with a dry cloth. It is necessary to cut the wires phase by phase, i.e., cut the wire of each phase separately, while insulating yourself from the ground (standing on dry boards, a wooden ladder, etc.).

At voltages above 1000 V, to separate the victim from live parts, it is necessary to use protective equipment: put on dielectric gloves and boots and use a rod or insulating tongs designed for the appropriate voltage (Fig. 6).

Exemption from the action of electric current
Rice. 6. Release of the victim from the action of current in installations above 1000 V by discarding the wire with an insulating rod

On overhead power lines (VL) 6-20 kV, when it is impossible to quickly turn them off from the supply side, an artificial short circuit should be created to turn off the VL. To do this, a flexible bare conductor must be thrown onto the wires of the overhead line. The stranded conductor must have a sufficient cross section to avoid burnout when a short circuit current passes through it. Before throwing a conductor, one of its ends must be grounded (attached to the body of a metal support, grounding descent or a separate ground electrode, etc.), and it is desirable to attach a load to the other end for ease of throwing. It is necessary to throw the conductor so that it does not touch people, including those providing assistance and the victim. When throwing the conductor, it is necessary to use dielectric gloves and boots.

The person providing assistance should be aware of the danger of step voltage if the current-carrying part (wire, etc.) lies on the ground. It is necessary to move in this area with extreme caution, using protective equipment for isolation from the ground (dielectric galoshes, boots, carpets, insulating stands) or objects that conduct electricity poorly (dry boards, logs, etc.). Without means of protection, one should move in the zone of spreading of the earth fault current by moving the feet on the ground and not tearing them one from the other (Fig. 7).

Exemption from the action of electric current
Rice. 7. Correct movement in the zone of spreading of the earth fault current: a - distance from the point of earth fault of the current-carrying part; b - footprints

After separating the victim from the current-carrying parts, he should be taken out of this zone at a distance of at least 8 m from the current-carrying part (wire).

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