What class of power tools can be used without using

What class of power tools can be used without using

VI. Occupational safety requirements when working with electrified

The following requirements shall be observed when working with portable hand-held electric lights:

1) when the danger of electric shock is exacerbated by cramped space, awkward position of the worker, contact with large grounded metal surfaces (e.g. working in drums, metal tanks, gas ducts and furnaces of boilers or in tunnels), the power supply for portable lights must not exceed 12 V;

2) when handing out portable lights, workers issuing and receiving them, should make sure that the serviceability of lamps, cartridges, plugs, wires;

Hand Tools VS Power Tools. Are Hand Tools still Relevant in 2020?

3) repair of faulty portable lamps shall be performed by the employees having relevant qualification.

Repair of portable light fixtures may not be performed without disconnecting them from the power supply.

When carrying out work involving the use of portable electric lights inside closed and confined spaces (metal tanks, wells, compartments, gas ducts, furnaces of boilers, drums, in tunnels) step-down transformers for portable electric lights must be installed outside closed and confined spaces, and their secondary windings must be grounded.

If the step-down transformer is also an isolating transformer, its secondary circuit must not be connected to earth.

The use of autotransformers to lower the supply voltage of portable electric lamps is prohibited.

Before handing over electrified tools to the employee (hereinafter. power tools) an employee designated by the employer to be responsible for power tools in good working order shall check:

1) serviceability, serviceability of the cable, protective covers (if any) of the plug and the switch, reliability of fastening of parts of the power tool;

2) serviceability of the electric tool grounding circuit and absence of winding short circuit to the frame;

3) idle operation of the power tool.

No power tool may be used if it is out of order or if its periodic inspection has expired.

Before starting work with the power tool, checks shall be made:

1) the class of the power tool, its ability to be used in terms of safety in accordance with the place and nature of work;

2) correspondence of voltage and current frequency in the electric network to the voltage and current frequency of the electric motor of the power tool;

3) operability of the residual current device (depending on the working conditions);

4) reliability of attachment of removable tool.

Classes of electric tools, depending on how the implementation of protection against electric shock are as follows:

0 class. power tools in which protection against electric shock is provided by basic insulation and there is no electrical connection of exposed conductive parts (if any) to the protective conductor of the fixed wiring;

I class. power tools in which protection against electric shock is provided by basic insulation and the connection of exposed conductive parts accessible to contact with the protective conductor of the fixed wiring;

II class. power tools in which protection against electric shock is provided by the use of double or reinforced insulation;

class III. power tools in which protection against electric shock is based on source of safety extra-low voltage not exceeding 50 V and in which no voltage above the safety extra-low voltage occurs.

Touchable metal parts of class I power tools, which could become live if the insulation is damaged, are connected to an earthing clamp. Class II and III power tools are not grounded.

the grounding of the power tool enclosure is performed by a special wire of the supply cable, which must not at the same time serve as a conductor of the operating current. Do not use the neutral conductor for this purpose.

The housings of converters, step-down transformers and safety isolation transformers (hereinafter. isolation transformers), depending on the mode of operation of the neutral point of the network supplying the primary winding, shall be earthed or grounded.

Earthing of the secondary winding of isolating transformers or transformers with separate windings is not permitted.

Connection (disconnection) of auxiliary equipment (transformers, frequency converters, protective shutoff devices) to the network, its checking, as well as troubleshooting shall be performed by electricians.

Inserting the working part of the power tool into the chuck and removing it from the chuck, as well as adjusting the power tool should be done after disconnecting the power tool from the mains and stopping it completely.

When working with power tools it is forbidden:

1) Connect power tools with voltage up to 50 V to the public mains through an autotransformer, resistor or potentiometer;

2) bring inside containers (drums and furnaces of boilers, transformer tanks, turbine condensers) a transformer or a frequency converter, to which the power tool is connected.

When working in underground structures, as well as during excavation work, the transformer must be outside these structures;

3) pull the cable of the power tool, put a load on it, allow it to cross with cables, electric welding cables and gas-welding hoses;

4) operate the power tool from random stands (window sills, drawers, chairs), on a ladder;

5) remove chips or filings by hand (chips or filings should be removed with special hooks or brushes after the power tool has come to a complete stop);

6) handle icy and wet parts with the power tool;

7) leave the power tool connected to the mains without supervision, as well as hand it over to unauthorized persons;

8) independently disassemble and repair (troubleshoot) the power tool, cables and plugs to unqualified workers.

