U S S R S T A T E S T A N D A R D

UNIFIED SYSTEM OF DESIGN DOCUMENTATION

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CONVENTIONS OF WIRES AND TERMINAL
CONNECTIONS OF ELECTRICAL ELEMENTS,
EQUIPMENT AND SUBCIRCUITS IN CIRCUIT DIAGRAMS
GOST 2.709-89
(CMEA Standard 3754-82, CMEA Standard 6308-88)

Official Edition

USSR STATE COMMITTEE FOR STANDARDS

Moscow

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 UDC 621.332.35 : 621.215.68 : 006.354 Group T5

U S S R S T A T E S T A N D A R D

NIFIED SYSTEM OF DESIGN DOCUMENTATION GOST

2.709-89
CONVENTIONS OF WIRES AND TERMINAL
CONNECTIONS OF ELECTRICAL ELEMENTS, (CMEA Standard 3754-82,
EQUIPMENT AND SUBCIRCUITS IN CIRCUIT CMEA standard 6308-88)
DIAGRAMS

OKSTU 0002

Date of introduction 01.01.90

This Standard applies to circuit diagrams for products of all industry and
construction branches and establishes the conventions of wires and terminal clamps
(hereinafter referred to as clamps) of electrical elements, devices, equipment, basic
electrical elements (resistors, safety fuses, relays, transformers, rotating machines),
engine control devices, feeding, earthing, connection with framework, subcircuits in
circuit diagrams.

1. GENERAL PROVISIONS

1.1. This Standard establishes the methods of distinction the clamps, and also the
general rules for their unified designation.

N o t e . The term "designation of clamps" is applied for designation of conducting subcircuits and
electrical elements, designed for connection.

1.2. The unified method of designation may be used for computer application and for
teletype information transfer.
1.3. The drawings in this Standard are given as examples for text illustration.

Official Edition Reprinting is prohibited

*
© Standards Publishing House, 1989
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2. DESIGNATION METHODS

2.1. The function and arrangement of clamps are important criteria for the choice of
a method of their designation.
The distinctive features of designation methods are as follows:
1) arrangement of clamps in accordance with the chosen system;
2) conventional color in accordance with the selected system;
3) conventional graphical symbols in accordance with GOST 2.721;
4) alphanumerical symbols in accordance with Section 4.
N o t e. The above specified methods are equivalent from the standpoint of their utilization.

The using of graphical symbols in accordance with GOST 2.721 is allowed instead
of alphanumerical ones (see tables 1 and 2).
2.2. The choice of a designation method depends on the kind of device, clamps
arrangement and complexity of device or wiring.
2.3. The alphanumerical symbols shall be used for complicated devices and wiring
and are suitable for teletype transfer.

3. UTILIZATION OF DESIGNATION

3.1. The conventional color, the appropriate graphical or alphanumerical symbols

shall be used for designation of electrical elements.
3.2. In case of using of conventional color for clamps’ designation, the interrelation
between the color and the equivalent graphical or alphanumerical symbols shall be
indicated in accompanying documentation.
3.3. If the structure of a certain element or device does not allow to designate a
clamp, then the accompanying documentation shall specify the relation between the
clamps’ arrangement by equivalent graphical or alphanumeric symbols, and also the
positional relationship of clamps.

4. UNIFIED SYSTEM OF ALPHANUMERIC SYMBOLS FOR

WIRES AND CLAMPS

4.1. The capital Latin letters and Arabic numerals shall be used for construction of
alphanumeric symbols. The application of I and O letters is not recommended.
4.2. The full designation consists of groups, and each group consists of letters and
(or) numerals.
The omitting of one or several groups is allowed, if it does not result in error during
connecting.
The dot shall be used for separating of groups, consisting of numerals or letters only.
The dot may be omitted if there is no necessity to differentiate the subsequent groups.

