Long-term permissible current loads for cables and wires. Electricity. Permissible values ​​of currents and voltages Monitoring of touch voltages and currents

GOST 12.1.038-82*

Group T58

INTERSTATE STANDARD

Occupational Safety Standards System

ELECTRICAL SAFETY

Maximum permissible values ​​of touch voltages and currents

Occupational safety standards system. Electric safety.
Maximum permissible values ​​of pickp voltages and currents

Date of introduction 1983-07-01

INFORMATION DATA

ENTERED INTO EFFECT by Decree of the USSR State Committee on Standards dated July 30, 1982 N 2987

The validity period was lifted according to Protocol No. 2-92 of the Interstate Council for Standardization, Metrology and Certification (IUS 2-93)

* REISSUE (June 2001) with Amendment No. 1, approved in December 1987 (IUS 4-88)

This standard establishes the maximum permissible values ​​of touch voltages and currents flowing through the human body, intended for the design of methods and means of protecting people when they interact with industrial and household electrical installations of direct and alternating current with a frequency of 50 and 400 Hz.

The terms used in the standard and their explanations are given in the appendix.

1. MAXIMUM ALLOWABLE VOLTAGE VALUES
TOUCH AND CURRENTS

1.1. Limits for touch voltages and currents are established for current paths from one hand to the other and from hand to feet.

(Changed edition, Amendment No. 1).

1.2. Touch voltages and currents flowing through the human body during normal (non-emergency) operation of an electrical installation should not exceed the values ​​indicated in Table 1.

Table 1

Variable, 50 Hz
Variable, 400 Hz
Constant

Notes:

1. Touch voltages and currents are given for a duration of exposure of no more than 10 minutes per day and are set based on the reaction of the sensation.

2. Touch voltages and currents for persons working in conditions of high temperatures (above 25 ° C) and humidity (relative humidity more than 75%) must be reduced by three times.

1.3. The maximum permissible values ​​of touch voltages and currents during emergency operation of industrial electrical installations with voltages up to 1000 V with a solidly grounded or insulated neutral and above 1000 V with an isolated neutral should not exceed the values ​​​​specified in Table 2.

table 2

Standardized value

Maximum permissible values, no more, with duration of current exposure, s

Variable

Variable

Constant

Rectified full wave

Rectified half wave

Note. The maximum permissible values ​​of touch voltages and currents flowing through the human body for a duration of exposure of more than 1 s, given in Table 2, correspond to releasing (alternating) and non-painful (direct) currents.

1.4. The maximum permissible values ​​of touch voltages during emergency operation of industrial electrical installations with a current frequency of 50 Hz, voltage above 1000 V, with solid grounding of the neutral should not exceed the values ​​​​specified in Table 3.

1.5. The maximum permissible values ​​of touch voltages and currents during emergency operation of household electrical installations with voltages up to 1000 V and a frequency of 50 Hz should not exceed the values ​​​​specified in Table 4.

Table 3

	Limit value touch voltage, V
St. 1.0 to 5.0

Table 4

Duration of exposure, s	Standardized value
From 0.01 to 0.08

Note. The values ​​of touch voltages and currents are established for people with a body weight of 15 kg.

1.3-1.5. (Changed edition, Amendment No. 1).

1.6. Human protection from the effects of touch voltages and currents is ensured by the design of electrical installations, technical methods and means of protection, organizational and technical measures in accordance with GOST 12.1.019-79.

2. CONTROL OF TOUCH VOLTAGES AND CURRENTS

2.1. To control the maximum permissible values ​​of touch voltages and currents, voltages and currents are measured in places where an electrical circuit may close through the human body. The accuracy class of measuring instruments is not lower than 2.5.

2.2. When measuring touch currents and voltages, the resistance of the human body in an electrical circuit at a frequency of 50 Hz should be modeled by a resistance resistor:

for table 1 - 6.7 kOhm;

for table 2 at exposure time

up to 0.5 s - 0.85 kOhm;

more than 0.5 s - resistance depending on voltage according to the drawing;

for table 3 - 1 kOhm;

for table 4 at exposure time

up to 1 s - 1 kOhm;

more than 1 s - 6 kOhm.

Deviation from the specified values ​​is allowed within ±10%.

2.1, 2.2. (Changed edition, Amendment No. 1).