When working with an electric drill, objects to be drilled must be secured.

When working with an electric drill, objects to be drilled must be clamped in place and must not come into contact with the rotating power tool body;

use a lever to push down on the working power drill.

Grinders, saws and planers shall have a protective guard of a working part.

It is prohibited to work with power tools which are not protected against dripping and splashing and have no distinctive marks (a drop or two in a triangle), in conditions of exposure to dripping and splashing, as well as in open areas during snowfall or rain.

Such power tools may be operated outdoors only in dry weather, but if it rains or snows. Outdoors on dry ground or decking.

Work with class 0 power tools in particularly hazardous locations and under particularly adverse conditions (in vessels, apparatus and other metal containers with restricted freedom of movement and egress);

Work with class I power tools under particularly adverse conditions (in vessels, apparatus, and other metal containers with limited portability and egress).

Class III power tools may be operated without the use of electrical protection equipment in all areas.

It is allowed to work with power tools of class II without using electrical protection means in all premises, except for work in especially unfavorable conditions (work in vessels, apparatus and other metal containers with limited possibility of movement and egress), in which case work is prohibited.

When suddenly stopping the power tool, when carrying the power tool from one workplace to another, and when interrupting work with the power tool and at the end of work, the power tool must be disconnected from the mains using the plug.

If during work, if any malfunction of the power tool is noticed or if the person working with the power tool senses an electric current, parts of the power tool overheat or a smell of smoldering electric wiring insulation, the work shall be stopped immediately and the power tool shall be returned for inspection and repair.

Power tools and appliances (including auxiliary equipment: transformers, frequency converters, safety devices, extension cables) must be checked at least once every 6 months by an employee who has electrical safety group III or higher and is appointed by the employer to be responsible for the condition of the power tools and appliances.

The periodic inspection of power tools and accessories includes:

testing of idle operation for at least 5 minutes;

measurement of insulation resistance with a megohmmeter at a voltage of 500 V for 1 minute with the switch in the “on” position, the insulation resistance must be at least 0.5 Mohm (except for cordless tools);

Checking that the grounding circuit is in good working order (for Class I power tools).

The results of the power tool check shall be recorded in the logbook.

The cases of power tools, step-down and isolating transformers, and frequency converters shall be marked with inventory numbers and the date of the following tests.

It is forbidden to work with power tools that have expired their regular testing, maintenance, or if at least one of the following malfunctions occurs:

1) Damage to the plug, cable or its protective tube;

3) arcing of brushes on the collector, accompanied by appearance of circular fire on its surface;

4) leakage of lubricant from the reducer or ventilation ducts;

5) smoke or smell typical of burning insulation;

6) appearance of increased noise, knocking and vibrations;

7) breakage or appearance of cracks in the housing part, handle, safety guard;

8) damage to the working part of the power tool;

9) loss of electrical connection between the metal part of the housing and the zero clamping pin of the power plug;

The power tool shall be stored in a dry room, equipped with special racks, shelves and drawers, which ensure storage of the power tool with consideration of the requirements for storage conditions of the power tool, specified in the technical documentation of the organization-manufacturer.

It is prohibited to store the power tools in two or more unpacked rows.

When transporting power tools, precautions must be taken to prevent damage to the tool. In this case, the requirements of technical documentation of the manufacturer shall be observed.

Electrical Safety Group when working with hand-held power tools

Personnel with electrical safety group II or higher shall be allowed to work with electric tools of class I in rooms with increased danger of electric shock and outdoors, and personnel with electrical safety group I shall be allowed to work with electric tools of class II and III. Persons certified to work with power tools must first have undergone training and a safety check and must have a record in their qualification certificate on their permit to work with power tools. Electrical engineers having electrical safety group II or higher shall be allowed to work with power tools without any record in their qualification certificate for special operations.