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 p.3 GOST 2.709-89

For example, the full designation 1U11 may be written as 1.11 if there is no
necessity to indicate group U; the dot may be omitted if there is no necessity to
differentiate the subsequent groups: 111.
4.3. The using of symbols “+” and “−” is allowed for teletype transfer.
Designation principles
4.4. The following principles are observed in designation system.
Two end points of elements shall be designated by successive numerals (for
example, 1 and 2 on fig. 1).
The via points of a simple element shall be preferably designated by consequent
numerals (3, 4, 5 etc.).
The via points numbering shall be started from the end point, designated by a
smaller number. For example, the via points of an element with terminal clamps 1 and 2
shall be designated by numerals 3, 4, 5 as it is shown on fig. 2.

Fig. 1. Fig. 2.

4.5. When several identical elements are connected in groups, the endings of these
elements shall be designated by the following way:
1) the letters (for example, U, V, W) shall be placed before the numerals according
to clause 4.4 in accordance with phases of three-phase system (fig. 3a);
2) the consequent numeral shall be placed before numerals according to clause 4.4 if
it not necessary or not possible to distinct phases. For example, the endings of one
element are designated as 1.1 and 1.2, and the same endings of the following element are
designated as 2.1 and 2.2, if it does not result in substitution of designation 11, 12 and 21,
22 (fig. 3б).

Fig. 3.

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 p. 4 GOST 2.709-89

4.6. The similar groups of elements, whose endings within these groups are
designated in accordance with clause 4.5, are distinguished by placing the order numbers
of groups before these designations according to fig. 4.

Fig. 4.

The letter symbols of clamps for direct-current elements shall be preferably selected
from the first half of Latin alphabet, and for alternating-current elements they shall be
preferably selected from the second half of the alphabet.
N o t e. An example of application of alphanumeric symbols of wires and clamps in three-phase
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system is specified on fig. 5.

Supply
line

Electric
device

End user

Fig. 5.

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 p. 5 GOST 2.709-89

The clamps’ symbols of electric devices, connected to special wires, are specified in
tab. 1.
Table 1
Circuit terminals of electrical device Symbol
alphanumeric graphical
For alternating current:
1st phase U
2nd phase V
3rd phase W
neutral wire N
Protective wire PE In accordance with GOST 2.721
Earthing wire E »
Noiseless earthing wire TE »
Wire of connection with framework MM »
Equipotential wire СС »

The clamps of electrical devices, designed for direct or indirect connection with
supply wires of three-phase system, shall be preferably designated by letters U, V and W,
if the observing of the phases succession is necessary.
The clamp, connected with a framework, shall be designated by letters MM, the
equipotential clamp shall be designated as СС. This designation shall be used only in case
when the connection of this clamp with protective wire or with the earth is invisible.
4.7. The symbols of wires of special type are specified in tab. 2.

Table 2
Symbol
Name alphanumeric graphical

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Alternating-current feed system:
phase wire L
1st phase L
2nd phase L2
3rd phase L3
neutral wire N
Direct-current supply system:
positive pole L+ +
negative pole L_ _

middle wire M

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 p. 6 GOST 2.709-89

Symbol
Name alphanumeric graphical
Earthed protective wire РЕ In accordance with GOST 2.721
Unearthed protective wire PU »
Connected protective and middle wire PEN »
Earthing wire N »
Noiseless earthing wire TE »
Wire of connection with framework MM »
Equipotential wire CC »