2.3. When measuring touch voltages and currents, the resistance to the spread of current from a person’s legs should be modeled using a square metal plate measuring 25x25 cm, which is located on the surface of the earth (floor) in places where the person may be located. The load on the metal plate must be created by a mass of at least 50 kg.

2.4. When measuring touch voltages and currents in electrical installations, modes and conditions must be established that create the highest values ​​of touch voltages and currents affecting the human body.

APPENDIX (reference). TERMS AND THEIR EXPLANATIONS

APPLICATION
Information

	Explanation
Touch voltage	According to GOST 12.1.009-76
Electrical installation emergency mode	Operation of a faulty electrical installation, in which dangerous situations may arise leading to electrical injury to people interacting with the electrical installation
Household electrical installations	Electrical installations used in residential, municipal and public buildings of all types, for example, in cinemas, cinemas, clubs, schools, kindergartens, shops, hospitals, etc., with which both adults and children can interact
Release current	Electric current that does not cause irresistible convulsive contractions of the muscles of the hand in which the conductor is clamped when passing through the human body

(Changed edition, Amendment No. 1).

The text of the document is verified according to:
official publication
System of occupational safety standards: Sat. GOST. -
M.: IPK Standards Publishing House, 2001

Our modern life is full of a variety of household appliances and devices that make our life much easier, making it more and more comfortable, but at the same time a whole complex of dangerous, harmful factors appears: electromagnetic fields of various frequencies, increased levels of radiation, noise, vibration, danger of mechanical injury, the presence of toxic substances, as well as, most importantly, electric current.

Electric current is the ordered movement of electrical particles. For your own safety, you need to know the effect of electric current on the human body, measures to protect against electric shock, and providing assistance to a person injured by electric current.

Effects of electric current on the human body

Electric current has biological, thermal, and electrolytic effects on humans.

Thermal: heating of tissues when electric current flows through them.

Electrolytic: decomposition of blood and other body fluids.

Biological: excitation of living tissues of the body, accompanied by convulsions, muscle spasms, cardiac activity, and respiratory arrest.

When a person is exposed to an electric current, bodily electrical injuries occur: burns, electrical marks, metallization of the skin, mechanical damage, blinding by the light of an electric arc, or an electric shock may occur - this is a general damage to the body, which can be accompanied by convulsions, loss of consciousness, respiratory and cardiac arrest , and even clinical death.

Electrical signs- these are gray and pale yellow spots, bruises, scratches on human skin that have been exposed to electric current. The strength of the sign corresponds to the strength of the live part touched by the person. In most cases, treatment of electrical signs ends successfully, and the affected area is completely restored.

Mechanical damage occur under the influence of electric current when muscles involuntarily contract convulsively. Mechanical injuries (bone fractures, ruptures of blood vessels, skin) are injuries that require long-term treatment.

Electric shock. From time to time, there are cases when children, out of curiosity, stick their fingers into an electrical outlet or start poking at it with a nail, wire or other metal objects. Most often this happens to children under three years of age. There are cases when children receive an electric shock from live wires falling to the ground. When exposed to electric current, an involuntary muscle contraction may occur, preventing the child from tearing away from the current source. An electrical burn occurs at the point of contact with current. In severe cases, respiratory and cardiac dysfunction occurs. The first thing to do is to free the child from the electric current. The safest thing is to quickly remove the plugs if an accident occurs in the house. If for some reason this cannot be done, then you need to throw a rubber mat, board or thick cloth under your feet, or put rubber boots or galoshes on your feet; You can put household rubber gloves on your hands. Pull the victim away from the wire, grabbing his clothes with one hand. You can also try to move the victim himself away from the current source or remove the source from him. This must be done with one hand, so that even if you receive a shock, the current does not pass through the entire body of the person providing assistance. The victim must be laid down, covered warmly, freed from restrictive clothing, and, if possible, given a warm drink. A sterile bandage made of a bandage or clean cloth should be applied to the area of ​​the body burned by electric current, after moistening it in alcohol or vodka. If the child has lost consciousness, they give him ammonia to sniff and splash cold water on his face. If a child lies unconscious and is not breathing, but has a pulse, it is necessary to immediately give him artificial respiration using the mouth-to-mouth method. To do this, tilt the child’s head back and, pinching his nostrils, blow air into his mouth in portions, placing his lips on the child’s lips.