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3.2.2. Power tools shall be of the following classes: Class I power tools in which all live parts have insulation and the plug has an earthing contact. Class I power tools may have all live parts with basic insulation and separate parts with double or reinforced insulation; Class II power tools have all live parts with double or reinforced insulation. This power tool does not have a grounding device. The rated voltage of power tools of classes I and II shall be not more than: 220 V for DC power tools, 380 V for AC power tools; III power tools with a rated voltage not exceeding 42 V, in which neither internal nor external circuits are otherwise energized. Class III power tools are designed to be powered from a safe extra-low voltage. Note. If the safety extra-low voltage is obtained by converting a higher voltage, this must be done by means of a safety isolation transformer (hereinafter referred to as “isolating transformer”) or a converter with separate windings.

3.2.3. A non-detachable, flexible power cord with a plug must be furnished with the power tool. The non-detachable, class I flexible cable of the power tool should have a core wire which connects the grounding clamp of the power tool to the ground contact of the power plug. The cable should be protected against abrasion and kinks where it enters the power tool with an insulating sleeve. The tube must be fixed into the housing of the power tool and protrude from the tool over a length of at least five cable diameters. Do not attach tubing to the cable outside the tool.

3.2.4. In order to connect a single-phase power tool, the hose cable must have three conductors: two for voltage supply, one for grounding. To connect a three-phase tool, a four-core cable is used, one core of which serves as grounding. These requirements apply only to power tools with earthed housings.

3.2.5. The metal parts of the class I power tool which are accessible to touch and which may become energized in case of a fault in the insulation must be connected to the earthing terminal. Class II and III power tools are not earthed. The power tool housing must be grounded by a special wire of the power supply cable, which must not at the same time serve as a conductor of the operating current. Do not use the neutral work lead for this purpose. 6. The power plug must have the appropriate number of blades and one earth contact. The plug should be designed so that the earthing contact is made before the switch-on time and broken after the switch-off time.

3.2.6. Class III plugs of power tools must be designed so that they are not connected to sockets with a voltage greater than 42 V.

3.2.7. Portable step-down transformers, isolating transformers and converters must have a cable (cord) with a plug for connection to the mains on the higher voltage side. Cable length must not exceed 2 m. Its ends must be attached to the transformer terminals by soldering (welding) or bolted connection. On the low-voltage side of the transformer, sockets for plugs shall be provided.

3.2.8. The housings of converters, isolating and step-down transformers, depending on the neutral condition of the network supplying the primary winding, must be earthed or grounded according to the requirements of par.1.7.39 и 1.7.44 of “The Rules for Electrical Installations” (M.: Energoatomizdat, 1985). Secondary winding of step-down transformers must be grounded. Earthing of the secondary winding of transformers or converters with separate windings is not allowed.

3.2.9. Whenever power tools are given out, the following shall be checked: completeness and reliability of parts fastening; serviceability of cable and plug, integrity of insulating parts of body, handle and covers of brush holders, availability of protective covers and their serviceability (visual inspection); clearness of switch operation; idle runnability. 110 Class I power tools must, in addition, have a properly functioning earthing circuit checked between its chassis and the earthing contact of the plug and must be provided with personal protective equipment (electric gloves, galoshes, mats) or an isolating transformer or converter with separate windings or a safety disconnecting device. Power tools which do not meet at least one of the above requirements or whose periodic inspection has expired may not be used. Before starting work it is necessary to check: compliance of voltage and frequency of current in the electric network with voltage and frequency of electric motor of the power tool, indicated on the plate; reliability of fastening of working executive tools: drills, abrasive discs, circular saws, wrenches, etc.

3.2.10. When working with power tools of class I, the use of personal protective equipment (dielectric gloves, galoshes, mats, etc) is required.п.) is mandatory, unless: only one power tool is supplied with power from an isolating transformer; the power tool is supplied with power from a separate motor-generator set or a frequency converter with isolating windings; the power tool is supplied through a safety disconnecting device. The use of dielectric gloves or electrically conductive floor mats or carpets in rooms with no increased risk of electric shock to the personnel is required.

3.2.11. Class II and III power tools may be operated without the use of personal protective equipment in rooms with no increased risk of electric shock to workers.

3.2.12. In vessels, apparatus and other metal structures with limited possibility of movement and egress from them, it is permitted to work with power tools of classes I and II provided that only one power tool is powered from an autonomous motor-generator set, isolating transformer or frequency converter with isolating windings, as well as with power tools of class III. The power supply (transformer, inverter, etc.п.) must be outside the vessel and its secondary circuit must not be grounded.

