Safety measures when using household electrical appliances and tools. Scheme, description

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Safety measures when using household electrical appliances and tools. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Electrical safety, fire safety

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In terms of electrical safety, a special place is occupied by portable household machines, heaters, power tools and portable lamps, in which all three methods of electrical protection are widely used.

According to the method of protecting a person from electric shock, electrical products are divided into 5 classes: 0, 0I, I, II, III.

К class 0 include products that have working insulation without grounding elements or other protection against electric shock.

К class 0I - products with working insulation, an element for grounding and a wire without a grounding conductor for connection to a power source.

К class I - products with working insulation and an earthing element If a class 1 product has a wire for connecting to a power source, it must have a grounding conductor and a plug with a grounding contact for plugging into a socket with an additional socket.

К class II - products with double insulation or reinforced insulation without earthing elements.

К class III - products that do not have either internal or external electrical circuits with a voltage higher than 42 V.

Most household electrical appliances are class 0 and 01, which is why they are not provided for grounding. From an electrical safety point of view, they should be of limited use. Of all the protection classes that ensure the safety of using electrical appliances, preference should be given to class II. The metal cases of electrical receivers in rooms with increased danger, especially dangerous and in outdoor installations must be zeroed, with the exception of electrical receivers with double insulation.

Portable power receivers are grounded with a special core (the third one for single-phase current power receivers), located in the same sheath with the phase cores of the portable wire and attached to the power receiver case and a special contact of the plug-in plug. The cross section of this core must be equal to the cross section of the phase wires. The cores of wires and cables used for grounding portable power receivers must be copper, flexible, with a cross section of at least 0,75 mm2.

Grounding of metal parts with double insulation of the electrical receiver is prohibited in order to avoid shunting double insulation.

Distinctive sign of protection class II - "square in a square" on the nameplate or machine body.

Electrified tool protection classes:

I - machines with insulation of all live parts and plugs with earthing contact;

II - machines in which all live parts have double or reinforced insulation;

III - machines for a rated voltage not exceeding 42 V, in which neither internal nor external circuits are under a different voltage.

The possibility of using power tools is limited depending on the category of premises according to the degree of electrical safety. So, in rooms without increased danger:

Class I - use is permissible only with the use of personal protective equipment;

II and III classes - application is possible without the use of personal protective equipment.

In hazardous areas and outdoors:

I class - application is unacceptable;

II and III classes - application is possible without the use of personal protective equipment.

The exception is the use of class II power tools in the production of construction and installation works with the use of personal protective equipment.

In especially dangerous conditions (wells, etc.), the use of power tools of classes I and II is unacceptable, class III is possible without the use of personal protective equipment. An exception is the use of class III power tools in the production of construction and installation works with the use of personal protective equipment.

The portable lamp must be electrically safe. Its cartridge is fixed in a special handle made of durable electrically insulating moisture-resistant material. The lamp must be covered with a glass cap and safety net. For a portable lamp, double-insulated hose wires are used (the wires are isolated from each other, they have a common additional insulation from the environment).

When performing work in rooms without increased danger, portable lamps with a voltage of 220 V are used. In rooms with increased danger and in especially dangerous rooms, manual electric lamps with a voltage of less than 42 V are used.

It is possible to work in especially unfavorable conditions using lamps with a voltage of no higher than 12 V.

Author: Bannikov E.A.

See other articles Section Electrical safety, fire safety.

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