Electrical burn different degrees - the result of short circuits in electrical installations and the presence of the body (hands) in the environment of the light and thermal influence of the electric arc; third and fourth degree burns with a severe outcome - when a person comes into contact with parts through which a current of voltage over 1000 V passes.

Metallization of leather These are tiny particles of metal that penetrate into the upper layers of the skin, melted under the action of an electric arc or dissolved in the electrolytes of electrolysis baths. In the affected area, the skin becomes hard, rough and acquires the color of metal (for example, green - from contact with copper). Work involving the possibility of an electric arc should be done with glasses, and the worker's clothing should be buttoned up.

Current strength, mA	Alternating current	Direct current
	Sensation of current flow Fingers tremble (slightly)	Not felt
	Fingers are shaking (very much)	Not felt
	Cramps in the hands	Itching. Warming sensation
	The hands are immediately paralyzed, it is impossible to tear them away from the electrodes, the pain is very severe. Breathing is difficult	Heating increases even more, slight contraction of the arm muscles
	Respiratory paralysis. The ventricles of the heart begin to flutter	Strong feeling of heating. Contraction of arm muscles. Cramps. Difficulty breathing.
	Heart fibrillation	Respiratory paralysis

Electroophthalmia is an ultraviolet ray (the source of which is a voltaic arc, it affects the eye). As a result of electroophthalmia, an inflammatory process occurs, and if the necessary treatment measures are taken, the pain goes away.

Depending on the magnitude of the current, its voltage, frequency, duration of exposure, the path of the current and the general condition of the person, the outcome of the action of the electric current on the human body depends. It has been established that a current of more than 0.05 A can fatally injure a person within 0.1 s. The largest number of injuries from electric current (about 85%) occurs in installations with voltages up to 1000 V. Alternating and direct current are dangerous for the human body. The most dangerous is alternating current with a frequency of 20-100 Hz; and the frequency of 400 Hz is not so dangerous. Voltage up to 12 V can be considered practically safe for humans in damp rooms, and up to 36 V in dry rooms. The probability of electric shock to a person depends on the climatic conditions in the room (temperature, humidity), as well as conductive dust, metal structures connected to the ground , conductive floor, etc.

In accordance with the “Rules for the Construction of Consumer Electrical Installations” (PUE), all premises are divided into three classes:

without increased danger - not hot (up to +35°C), dry (up to 60%), dust-free, with a non-conductive floor, not cluttered with equipment;

with increased danger - have at least one factor of increased danger, i.e. hot or humid (up to 75%), dusty, with a conductive floor, etc.;

especially dangerous - have two or more high-risk factors or at least one special danger factor, i.e. special dampness (up to 100%) or the presence of a chemically active environment.

Possible values ​​of contact currents and voltages depending on the protection response time are specified in GOST 12.1.038-88. According to this document, for normal (non-emergency) operation of industrial equipment, permissible touch voltages should not exceed 2 V at a current frequency of 50 Hz, 3 V at 400 Hz and 8 V for direct current, but the total duration of exposure should not exceed 10 minutes per day. In normal operation of household equipment, the presence of touch voltages is not allowed. In particularly dangerous (or with increased danger) premises, all equipment must be grounded with a supply voltage above 42 V AC and 10 V DC. In normal premises, all equipment is rated at 380V or higher AC and 440V or higher DC. All equipment, regardless of supply voltage, is grounded only in explosive areas.

As the duration of exposure to electric current increases, the risk of injury increases. After 30 sec. The resistance of the human body to the flow of current drops by about 25% after 90 seconds. by 70%. The human body's resistance to electric current varies over a wide range. Dry, rough, calloused skin, lack of fatigue and a normal state of the nervous system increase the resistance of the human body. Nerve fibers and muscles have the least resistance. The minimum calculated resistance of the human body is taken to be from 500 to 1000 Ohms.

At the moment when a person closes two phase wires of an operating installation with his body, he comes under the full linear voltage of the network. Taking into account that the calculated resistance of the human body is assumed to be 1000 Ohms, then a two-phase touch to the active parts of the installation, the voltage of which is 100 V, can be fatal due to the fact that the current passing through the human body reaches a value of 0.1 A .

If a current of 0.06 A or more passes through a person's body, an electric shock occurs. Human resistance to electric current is variable. It depends on many factors, including the psychological state and physical condition of the person. The average resistance value is within the range of 20-100 kOhm. It can drop to 1 kOhm under particularly unfavorable conditions. In this case, a voltage of 100 V or lower will be dangerous to human life.

