Protection classes for power tools against electric shock

Carrying out work using devices that use current is always associated with certain risks, both for the health of the person himself and for the surrounding area. For this reason, a special classification has been created that will help a campaign employee or a home handyman accurately determine the choice of tool for their tasks, as well as protect themselves and loved ones. Next, we will consider the basic principles of dividing devices into groups according to protection class.

Marking of power tools

At the moment, two types of markings are widely used for tools that work with electrical voltage.

The degree of danger of the device is depicted in the form of a simple schematic image:

1. A round icon, inside of which three horizontal lines are connected to one vertical in the form of an inverted letter T, means that this is a class 1 device;
2. A small square enclosed in a large one indicates the relation of the instrument to the second class;
3. The third is marked with a diamond with three vertical lines in the center.

Another marking method is also used, which indicates protection against penetration of the external environment into the device. The designation is implemented in a digital-alphabetic format, where the abbreviation IP appears first, and after the hyphen there are two numbers expressing the protection indicator.

The first value is responsible for the ingress of dense particles, where

1. – the device does not pass objects larger than 5 cm in diameter;
2. – protected from “falling through” of human fingers, that is, 12.5 mm (examples: electrical outlet, shield);
3. – objects larger than 2.5 mm, such as tools or cables, will not pass through;
4. – sealed against particles larger than 1 mm;
5. – full protection;
6. – recommended for rooms with a lot of dust, completely insulated.

The last number indicates the possibility of moisture getting into the device:

1. – the device will not allow vertically falling drops to pass through;
2. – protection against oblique falling drops (about 15 degrees);
3. – up to 45 degrees;
4. – protected from all sides;
5. – does not allow liquid to pass under pressure. It can be used outdoors during rain;
6. – invulnerable when submerged under water for a short period of time. This protection class is suitable for use on ships.

Thus, the presence of the IP-XX marking indicates the degree of protection of the device from the ingress of solid and liquid particles inside.

GOST power tool classes

The state standard for the safety of electrical appliances looks like this:

• Class 0 – characterized by the absence of grounding, implies the use of additional protective equipment;
• 01 – assumes the presence of a grounding device;
• 1 – safety level for household and computer equipment, has working insulation, a core in the wire, a ground-contact plug, and a grounding device. As long as wiring and surrounding maintenance standards are observed, it is safe to use;
• A class 2 device does not have grounding parts, the parts are well insulated;
• Class 3 devices operate at low voltage no higher than 42 V and do not require grounding.

Group 0I

This class of hand-held power tools is distinguished next in terms of electrical safety. The current-carrying parts of such equipment are insulated, but there is no insulation on the metal components of the structure. Protection here is realized by mechanical or electrical contact with the PE bus. This ensures potential equalization. It also prevents the formation of electrical charges on metal elements when the insulation is damaged.

Here the contact with the ground loop will be displayed with a special graphic symbol. According to existing standards, ground wires have a yellow-green tint.

Examples include both stationary and rail-mounted devices, but not beyond the length of the ground wires. That is, cranes, electric locomotives, transformer substations, etc. Such installations will always be operated only with grounding.

How to decipher the insulation class?

During the operation of electrical appliances, some parts invariably heat up, which leads to possible dangerous consequences, especially if a low-quality tool is chosen. The insulation class characterizes the resistance to thermal loads of the insulating material itself.

In this case, the designation takes the form of Latin letters and is deciphered as follows:

• Y – has the worst indicator. The winding is made of cotton, silk or cellulose fibers. Maximum heating is about 90 degrees;
• A – the same insulating materials, but they are already treated with a special compound, the temperature range is slightly wider, up to 105 degrees;
• E – winding made of resin or film, the limit is 120 degrees;
• B – mica is used, up to 130 degrees;
• F – synthetic materials and asbestos, resistant up to 155 degrees;
• H – usually fiberglass, withstands up to 180;
• C – the highest class, temperature limit at 180 degrees. Materials: ceramics, glass, quartz, inorganic materials.