5. SUBCIRCUIT DESIGNATIONS

5.1. The designation of subcircuits serves for their identification, it may reflect their

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functionality and creates a connection between the circuit diagram and the device.
5.2. The capital Latin letters and Arabic numerals, both of the same typesize, shall
be used for designation.
5.3. The subcircuits, separated by device contacts, machine windings, resistors and
other elements, shall have different designations.
5.4. The clamps, passing through nonseparable, collapsible and detachable contact
clamps, shall be designated similarly. The usage of different designations in justified
cases is allowed.
5.5. The subcircuits in diagrams shall be designated irrespective of numbering of
input and output terminals of machines and devices.
5.6. The sequence of a designation shall be generally from the input (power source)
to the end user. The branching circuits shall be designated top-down in the direction from
left to right.
When designating the subcircuits, for convenient orientation in diagrams it shall be
allowed to leave the reserve numbers or to miss some numbers.
5.7. The designation of alternating-current circuit consists of phase subcircuits
designations and sequential number.
For example, subcircuits of the 1-st phase - L1, L11, L12, L13, etc.,
2-nd phase - L2, L21, L22, L23, etc.,
3-rd phase - L3, L31, L32, L33, etc.

An example of designation is specified on fig. 6. The designation abridgement in

accordance with clause 4.2 is allowed.
The phase designation with aid of letters A, B, C respectively is allowed provided
that it does not lead to a wrong connection.
5.8. The sequential numerals shall be applied for distinction of phase wires or
polarity, relating to different consumers. These numerals shall be placed before the
designation of the given phase or polarity (for example, designation 2L1 means a wire of
the first phase leading to the second consumer).

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Fig. 6

5.9. It is allowed to designate the subcircuits by sequential numerals, as it is shown

on fig. 7.
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Fig. 7.

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 p. 8 GOST 2.709-89

5.10. Direct-current circuits on positive polarity sites shall be designated by odd

numerals, and on negative polarity sites they shall be designated by even numerals. The
input and output subcircuits shall be designated with polarity indication “L+” and “L−”;
the application of signs “+” or “−” is only allowed (fig. 8).

Fig. 8.

5.11. It is allowed to include the phases designation into control, protective,

signaling, automation and measuring circuit designations (fig. 9).
The designation of subcircuits with even and odd numerals in single-phase and
double-phase non-power circuits of alternating current is allowed.
It is allowed to include the designation, characterizing the circuit functionality, into
the circuit designation. In this case it is allowed to set the sequence of numerals within
the limits of the functional circuit.

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Fig. 9.

5.12. The usage of a capital Latin letter (except for A, B, C and M), which is chosen
for circuits designation of the given device, is allowed for designation of circuits of the
separate device, included in the article. In this case the setting of numerals sequence is
allowed within the limits of the device.
5.13. On a diagram the designation shall be affixed near the endings or in the middle
of a subcircuit: at the left of the circuit image - for vertical circuit arrangement, and above
the circuit image - for horizontal circuit arrangement.
In technically justified cases it is allowed to affix the designations above the circuit
image.

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 p. 9 GOST 2.709-89

5.14. The addresses of subcircuit connections may be used as designations. In this

case the connection address of subcircuit end shall be indicated near the subcircuit
beginning, and the connection address of subcircuit biginning shall be indicated near its
end. The alphanumeric symbols of an element, device or functional group are used as the
addresses in accordance with GOST 2.710 (figs. 10 and 11).
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Fig. 10 Fig. 11

The application of combined designation, consisting of circuit and connection

addresses indications, is allowed (fig. 12).

Fig. 12

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 p. 10 GOST 2.709-89

DETAILS

1. DEVELOPED AND SUBMITTED by the USSR State Committee for Standards

DEVELOPERS
S. S. Borushek; V.V .Gugnina; B. Ya. Kabakov; B. S. Mendrikov; S. L. Taller; N. K.
Tokareva; P. A. Shalayev, Cand. Sci. (Tech.).

2. APPROVED AND INTRODUCED by Decree No. 669, dated 24.03.89, of the

USSR State Committee for Standards

3. This Standard fully complies with CMEA Standard 3754-72 and CMEA Standard
6308-88

4. In place of GOST 2.709-72

5. REFERENCE DOCUMENTATION

Number of reference document referred to Clause number

GOST 2.721-74 2.1, 4.6, 4.7

GOST 2.710-81 5.14

Editor V. P. Ogurtsov
Technical Editor L. A. Nikitina
Proof-reader O. Yu. Afanasyeva
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