The amount of current passing through the human body depends on its resistance. And resistance depends mainly on the condition of a person’s skin. The resistance of the human body also depends on the frequency of the current. The calculated value of the body's electrical resistance is taken to be 1.0 kOhm. At current frequencies of 6-15 kHz it is the smallest.

Direct current is less dangerous than alternating current. Direct current up to 6 mA is almost imperceptible. At a current of 20 mA, cramps appear in the muscles of the forearm. Alternating current begins to be felt already at 0.8 mA. A current of 15 mA causes contraction of the arm muscles. Particularly dangerous is the passage of current through the heart.

The risk of injury from direct and alternating current varies with increasing voltage. At voltages up to 220 V, alternating current is more dangerous, and at voltages above 500 V, direct current is more dangerous. The more current flows, the lower the resistance of the human body becomes. Death may occur if the electrical current is not interrupted. If the current passes from the hand to the feet, then what kind of shoes a person is wearing, what material they are made of, and what quality they are of significant importance. The degree of damage is also significantly influenced by the resistance at the point of contact of a person with the ground. Electric current has serious consequences, including cardiac arrest and cessation of breathing. Therefore, you need to be able to provide first aid to a victim of electric shock.

Static electricity – this is a potential supply of electrical energy generated on equipment as a result of friction and the inductive influence of strong electrical discharges. In rooms with a large amount of dust of organic origin, static discharges can form and also accumulate on people when using linen and clothing made of lye, wool and artificial fibers, when moving on a non-conductive synthetic floor covering such as linoleum, carpet, etc.

The electrostatic field is regulated in accordance with GOST 12.1.045-84; the electric field strength at workplaces should not exceed 60 kV/m for an hour. The residence time in an electric field at 20≤E≤60 (kV) is calculated by the formula t=(60/E)2, where E is the actual value of the field strength. The resistance of grounding devices for protection against static electricity should not exceed 100 (ohms).

Depending on the duration of exposure to a person

table 2

Type of current	Standardized value.	Duration of current exposure t,s
0,01-0,08	0,1	0,2	0,3	0,4	0,5	0,6	0,7	0,8	0,9	1,0
Variable (50Hz)	I
U
Constant	I
U

The permissible values ​​of touch voltage and current passing through the human body are used to develop a set of protective measures and determine the parameters of protective devices at which it is still possible to ensure safety. Sometimes the term “safe current” is used, which has no meaning, since a current of any magnitude has some effect on the human body. Yes, electric current 0.02 - 0.07mA, 50 Hz causes pain in certain points on the human body. Therefore, it is legitimate to use the concept of “permissible current”. The permissible current value should be set based on those threshold current values ​​at which a real danger appears. Thus, in hazardous working conditions (altitude, near moving or rotating parts, etc.), when a person during work is forced to have constant contact with live parts, the long-term permissible current should be taken below the sensation threshold, no more 0.5mA. When working under normal (safe) conditions, the non-permissible current threshold should be taken as the long-term permissible current in case of accidental contact, 10mA, since exceeding this current value poses a real danger.

Current frequency

It has been established that the resistance of the human body also includes a capacitive component:

Therefore, an increase in the frequency of the applied voltage is accompanied by a decrease in the total resistance of the body and an increase in the current passing through the person. With an increase in the current passing through the human body, the danger of injury increases, which means that an increase in frequency should lead to an increase in such danger.

However, this assumption is valid only in the frequency range from 0 before 50 Hz. In the frequency range from 0 before 50 Hz with decreasing frequency, the value of the non-releasing current increases and at a frequency equal to zero (direct current), it becomes approximately 3 times larger (see Fig. 2).

An increase in frequency above this range, despite an increase in the current passing through the human body, is accompanied by a decrease in the danger of injury, which completely disappears at a frequency 450-500 kHz, i.e. such currents cannot affect a person. However, in this case, the danger of burns remains when current passes through the human body and when an electric arc occurs.

The risk of injury is taken to be the reciprocal of the non-releasing current at a given frequency, expressed as a percentage. The danger at 50 Hz as the highest in the entire frequency scale.

Then the danger of injury at the desired frequency is determined from the expression

where, are non-releasing currents at 50 Hz and the desired frequency f, mA.

In a simplified way, the change in the danger of current with a change in frequency can be explained by the nature of the irritating effect of the current on the cells of living tissue.

