The existing classes of power tools help to figure out how well this or that product protects the person working with it from electric shock. In addition, the level of isolation from accidental contact with parts that may be energized is subject to classification. The label also includes an indicator of the protection of the instrument from the ingress of solid particles and water penetration. The class of insulation indicated therein characterizes the thermal resistance of the motor winding.
Power tools: chainsaw, hammer drill, electric drill, circular saw.
Varieties and methods of protection
From the point of view of operational safety, all electrical appliances and tools are divided into the following classes:
- 0 (rated voltage is more than 42 V, without grounding, there is only working insulation);
- 01 (have working isolation and the device for grounding, but there is no grounding conductor in a wire to the power supply);
- I (there is a working insulation, equipped with an element for grounding, a wire with a grounding core and a plug with a “ground” contact);
- II (there are no grounding elements, but there is reinforced or double insulation of parts of the electric tool that are accessible to touch);
- III (receive power from a source with a voltage up to 42 V, are not subject to grounding).
The international marking IP-xx denotes the class of protection against the entry of foreign substances from the outside. It can be used not only for the power tool itself, but also for auxiliary products: plugs, shields, sockets, switches. The numeric encoding in it goes directly after the abbreviation IP. The first digit indicates how well the product is protected:
- 0 - no protection of the instrument against mechanical impact;
- 1 - prevents from contact with the hand or particles of more than 50 mm in diameter;
- 2 - from contact with fingers or particles exceeding 12.5 mm;
- 3 - from the ingress of foreign bodies with a diameter of not less than 2.5 mm;
- 4 - isolates from particles larger than 1 mm;
- 5 - complete protection from contact with foreign bodies;
- 6 - fully protects against contact and penetration of dust.
The second number in the marking indicates the insulation level of the power tool from moisture penetration. The higher this indicator, the more reliable it is:
- 1 - protects only from vertically falling drops of water;
- 2 - closes from moisture at an angle of 150;
- 3 - protection against drops with a dip angle of up to 450;
- 4 - full protection when water is pouring from all sides;
- 5 - safety of the product when water flows from all sides and under pressure;
- 6 - protection for short flooding.
The need for additional insulation and grounding
Cross-sectoral rules on labor protection.
Currently, power tools of classes “0” and “01” are allowed to be operated only if it is built into another device having a grounded housing. Equipment of class “1” is marked with a ground symbol (there are three horizontal lines in the circle and one vertical above them). Intends for operation only in production conditions, except for especially dangerous rooms. For safety reasons, it is necessary to use at least one of the isolating agents: rubber gloves, a rug or shoes. You can do without them only in cases when the instrument is connected through auxiliary equipment (isolation transformer, frequency conversion device, RCD).
Equipment of class “2” does not require grounding, since, in addition to the main insulation of the power tool, it has additional, autonomous isolation of its individual components and parts. It is called double, and reinforced implies an isolation level not lower than that of double. Products are marked in the form of 2 squares, one inside the other. You can use them without additional protection. The exceptions are objects with particular danger: wells and metal tanks. In them, the safety of work requires the presence of at least one of the dielectric protective equipment. Products of class "3" are labeled in the form of 3 vertical stripes inside a diamond. They can be used everywhere and without restrictions.Back to table of contents
Mechanical protection device
Modern electrical equipment should protect a person not only from electric shock, but also from injuries caused by contact with individual nodes.
Connection and rules of work with power tools.
At the same time, the device itself may suffer if solid particles or water enter it. If figure 1 is in the first place in the IP classification, this equipment can be used only in those places where it functions without human participation.
Eliminate the ingress of fingers inside the case is already the 2nd class of protection devices. This includes receptacles and distribution boxes. The safety of the product from getting into the tools or thick cable can provide a 3rd class. The smallest particles will be screened out if the 4th class of protection was involved in the instrument. A higher level is required when isolated from dust. These are classes 5 and 6 for ordinary and extremely dusty rooms, respectively.
Most of the operating instructions for household appliances contain the requirement to completely eliminate the ingress of moisture inside. Nevertheless, the IP system provides an indicator of the level of protection of the power tool from water ingress. For example, the 5th class ensures the stable operation of equipment in open space in rainy weather, and the 6th ensures the safety of the device on the ship in a storm. Thus, IP-45 marking means that this product can be used outside in the rain, even the smallest branches and stones will not fall into it.Back to table of contents
Overheating Insulation Resistance
Classes of electrified tools are protected by type of electric shock.
One of the parameters of electrical equipment is the class of insulation. It shows the maximum level of increase in the temperature of the electric motor, at which one or another type of insulating material can still remain safe. This indicator is denoted by the Latin letter, which corresponds to the maximum allowable temperature of the moving parts of the mechanism at an ambient temperature of 400WITH.
The least resistant to heat are cellulose fibers, natural silk, cotton. They correspond to the class Y and the maximum allowable temperature 900C. The same materials, but impregnated with dielectric, correspond to class A and temperature 1050C. To ensure the safety of the winding at a temperature of 1200C (class E), artificially produced organic films and resins are used, as well as their combination with other materials.
The following classes of resistance to heat - B, F and H, which correspond to the temperature values 1300, 1550 and 1800C, can be achieved with the help of materials such as mica, asbestos, fiberglass. In the first case, organic compounds are used as an impregnation or binding element. In the second, synthetic binders are used that can correspond to a given level of resistance to heat. In the third case, these are silicone impregnations, binders and elastomers in combination with the base material. To obtain insulation class C, in which the coating withstands temperatures above 1800C, use mica, glass, quartz, ceramics, or a combination thereof. Inorganic, organometallic compounds can be used as binders or their use can be completely excluded.
Not to mention another classification, designed mainly for buyers. As you know, power tools can be household and professional. If you choose among the products of well-known companies that value their business reputation, the difference, first of all, is observed in price, but not in quality. Just a professional tool designed for long-term work, and household products should cool for 10-15 minutes after every 15-20 minutes of work.