3.2.13. Do not connect power tools with a voltage of up to 42 V to the public mains using an autotransformer, resistor or potentiometer.

3.2.14. It is prohibited to bring inside furnaces and drums of boilers, condensers of turbines, transformer tanks and other vessels a transformer or a frequency converter to which electric tools are connected. When working in underground structures (wells, chambers, etc.).п.3 15 14), as well as during excavation work, the transformer must be located outside of these structures.

3.2.15. Connecting (disconnecting) auxiliary equipment (transformers, frequency converters, protective disconnecting devices, etc.п.) to the mains, its checking, as well as troubleshooting shall be made by specially trained personnel having electrical safety group III or higher.

3.2.16. The cable of the power tool must be protected against accidental contact with hot, damp or oily surfaces. Do not pull, twist or bend the cable, do not place any loads on it, and do not allow it to cross with ropes, cables or gas-welding hoses.

3.2.17. The working part of the power tool must be set into a chuck and removed from the chuck as well as the tool must be adjusted after disconnecting it from the mains with the plug and stopping completely.

3.2.18. No one may work on the power tool and have it disassembled or repaired by themselves, except the personnel mentioned in the notice in the ” 3. 3.2.15.

3.2.19. Working with power tools from a ladder is prohibited.

3.2.20. Do not remove chips or filings with your hands while the tool is in operation. Chips must be removed after the power tool has come to a complete stop using special hooks or brushes.

3.2.21. Securely fasten items to be drilled with the electric drill when working with the drill. No one may touch rotating cutting tools with their hands.

Persons allowed to work with power tools must first be trained and tested on their knowledge of health and safety instructions and have a record in their qualification certificate of admission to work with

Electrical workers with a 2nd electrical safety group or higher are allowed to work without a record in their qualification certificate for the right to perform special works.

Persons with electrical safety group 1 may be allowed to work with electrical portable, mobile devices, devices in the following cases:

When using class P power tools, in which all live parts have double or reinforced insulation, without grounding devices;

if class III power tools, designed for safety extra-low voltage (below 42 V), are used, in which neither internal, nor external circuits are under other voltages.

Class I power tools (all live parts have basic insulation, and individual parts have double or reinforced insulation, and the plug has a grounding contact) may only be operated in rooms with increased danger of electric shock and outside rooms by personnel with an electrical safety group of at least P.

When issuing and receiving portable or mobile electrical equipment, tools must be checked:

the completeness and reliability of the parts fastening;

serviceability and integrity of the insulation of the power cable (cord),

plug, housing insulation, handle, and

the availability and serviceability of safety covers;

Before switching on the power tool, you should also check: 220 V. for DC power tools;. Trial operation of the switch;

Before switching on the power tool, you should also check:

Compliance of the voltage and frequency of the electric network with the voltage and frequency of the electric motor of the tool;

Reliability of fixing of working executive tools, drills, abrasive discs, circular saws, wrenches, etc., to the tool.

Rated voltage of power tools of classes 1 and P must not exceed:

220 V. for DC tools;

380 V. for AC power tools.

Rated voltage of class SH power tools is 42 V as long as neither internal nor external circuits are otherwise energized.

Do not pull, twist or bend cables and wires, do not hold on to the wire with your hands, and do not allow them to cross with ropes, cables and gas-welding hoses,

use personal protective equipment (electric gloves, galoshes, mats, etc.) when operating an electric tool of class 1.п.) is mandatory, except in the following cases:

only one power tool is powered by an isolating transformer;

the power tool is powered by an independent motor/generator set or a frequency converter with isolating windings;

the power tool is powered via a safety disconnecting device.

In rooms without increased danger of electric shock to personnel, dielectric gloves must be worn, and in rooms with conductive floors, dielectric galoshes or mats must also be worn.

It is allowed to work with electric tools of classes P and S without wearing personal protective equipment against electric shock in rooms without increased danger, i.e.е. in dry rooms with normal temperature and humidity (up to 60%), insulated floors and few earthed objects.