If a constant voltage is applied to a living tissue cell, then electrolytic dissociation occurs in the intracellular substance, which can be considered as an electrolyte, resulting in the breakdown of molecules into positive and negative ions. These ions will begin to move to the cell membrane, positive ions to the negative electrode, and negative ions to the positive electrode. This phenomenon will cause a disruption in the normal state of the cell and the natural biochemical processes occurring in it.

With alternating current, ions will move following the change in polarity of the electrodes.

It can be assumed that in the frequency range from 0 before 50 Hz, a greater disruption of the natural state of the cell is caused by a current in which the ion makes from one to several “full” runs per unit of time inside the cell membrane. Presumably, either one “full” path of ions, or the maximum number of “full” paths that occur at a frequency 50 Hz. Since ions, as material particles, have a certain speed of movement in the electrolyte, then at a certain frequency (obviously 50 Hz) the ion will not have time to reach the cell membrane during the polarity change. This position will presumably correspond to less disruption of the normal state of the cell. With a further increase in frequency, the travel distance of the ions will decrease and a moment may come when the movement of the ions stops, and therefore there will be no dangerous disruption to the state of the cell. This situation occurs at frequencies higher 450-500 kHz.

Current paths

In the practice of operating electrical installations, when a person is connected to an electrical circuit, current flows through him, as a rule, along the “arm-to-leg” or “arm-to-arm” path. However, there are many possible current paths in the human body. The degree of damage in these cases depends on which vital organs (heart, lungs, brain) of a person are affected by the current, as well as on the magnitude of the current directly affecting these organs and in particular the heart.

Typical current paths (current loops) in the human body are shown in Fig. 3.

The current is distributed throughout the body, but most of it passes along the path of least resistance - along the blood and lymph vessels, nerve trunks and branches.

In this case, the path of least resistance does not have to be the shortest between the electrodes. Measurements have shown that the value of the human body’s resistance to electric current is different for different current loops:

- "hand - hand" – 1360 Ohm;

- "arm - legs" – 970 Ohm;

- "hands-legs" - 670 Ohm.

The danger of various current loops can be assessed using the data in Table 3.

The most dangerous loops are head - arms, head - legs, when the current can pass through the brain and spinal cord. However, these loops occur relatively rarely. The next most dangerous path is the right arm - legs, when the greatest current flows through the heart along the longitudinal axis.

Despite the small amount of current flowing through human hearts during a leg-to-leg loop at a step voltage equal to 80-120 V, leg muscle spasms occur, the person falls and, touching the ground with his hand, comes under high voltage, since the current loop will now be “arms - legs” (“arm – leg”), which can lead to electric shock.

Permissible long-term currents for wires with rubber or polyvinyl chloride insulation, cords with rubber insulation and cables with rubber or plastic insulation in lead, polyvinyl chloride and rubber sheaths are given in Table. 1.3.4-1.3.11. They are accepted for temperatures: cores +65, ambient air +25 and ground + 15°C.

When determining the number of wires laid in one pipe (or cores of a stranded conductor), the neutral working conductor of a four-wire three-phase current system, as well as grounding and neutral protective conductors are not taken into account.

Permissible long-term currents for wires and cables laid in boxes, as well as in trays in bundles, must be accepted: for wires - according to table. 1.3.4 and 1.3.5 as for wires laid in pipes, for cables - according to table. 1.3.6-1.3.8 as for cables laid in the air. If the number of simultaneously loaded wires is more than four, laid in pipes, boxes, and also in trays in bundles, the currents for the wires should be taken according to the table. 1.3.4 and 1.3.5 as for wires laid openly (in the air), with the introduction of reduction factors of 0.68 for 5 and 6; 0.63 for 7-9 and 0.6 for 10-12 conductors.

For secondary circuit wires, reduction factors are not introduced.

