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GB/T 24612.2-2009 (GB/T24612.2-2009)

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GB/T 24612.2-2009: PDF in English (GBT 24612.2-2009)
GB/T 24612.2-2009
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
lCS 29.030
K 09
Requirements for Electrical Safety in the Workplace -
Part 2. Safety Measure of Operation on Power off
ISSUED ON. NOVEMBER 15, 2009
IMPLEMENTED ON. MAY 01, 2010
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative References ... 4 
3 Terms and Definitions ... 4 
4 Procedure of Safe power-off Operation ... 5 
5 Lockout and Tagout for Disconnected Charged Body and Circuit Parts when
Working on or nearby them ... 6 
5.1 General ... 6 
5.2 Principle of Lockout and Tagout Operation ... 6 
5.3 Working Responsibility ... 7 
5.4 Control of Electric Shock Prevention ... 8 
5.5 Devices ... 10 
6 Temporary Protective Earthing Device ... 15 
6.1 Arrangement ... 15 
6.2 Current Capacity ... 15 
6.3 Devices Licensing ... 15 
6.4 Impedance ... 15 
Bibliography ... 16 
Foreword
GB/T 24612 "Requirements for Electrical Safety in the Workplace" is divided into two
parts.
— Part 1. General;
— Part 2. Safety Measure of Operation on Power off.
This part is the second part of GB/T 24612.
This Part shall be under the jurisdiction of the National Technical Committee on
Electric Safety of Standardization Administration of China (SAC/TC 25).
Chief drafting organizations of this part. Mechanical Industry-Beijing Institute of
Economics of Electrotechology, Guangdong Product Quality Supervision and
Inspection Center and Schneider Electrical (China) Investment Co., Ltd.
Chief drafting staffs of this part. Ma Guifen, Zeng Yanhong, Xiang Yali and He Caifu.
This part is issued for the first time.
Requirements for Electrical Safety in the Workplace -
Part 2. Safety Measure of Operation on Power off
1 Scope
This part of GB/T 24612 specified the safety measures of operation of electrical
equipment on power off in the workplace.
Note. These electrical equipment mostly refer to the electrical switchgear and controlgear, such as low-voltage
switchgear and controlgear assemblies applicable to series of GB 7251.
This part is applicable to electrical equipment which is within life cycles such as
operation and maintenance after being manufactured in accordance with the electrical
safety requirements.
Note. This part, from the angle of the manufacturer, is used to instruct the preparation of the data provided for the
users.
2 Normative References
The following standards contain the provisions which, through reference in this Part of
GB/T 24612, constitute the provisions of this Part. For dated reference, the
subsequent modification or revisions of these publications do not apply. However, all
parties who enter into an agreement according to this Part are encouraged to study
whether the latest edition of these documents is applicable. For undated references,
the latest edition of the normative document is applicable to this Part.
GB 7251 Low-voltage Switchgear and Controlgear Assemblies (IEC 60439, IDT)
3 Terms and Definitions
3.1
Lockout
Also called lockup, a safety measure to lock a disconnecting means with power or
energy disconnected in case of other persons connecting the power or energy (like
opening the valve).
3.2
Tagout
Also called tagging, a safety measure to hang the corresponding caution or warning
board (like "No switch-on and someone is at work") on a disconnecting means with
power or energy disconnected to warn the other persons not to connect the power or
energy.
3.3
Electrical diagram
A graphic form to express the information, mainly through the graphical symbols to
express electrical items and the relation among them.
3.4
Disconnecting means
An equipment or a group of equipment capable of disconnecting the circuit of the
power supply connecting the equipment(s).
4 Procedure of Safe power-off Operation
The following procedures shall be complied with to ensure the safety of the electrical
operation when working is carried out according to Chapter 5 of this part.
a) Check the electrical diagram, chart and identification tagout of the latest
effective edition and determine all the power supply of the specific electrical
equipment.
b) Stop electro-load as required procedure and then disconnect corresponding
power switchgear.
c) If possible, conduct a visual inspection to see whether all the switches which
shall be disconnected in the power switchgear are opened completely and the
withdrawable circuit breaker is in a withdrawn position completely.
d) For electrical equipment possibly having induction voltage or storage electric
energy, after power-off operation and before contacting the conductor or circuit
parts connecting with each phase wire, discharge all the possible charged
conductors or circuit parts according to the required procedure in case of
electric shock.
e) Use the voltage detector with a large enough testing measuring range to verify
improvement and perfection of the procedure.
5.3.2 Control mode
Three control modes for the power hazard are permitted. lockout and tagout
controlled independently by the professional personnel, simple electrical lockout and
tagout and complex electrical lockout and tagout (see 5.4). The first and second
lockout and tagout operation shall be in the charge of the professional personnel. The
third lockout and tagout operation shall be in the charge of the designated persons.
5.3.3 Checking procedure
The electrical lockout and tagout shall be checked periodically by the professional
personnel in terms of at least one lockout and tagout operation in progress and the
detail content of the control procedure. The checking procedure is aimed to rectify the
control procedure or the understanding defects or mistakes of the personnel.
5.4 Control of Electric Shock Prevention
5.4.1 Control mode of professional personnel working independently
This control mode is permitted when the equipment, disconnected, with exposed
conductor or circuit parts available is subject to little daily maintenance, repairing,
adjustment, cleaning, checking, debugging and similar works. If the exposed
conductor or circuit parts is ensured to be close the disconnected switch, namely in a
position where the professional personnel who are conducting the work may see the
state of the disconnecting switch clearly and ensured to be safe, the lockout and
tagout may not be carried out for the execution of this control mode.
5.4.2 Operating mode of simple lockout and tagout
The modes other than the control mode of professional personnel working
independently (see 5.4.1) and complex lockout and tagout mode (see 5.4.3) are
regarded to be the operating mode of simple lockout and tagout. It is regarded to be a
simple lockout and tagout when the professional personnel work on or nearby the
equipment of a group of conductor or circuit parts; for this type of lockout and tagout,
the control plan of lockout and tagout procedure is not required to be prepared every
time. For every personnel conducting the simple lockout and tagout operation, they
shall dismantle the locks and tagout installed by themselves.
5.4.3 Operating mode of complex lockout and tagout
5.4.3.1 The control plan of complex lockout and tagout procedure shall be prepared
when one or more conditions below are available.
a) Multiple powers;
b) Multiple departments involved;
c) Operated by multiple procedures;
d) In different positions;
e) Multiple organizations involved;
f) Having different disconnect modes;
g) Having special order.
5.4.3.2 Operation of complex lockout and tagout shall be in the charge of a special
personnel.
A professional personnel must be designated to be responsible to control the
operation procedure of complex lockout and tagout and ensure all the powers to be
under the control of the lockout and tagout; the responsible person shall explain
clearly to all the working personnel engaging in the above works.
5.4.3.3 The duties of the responsible person for the operation procedure of complex
lockout and tagout
The responsible person is permitted to instruct other working personnel to install the
lock and tagout or replace other working personnel to install the lock and tagout. The
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(Above excerpt was released on 2016-03-27, modified on 2021-06-07, translated/reviewed by: Wayne Zheng et al.)
Source: https://www.chinesestandard.net/PDF.aspx/GBT24612.2-2009