It is forbidden to work with power tools:

in conditions of exposure to dripping and splashing, in open areas during snowfall or rain;

if the periodic inspection has expired;

in case of malfunction, damage.

class, power, tools, used, using

plugs of power tools and appliances shall be plugged into appropriate electrical sockets only of such voltage and type of current (DC or AC) as are indicated on the covers of the sockets and plugs.

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When moving power tools and electric lights from one workplace to another, as well as when interrupting work and at the end of work, they must be disconnected from the mains by the plug.

It is forbidden to bring inside drums, gas ducts and furnaces of boilers, tunnels, etc.п. portable step-down transformer.

autotransformers, choke coils, rheostats, resistors, potentiometers must not be used to step down the voltage of portable tools and lamps.

setting the working part of the power tool in a chuck and removing it from the chuck, as well as making adjustments, shall be done after the moving parts are completely stopped and the tool is disconnected from the mains by the plug.

When working with an electric drill, objects to be drilled must be securely fastened. Do not touch the rotating cutting tool with your hands.

When drilling with an electric drill using a pressure lever, make sure the end of the lever is not resting on a surface that could cause it to slip.

The levers used for work must be inventoried and stored in the tool room. The use of random objects as levers is prohibited.

Do not operate the power tool if it is not protected against dripping or splashing, or if it is unmarked (a drop in a triangle or two drops), or if it is exposed to dripping or splashing, or in an open area if it is snowing or raining.

If during work, a malfunction of equipment, tools, appliances and devices is detected or an employee feels even a slight tingling of the skin from the electric current, the work must be stopped immediately, and the faulty devices must be handed over for inspection and repair.

At a sudden stop of the equipment, electric tools (voltage loss, jamming of moving parts, etc.), there should be checked the insulation resistance.п.) or switching off a portable lamp, they must be disconnected from the mains.

The inventory numbers and dates of the following inspections shall be indicated on the power tool housings, and the inventory numbers and dates of the following insulation resistance measurements shall be indicated on the step-down and isolation transformers, frequency converters, and protective disconnecting devices.

Today there is a question that does not give up. Is it necessary to have a second group when working with power tools. A little bit of history. I am sitting, not disturbing anybody, the letter comes unexpectedly. Another representative of the connoisseurs of labor protection, who supports his arguments and righteousness by comprehensive experience at work, writes.

Two days before this unfortunate letter gave recommendations regarding the use of sis when testing trimmer lines. As usual, as a machine

Then there was a question, why are not specified measures in terms of training personnel in electrical safety for the second qualification group of electrical safety and not defined appropriate protective equipment (thoughts of the author: yes, galoshes, mat, gloves and diving suit). I have given the following explanations in response:

You do not test power tools class 0 and I in premises of hazardous and very dangerous for electrical safety and you do not work in electrical installations up to 1000v or more. You do not need appropriate training for group II qualification. On the first one, you should have been briefed by a responsible employee. And what PPE you want under the circumstances?

Well, here at last is the text of this unfortunate letter.

You are slightly mistaken in linking the electrical safety clearance group with the category of premises. As an example, I used to work in open pit mining (a quarry and a field. it does not smell like a room), and so. the organization management was obliged to conduct my training on electrical safety, as it threatened her with significant problems from the inspection authorities.

About electricity. I have a question not just about PPE, but about briefing and production training (if engineers don’t have an elementary understanding of electricity, as no one except me has ever had a group admission, the risk of injury increases, no one knows how to help in this case, etc.).д.). on this emphasis. the tolerance group in itself does not impose a certain list of PPE on the employee, it gives the right to perform a certain type of work (in accordance with the tolerance group) and confirms the fact that the person has an idea of safe work practices.

Everything, an explosion of brain, a mile of foul language, spilled coffee on pants This beautiful man ruined the day.

Anyway, to the point of our question, is it necessary to have a second group when working with power tools.

  • Indeed, Annex 1 of the Decree of the Ministry of Labor 28n indicates the need for a second qualification group on electrical safety at (quote)

For hand held power tools and other portable electrical equipment, etc., it is not a guarantee that they will not be subjected to overheating. д

Work with portable power tools and hand-held electric machines of classes 0 and I in high-hazard areas must only be performed by employees with group II.