Table 1.3.4. Permissible continuous current for wires and cords with rubber and polyvinyl chloride insulation with copper conductors

	Current, A, for wires laid in one pipe
	open	two single-core	three single-core	four single-core	one two-wire	one three-wire
0,5	11	-	-	-	-	-
0,75	15	-	-	-	-	-
1	17	16	15	14	15	14
1,2	20	18	16	15	16	14,5
1,5	23	19	17	16	18	15
2	26	24	22	20	23	19
2,5	30	27	25	25	25	21
3	34	32	28	26	28	24
4	41	38	35	30	32	27
5	46	42	39	34	37	31
6	50	46	42	40	40	34
8	62	54	51	46	48	43
10	80	70	60	50	55	50
16	100	85	80	75	80	70
25	140	115	100	90	100	85
35	170	135	125	115	125	100
50	215	185	170	150	160	135
70	270	225	210	185	195	175
95	330	275	255	225	245	215
120	385	315	290	260	295	250
150	440	360	330	-	-	-
185	510	-	-	-	-	-
240	605	-	-	-	-	-
300	695	-	-	-	-	-
400	830	-	-	-	-	-

Table 1.3.5. Permissible continuous current for rubber and polyvinyl chloride insulated wires with aluminum conductors

Cross-section of current-carrying conductor, mm 2	Current, A, for wires laid in one pipe
	open	two single-core	three single-core	four single-core	one two-wire	one three-wire
2	21	19	18	15	17	14
2,5	24	20	19	19	19	16
3	27	24	22	21	22	18
4	32	28	28	23	25	21
5	36	32	30	27	28	24
6	39	36	32	30	31	26
8	46	43	40	37	38	32
10	60	50	47	39	42	38
16	75	60	60	55	60	55
25	105	85	80	70	75	65
35	130	100	95	85	95	75
50	165	140	130	120	125	105
70	210	175	165	140	150	135
95	255	215	200	175	190	165
120	295	245	220	200	230	190
150	340	275	255	-	-	-
185	390	-	-	-	-	-
240	465	-	-	-	-	-
300	535	-	-	-	-	-
400	645	-	-	-	-	-

Table 1.3.6. Permissible continuous current for wires with copper conductors with rubber insulation in metal protective sheaths and cables with copper conductors with rubber insulation in lead, polyvinyl chloride, nayrite or rubber sheaths, armored and unarmored

	Current *, A, for wires and cables
	single-core	two-wire		three-wire
	when laying
	in the air	in the air	in the ground	in the air	in the ground
1,5	23	19	33	19	27
2,5	30	27	44	25	38
4	41	38	55	35	49
6	50	50	70	42	60
10	80	70	105	55	90
16	100	90	135	75	115
25	140	115	175	95	150
35	170	140	210	120	180
50	215	175	265	145	225
70	270	215	320	180	275
95	325	260	385	220	330
120	385	300	445	260	385
150	440	350	505	305	435
185	510	405	570	350	500
240	605	-	-	-	-
* Currents apply to wires and cables both with and without a neutral core.

Table 1.3.7. Permissible continuous current for cables with aluminum conductors with rubber or plastic insulation in lead, polyvinyl chloride and rubber sheaths, armored and unarmored

Conductor cross-section, mm2	Current, A, for cables
	single-core	two-wire		three-wire
	when laying
	in the air	in the air	in the ground	in the air	in the ground
2,5	23	21	34	19	29
4	31	29	42	27	38
6	38	38	55	32	46
10	60	55	80	42	70
16	75	70	105	60	90
25	105	90	135	75	115
35	130	105	160	90	140
50	165	135	205	110	175
70	210	165	245	140	210
95	250	200	295	170	255
120	295	230	340	200	295
150	340	270	390	235	335
185	390	310	440	270	385
240	465	-	-	-	-

Note. Permissible continuous currents for four-core cables with plastic insulation for voltages up to 1 kV can be selected according to table. 1.3.7, as for three-core cables, but with a coefficient of 0.92.

Table 1.3.8. Permissible continuous current for portable light and medium hose cords, portable heavy duty hose cables, mine flexible hose cables, floodlight cables and portable wires with copper conductors

Conductor cross-section, mm2	Current *, A, for cords, wires and cables
	single-core	two-wire	three-wire
0,5	-	12	-
0,75	-	16	14
1,0	-	18	16
1,5	-	23	20
2,5	40	33	28
4	50	43	36
6	. 65	55	45
10	90	75	60
16	120	95	80
25	160	125	105
35	190	150	130
50	235	185	160
70	290	235	200

________________

* Currents apply to cords, wires and cables with and without a neutral core.

Table 1.3.9. Permissible continuous current for portable hose cables with copper conductors and rubber insulation for peat enterprises

__________________

Table 1.3.10. Permissible continuous current for hose cables with copper conductors and rubber insulation for mobile electrical receivers

__________________

* Currents refer to cables with and without a neutral core.