What are protection classes and why are they assigned?

When using power tools, safety classification is of great importance. Knowing this provides additional protection against electric shock. It is most dangerous to use tools with a lower class. The degree of exposure to electric current decreases with increasing class index.

During operation of any power tool, the engine heats up. Over time, the material and the part itself become vulnerable. The insulation that ensures human safety also becomes unusable.

Insulation class is one of the most important parameters. It is this that gives an accurate description of the quality of the motor winding and heat resistance. The class decoding contains information about the temperature limit. Exceeding this parameter is dangerous, it leads to engine fire.

For your information! Protection classes of power tools are indicated by markings made of Latin letters. It indicates the optimal temperature regime.

What is subject to classification

Electrical safety classes of electrical equipment are established on all tools, both domestic and industrial. Each of the approved classes contains information about how resistant the tool is to heat, what level of insulation is provided if a person touches live parts during work.

The marking also contains information about the degree of protection of the housing from moisture and foreign objects.

Hand power tool classes

Such devices are distinguished by the presence of a power cable. Such a cable is protected from bending the cores and is insulated from contact with the device. In this category, there are three types of protection against electric shock by devices for manual use.

1. The cable of the first safety class has a zero core that connects the plug to the body of the object. Such equipment is not approved for home use and requires careful operation in compliance with safety precautions. Rubber gloves or shoes are required, a mat is optional;
2. The second class is already suitable for places with a high level of danger, but still requires the use of gloves;
3. Electrical equipment of the third class does not oblige the user to use special means and is suitable for home use; such devices include an ordinary household soldering iron.

Use of devices if its protection class is known

There is a clear set of recommendations and rules that must be followed to safely work with an electrical device. For example, if a tool belongs to “0” or “01” class, then it is not used without grounding. First class can only be used in production with gloves or a rubber mat.

No additional safety measures will have to be observed when working with class 2 equipment, except when work is performed inside tanks or wells.

The third class is suitable for any conditions.

Electrical safety classification

Previously, we have already reviewed the electrical safety classes of power tools, where we found out that not only the characteristics of the device itself play a role, but also the conditions under which it must be operated. No matter how reliably the device is protected, it also has a service life and recommended conditions. In order to increase the efficiency and safety of electrical appliances, standards have been established for determining the type of room.

Low-hazard rooms include places where the average temperature is constantly maintained no higher than 30 degrees; climate control systems can be used.

Humidity does not exceed 60%, and there are no dangerous chemical compounds or abundant dust in the atmosphere. This category includes residential and office premises that do not require renovation. This class also includes some workshops where sterility and order standards are observed around the clock, with climate control.

An increased level of danger in this case refers to everything that goes beyond the scope of the previous example. If at least one point is not met, the premises are assigned a second class. This is often caused by moisture or the proximity of conductive surfaces. This group includes workshops, warehouses, etc.

The third class includes especially dangerous buildings, where humidity reaches about 100%, and the concentration of toxic substances in the air is exceeded. Also, any room with a temperature above 35 degrees automatically falls into this category. This includes hazardous production workshops, as well as any covered areas.

What are the classes of protection against electric shock?

Categories of electrical equipment are divided according to characteristics and area of ​​use.

Electrical safety classification

To operate each electric powered tool, certain conditions must be met. They must be observed regardless of the reliability of the device. For this purpose, premises standards were introduced:

• The low hazard category includes places where the average temperature does not exceed 30 °C. The air should not contain particles of chemical elements. This group includes premises intended for housing and offices;
• The second class includes premises in which at least one condition is not met;
• the third category covers any covered warehouses, areas where the temperature can be above 35 ° C and there is an increased level of humidity.