Section 7.1. Class 0 electrical equipment

Section 7.2. Class I electrical equipment

  • Understanding the fact that 80% of household machines are manufactured in Class 0, to determine the class used in the work, refer to the description in the product data sheet. But this is not a verdict yet either. Consideration should be given to the conditions under which the product is used.
  • Let’s determine which rooms are classified as high-risk, to do this let’s turn to PUE (Rules for Electrical Installations), which, according to 1.1.13 Rooms with an increased risk are characterized by:

Damp or electrically conductive dust (see section 7). 1.1.8 и 1.1.11);

Conductive floors (metal, earthen, concrete, brick and T.П.);

The possibility of simultaneous human contact with the metal structures of buildings connected to the ground, technological apparatus, machinery, etc.п., on the one hand, and to metal housings of electrical equipment (exposed conductive parts) on the other;

To recapitulate all of the above. To determine whether or not employees operating electrical tools (machines

In which premises class 0 power tools may not be used

Class 0 applies to any appliance operating at voltages in excess of 42 V without grounding. Until recently, all household appliances were in this class, i.e., they were.к. These were originally designed for use in low-hazard areas. over, it is forbidden to use such class devices in constructions of the second and third class without a special housing and protective equipment. Any action on them is made by specially trained people in strict compliance with safety regulations.

To summarize, any electrical appliance should be checked for continuity before start-up, assessing the situation and surroundings judiciously, always checking the condition of outlets, and monitoring the mains voltage. It prevents many disastrous consequences, which could have been avoided by being vigilant.

How to decipher the insulation grade?

During operation of electrical appliances certain parts invariably become hot, with possible dangerous consequences, particularly if a poor-quality tool is selected. The insulation class describes the thermal stress resistance of the insulation material itself.

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

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

Classes of power tools GOST

The state standard for electrical appliance safety looks like this:

  • 0 class. characterized by the absence of earthing, implies the use of additional means of protection;
  • 01. assumes a grounding fixture;
  • 1. safety level of household and computer equipment, has a working insulation, a core in the wire, a plug “ground. contact”, and a grounding device. If wiring and ambient maintenance standards are followed, use is safe;
  • A class 2 appliance has no earthing parts and the parts are well insulated;
  • Class 3 power tools operate on a low voltage of 42 volts or less and do not require grounding.

What is considered a portable power tool?

Electric wrenches, power drills, power planners, grinders, polishers, and other electrified mechanisms not fixed on a permanent foundation, as well as electrical extension cords and portable lights are all portable power tools.

Before you enter the results of measurements and tests into the magazine, you must make these steps. Begin by assigning each power tool and portable light a serial number (according to the new rules. an inventory number), which should be written on the body with paint or permanent marker in the place that is least likely to be mechanically attacked.

Degree of safety

The safe use of a power tool is determined by its safety features. Depending on these, the requirements of the place of work, the connection of the appliance and the additional measures of protection are established.

Device classification

Classification by degree of protection against electric shock is of utmost importance when using an electric tool. The lowest classes represent the greatest danger in operation, with an increase in the index the protection against human exposure to current increases. The list of protection classes is as follows:

  • Class 0. Zero class tools are supplied with only live parts working insulation. Other non-conductive metal parts of the device, including the housing, are not insulated, so temporary or permanent human contact with areas of high electrical conductivity is possible. Devices are not designed with a protective earthing connection. This apparatus has no special indication of abnormal operation when dangerous voltage is present on the housing or other components. Zero class includes many relatively old appliances with metal enclosures which are not grounded, electric stoves and other open-circuit heating appliances, lighting devices. Most Soviet-made electrical appliances fall into this group.
  • Class 00. All specifications, except for the live housing indication, are class 0. Class 00 is not part of the official classification, but this designation is widely used. Examples of these appliances are some models of portable electric generators.
  • Class 000. The marking is also not standardized. These devices have the same characteristics as those of class zero, but with an integrated circuit-breaker. Protection parameters may vary, but in general RCDs will trip automatically if a residual current of 30mA, acting for a few hundredths of a second.
  • Class 0I. Products provided with operational insulation only. All other metallic parts are uninsulated. Protection against human exposure to electrical current is provided by earthing. Design with a separate grounding contact on the chassis. It is indicated by the traditional sign in the form of a stylized arrow consisting of one vertical and three horizontal dashes. This method requires the use of a properly sized wire, one end of which is connected to the ground terminal on the machine body and the other end is connected to the grounding connector in the electrical panel. Nowadays, it is difficult to find a tool that uses this method of grounding. However, old appliances, as well as massive machines and large electrical units often use an independent connection to the ground loop.
  • Class I. All the characteristics correspond to Class 0I, but the case and other non-current conducting metal parts are earthed in a more common way: the power cable is equipped with an additional earthing conductor which is connected to a separate contact in the plug. Such appliances should be connected only to sockets with an earthing contact. Otherwise, the use of the appliance would represent a considerable danger, and the tool itself would be classed as Class I in all respects. Examples are a washing machine, a microwave oven, a desktop computer system unit. Class 1 protection is not normally used with modern power tools.
  • Class I. The performance of the appliance is similar to Class 1, but a residual-currentoperated protective device is incorporated as an additional safety measure. This modification is rarely used, so its designation is not standardized.
  • Class II. The devices have reinforced or double insulation. Grounding of the housing of the appliance is not necessary by definition. The plug is not provided with a grounding contact. There is a common graphic symbol for such devices in the form of two squares, one nested within the other. This is the class to which most power tools belong: drills, saws, wrenches. Examples of devices in this class are also television sets, vacuum cleaners and household hair-dryers.
  • Class II. All parameters are similar to Class II, but a residual-current device has been incorporated into the appliance design. This type is quite rare, and therefore it is also not mentioned in the standardized classification. Graphical marking similar to the second class, but with a symbol in a small square
  • Class III. This group includes all devices without circuits exceeding 42 VDC or 36 VAC. Devices of this type may be marked graphically on their bodies in the form of the number III, enclosed inside a diamond. Examples include any cordless tool without high-voltage circuits: screwdrivers, drills, scissors. Among household appliances, this group includes flashlights, radios powered by batteries or rechargeable batteries. All appliances that are operated from an external power supply unit connected to a wall socket are also in Class 3.
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Using the maximum degrees of protection available is the best way to protect the operator from unexpected problems that could result if the tool should fail to operate. With improved insulation and the lack of housing components made of electrically conductive materials should not be embarrassed by the absence of grounding, since it is not necessary.

Particulars of use

The protection class of the device dictates certain requirements for operating conditions. Following these recommendations helps keep you safe from the possibility of electrical injury. Before starting work, ensure that the tool available is suitable for the conditions in which it is used. These are the basic requirements:

  • Devices of protection class zero may only be used in rooms which do not present any increased electrical hazard. This means that the inside must be dry and the floor and walls must be made of materials that do not conduct electricity. Before work is carried out, no unauthorized persons who are not involved in the production process should have access to the room.
  • In exceptional cases, Class 00 instruments can be used in humid and outdoor environments. Only specially trained staff is permitted to carry out such work. All operations may only be carried out using dielectric personal protective equipment.
  • Products of class 000 are also exceptionally authorized for operation in an electrically hazardous environment. However, their specifications already allow work to be carried out not only by specially trained personnel but also by any other person. The use of personal protective equipment against electric shock is also mandatory.
  • Class 01 devices are permitted only minor movements during operation, restricted by the length of the grounding conductor. Operation of such devices without connection to an earthing circuit is strictly prohibited.
  • Devices of class 1 may be operated without restriction. Exceptions to this rule may be specifically stated in the appliance’s instruction manual. It is permissible to connect such appliances to the mains without protective earthing, but only in rooms with a low electrical hazard. It must be remembered that in this case, all the restrictions of the zero class apply.
  • Devices of class I are used without any restrictions, but only if grounding is available. They may be operated without connection to an earthing circuit, but the employee must wear personal dielectric safety equipment.
  • Devices of the second class do not require any special operating conditions. The only exception may be the prohibition of devices with enclosure protection less than IP65 in conditions of high humidity, when it exceeds 85%.
  • Class II and III appliances are not subject to any operating conditions.

The trend nowadays is to phase out the use of class 0 devices entirely. Growing number of countries where such devices are determined to be unsafe.