Table 1.3.11. Permissible continuous current for wires with copper conductors with rubber insulation for electrified transport 1.3 and 4 kV

Conductor cross-section, mm 2	Current, A	Conductor cross-section, mm 2	Current, A	Conductor cross-section, mm 2	Current, A
1	20	16	115	120	390
1,5	25	25	150	150	445
2,5	40	35	185	185	505
4	50	50	230	240	590
6	65	70	285	300	670
10	90	95	340	350	745

Table 1.3.12. Reduction factor for wires and cables laid in boxes

Laying method	Number of laid wires and cables		Reducing factor for wires supplying groups of electrical receivers and individual receivers with a utilization factor of more than 0.7
	single-core	stranded	separate electrical receivers with a utilization factor of up to 0.7	groups of electrical receivers and individual receivers with a utilization factor of more than 0.7
Multilayered and in bunches. . .	-	Up to 4	1,0	-
	2	5-6	0,85	-
	3-9	7-9	0,75	-
	10-11	10-11	0,7	-
	12-14	12-14	0,65	-
	15-18	15-18	0,6	-
Single layer	2-4	2-4	-	0,67
	5	5	-	0,6

1.3.11

Permissible long-term currents for wires laid in trays, when laid single-row (not in bundles), should be taken as for wires laid in the air.

Permissible long-term currents for wires and cables laid in boxes should be taken according to table. 1.3.4-1.3.7 as for single wires and cables laid openly (in the air), using the reduction factors indicated in table. 1.3.12.

When choosing reduction factors, control and reserve wires and cables are not taken into account.

1. Maximum permissible values ​​of touch voltages and currents

1.1. Limits for touch voltages and currents are established for current paths from one hand to the other and from hand to feet.

(Changed edition, Amendment No. 1).

1.2. Touch voltages and currents flowing through the human body during normal (non-emergency) operation of an electrical installation should not exceed the values ​​indicated in table. 1 .

Table 1

Notes:

1. Touch voltages and currents are given for a duration of exposure of no more than 10 minutes per day and are set based on the reaction of the sensation.

2. Touch voltages and currents for persons working in conditions of high temperatures (above 25°C) and humidity (relative humidity more than 75%) must be reduced by three times.

1.3. The maximum permissible values ​​of touch voltages and currents during emergency operation of industrial electrical installations with voltages up to 1000 V with a solidly grounded or insulated neutral and above 1000 V with an isolated neutral should not exceed the values ​​​​specified in table. 2.

table 2

Type of current	Normalize May magnitude	Maximum permissible values, no more, for the duration of exposure to current t, s
		0,01- 0,08	0,1	0,2	0,3	0,4	0,5	0,6	0,7	0,8	0,9	1,0	St. 1,0
Variable 50 Hz	U, V I, mA	550 650	340 400	160 190	135 160	120 140	105 125	95 105	85 90	75 75	70 65	60 50	20 6
Variable 400 Hz	U, V I, mA	650	500	500	330	250	200	170	140	130	110	100	36 8
Constant	U, V I, mA	650	500	400	350	300	250	240	230	220	210	200	40 15
Rectified full-wave	U_ampl, V I_ampl, mA	650	500	400	300	270	230	220	210	200	190	180	-
Rectified half-wave	U_ampl, V I_ampl, mA	650	500	400	300	250	200	190	180	170	160	150	-

Note. The maximum permissible values ​​of touch voltages and currents flowing through the human body with a duration of exposure of more than 1 s, given in table. 2 correspond to releasing (alternating) and non-painful (direct) currents.

1.4. The maximum permissible values ​​of touch voltages during emergency operation of industrial electrical installations with a current frequency of 50 Hz, voltage above 1000 V, with solid grounding of the neutral should not exceed the values ​​​​specified in table. 3.

Table 3

1.5. The maximum permissible values ​​of touch voltages and currents during emergency operation of household electrical installations with voltages up to 1000 V and a frequency of 50 Hz should not exceed the values ​​​​specified in table. 4 .

Table 4

Note. The values ​​of touch voltages and currents are established for people with a body weight of 15 kg.

1.3-1.5. (Changed edition, Amendment No. 1).

1.6. Protection of a person from the effects of touch voltages and currents is ensured by the design of electrical installations, technical methods and means of protection, organizational and technical measures for