The most electrically safe power tool belongs to class 0. The table clearly defines the electrical safety class of a power tool:

Power classification

One of the characteristics that shows how long a tool can work is power. Groups for this parameter include:

• Industrial are professional portable power tools that can operate for up to 15 hours. They have reduced safety data;
• Heavy Duty - have the same characteristics as the first category, but provide additional protection from dust and moisture;
• The Professional class is intended for non-professional tool users. It has high safety requirements.

Tools belonging to the Hobby category are suitable for home use. They can be in working condition for no more than 30 minutes. Their biggest advantage is the high level of security.

Classification by purpose

The most common division of a tool is by its purpose:

• if holes are needed, drills, hammer drills, and chippers will be required;
• planes, grinders and polishers are used to polish surfaces;
• Grinders and miter saws are used for cutting material.

Auxiliary tools are included in a separate category.

Classification by method of operation

There is also an electrical safety class for the tool based on the method of operation. There are two types:

• battery type, which are also called manual. Their advantages are safety of use and easy transportability. But there is also a minus - short working time without recharging;
• stationary - instruments connected to the network. In terms of operation, they are no different from manual ones. They have more power and efficiency.

Important! Stationary tools in the form of machines are prohibited for use without certain qualifications.

Classification according to the degree of protection against penetration of foreign objects

The classification of power tools according to the degree of protection is divided not only according to the ingress of foreign objects, but also according to the touches of craftsmen and objects inside the tool. The classification is intended not only to protect the person, but also the instrument itself from damage.

If the marking contains a zero value, then no protection is installed at all. Electrical safety class 1 indicates protection from objects not exceeding 50 mm.

Item protection groups

Classification by safety level

Electrical safety classes of power tools are divided into the following:

• “0”—the rated voltage is typical only with working insulation;
• “01” - has grounding and insulation;
• “02” - main characteristic - double insulation of parts with which contact is established;
• “03” are low-power tools, their power does not exceed 45 V.

The last group does not require grounding.

Classification by heat resistance

The division into heat resistance classes depends on the material used in the winding:

• the lowest indicators are marked Y. The materials used are cotton, cellulose, and silk;
• group A implies the same material as in the first category, but it is treated with a dielectric. Its temperature limit reaches 105 °C;
• in category E, resin is used for winding;
• the highest class C involves heating up to 180 °C. In such groups, the winding is made of mica, glass and ceramics.

For your information! These groups apply to both household and professional tools.

Insulation resistance to overheating

Insulation class is one of the important parameters of electrical equipment. It characterizes the maximum possible temperature level for the electric motor. Silk and cellulose are the least resistant to heat. Mica, ceramics, and glass maintain the temperature as much as possible.

In which premises it is not allowed to use class 0 power tools?

Class 0 includes any devices operating at voltages above 42 V without grounding. Until recently, all household appliances belonged to this class, because... They are originally intended for use in low-hazard areas. Moreover, it is prohibited to use devices of this class in buildings of the second and third classes without a special housing and protective equipment. Any actions with them are carried out by specially trained people in strict accordance with safety precautions.

To summarize, it should be emphasized that before starting any electrical appliance, you should check for integrity, sensibly assess the situation and the environment, always check the condition of the sockets and monitor the voltage in the network. This will prevent many disastrous consequences that could have been avoided by being vigilant.

Group III

This will designate electrical equipment that is powered only through a voltage-sensing transformer. Therefore, devices of this class will operate on voltages of 36 and 48 V (AC or DC voltage, respectively).

Protection is ensured by the fact that the power is supplied from an ultra-low voltage that is safe for humans. And in the device itself there is no voltage greater than it.

This class includes many portable devices powered by rechargeable batteries, as well as devices with a low-voltage external power supply. These include laptops, flashlights, players, radios, etc. A grounding contact is not provided here in principle.

If the shell is conductive, then its connection to grounding conductors is allowed (but only if this is provided for in the standards for this device). Grounding may also be present for functional purposes (depending on the purpose of this grounding).