Table N 7. Operating conditions for power tools and hand-held electrical machines of various classes

In the TN-S system. Without electrical protection devices when connected through a residual current device or with at least one electrical protection device. With TN-C system. With at least one electrical protection device

Without the use of electrical protection equipment

Without electrical protection equipment

With TN-S system. With at least one electrical protection device and connected with a residual current device or with only one electrical device (machine, tool) connected with a separate power supply (isolating transformer, generator, converter).

In the TN-C system. With at least one electrical protection device and with only one electrical device supplied from a separate supply

With TN-S system. Without electrical protection equipment if connected via a residual current device or if only one electrical device (machine, tool) is supplied from a separate source (isolating transformer, generator, converter). With TN-C system. With at least one electrical protection device

Without electrical protection device

No electrical protection equipment

With protection by means of a residual current device or with at least one electrical protection device

Without electrical protection equipment

Without electrical protection

When conditions are particularly unfavourable (vessels, apparatus, and other metal vessels with restricted freedom of movement and egress)

With the use of at least one electrical protection device

without using electrical protection equipment when connected via a residual current device or when only one electrical appliance is supplied from a separate source

Without electrical protection

44.4. In rooms with increased danger and especially hazardous premises portable electric lamps must have a voltage of no more than 50 V.

When working in particularly adverse conditions (switch wells, switchgear compartments, boiler drums, metal tanks) portable lights must have a voltage not exceeding 12 V.

44.5. Before working on hand-held electrical machines, portable power tools, and lighting fixtures

determine from the passport the class of the machine or tool;

Check that all components are complete and securely fastened;

make sure that the cable (cord), its protective tube and plug are in good condition, that the insulating parts of the housing, the handle and covers of the brush holders, and the protective covers are intact;

Perform (if necessary) testing of the residual current device (RCD);

check that the power tool or machine is idle;

check grounding circuits of class I machines (machine housing) are in good working order. (earthing contact of the plug).

Do not use hand-held electrical machines, portable power tools, and lighting fixtures with related auxiliary equipment that are defective and have not been periodically inspected (tested).

44.6. When using power tools, hand-held electric machines, portable lamps, their wires and cables must be suspended whenever possible.

Do not allow wires and cables to come into direct contact with hot, humid or oily surfaces or objects.

The power tool cable must be protected from accidental mechanical damage and from contact with hot, wet and oily surfaces.

It is not allowed to stretch, twist and bend the cable, put loads on it, as well as allow its intersection with cables, cables, gas-welding hoses.

If any faults are detected, work with hand-held electric machines, portable electric tools and lamps must be stopped immediately.

44.7. Hand-held electrical machines, portable electric tools and lights, auxiliary equipment issued and used at work must be accounted for in the organization (separate subdivision), inspected and tested within the time and scope established by technical regulations, national and interstate standards, technical conditions for products, the current scope and norms of testing electrical equipment and appliances of electrical installations.

To maintain the good condition, conduct periodic tests and inspections of manual electrical machines, portable power tools and lamps, auxiliary equipment, by order of the head of the organization must be assigned a responsible employee with group III.

44.8. If there is a power failure or interruption in operation, electric tools and hand-held electric machines must be unplugged from the mains.

44.9. Employees using power tools and hand-held electrical machines are prohibited:

Hand over hand-held electrical machines and power tools, even if only for a short period of time, to other workers;

disassemble hand-held electrical machines and power tools, make any repairs;

hold the wire of an electrical machine or power tool, touch rotating parts or remove chips or filings until the tool or machine has come to a complete standstill;

to install the working part in the chuck of the tool or machine and remove it from the chuck, as well as to adjust the tool without disconnecting it from the mains;

Bring portable transformers and frequency converters inside boiler drums, metal vessels.

44.10. When using an isolating transformer, the following requirements must be observed:

Only one electrical appliance may be supplied from an isolating transformer;

The secondary side of the isolating transformer must not be grounded;

The transformer body must be earthed or grounded, depending on the mode of operation of the neutral point of the power supply network. The enclosure of an electrical appliance connected to the isolating transformer need not be earthed in this case.

GENERAL HEALTH AND SAFETY REQUIREMENTS

2.1. Employees using hand-held power tools must only perform the work assigned to them by their direct supervisor.

2.2. In addition to basic protective clothing when working with power tools, the employee must be issued, and the employee must properly use personal protective equipment:

2.3. When working with power tools, it is prohibited:

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