1 General Provisions
1.0.1 This code is prepared with a view to guaranteeing the installation quality of low-voltage apparatus, to promoting technical progress of construction and installation and to ensuring the safe operation of installed equipment.
1.0.2 This code is applicable to the installation and acceptance of universal low-voltage apparatus for AC 50Hz or 60Hz and rated voltage of 1000V or below, and for DC rated voltage of 1500V or below.
1 Installation and acceptance of the household appliances and electrotechnical instrumentation of which permanent installation is not required and of complete set of electrical devices on panel, cabinet and case;
2 Installation and acceptance of the low-voltage apparatus in specific environments.
1.0.3 The construction and acceptance of low-voltage apparatus shall comply with not only this code but also those in the current relevant standards of the nation.
2 Terms
2.0.1 Low-voltage apparatus
The electrical device in circuit at AC 50Hz or 60Hz and rated voltage of 1000V or below, and at DC rated voltage of 1500V or below, which functions for on-off, protection, control or regulation.
2.0.2 Circuit-breaker
A mechanical switching device which can connect, carry and disconnect current under normal circuit condition as well as in the abnormal circuit specified.
2.0.3 Switch
A mechanical switching device which can connect, carry and disconnect current under normal circuit condition as well as in the specified abnormal circuit within the stipulated time limit.
2.0.4 Disconnector
A mechanical switching device which meets the specified functional requirement for disconnection in disconnected mode.
2.0.5 Switch-disconnector
A switch capable of disconnecting as required by the disconnector in disconnected mode.
2.0.6 Fuse-combination unit
A composite apparatus in which a mechanical switching device is assembled with one or more fuses within the same unit.
2.0.7 Residual current device (RCD)
A mechanical switching device which can connect, carry and disconnect current under normal operating condition and can disconnect the contact once the residual current reaches the specified value under specified condition.
2.0.8 Surge protective device (SPD)
An electrical device used to restrict transient overvoltage and discharge surge current, which at least contains one nonlinear element.
2.0.9 Contactor
Non-manual-operated mechanical switching device with only one stop position, which can connect, carry and disconnect current under normal circuit condition.
2.0.10 Starter
Electric apparatus in which all the connection and disconnection modes required for starting and stopping motor as well as an appropriate overload protection are combined.
2.0.11 Soft starter
A special form of AC semiconductor motor controller of which the starting function is limited to raising of control voltage and (or) current and may include controllable acceleration; and the additional control function is limited to full voltage operation. It may also serve a function of motor protection.
2.0.12 Frequency converter
Electrical equipment used for changing the frequency of alternating current. It also has an auxiliary function of changing the voltage of alternating current.
2.0.13 Resistor
Electric apparatus that is used based on its resistance.
Electric apparatus used for restricting the current of regulator circuit or converting electricity into heat.
2.0.14 Rheostat
Electric apparatus composed of resistor parts or components (made of resistance materials) and switching devices, which can change the resistance value by stage or uniformly without disconnecting circuit.
2.0.15 Electromagnet
Magnet which needs current to generate and maintain the magnetic field.
Electric apparatus composed of coil and iron core, which, once energized, generates attraction converting electricity into mechanical energy and is so operated to drag a mechanical device or ferromagnetic object to meet the expectation.
2.0.16 Fuse
Electric apparatus of which the circuit it connected and power supply are disconnected by appropriately blowing out one or several specially-designed components as the current exceeds the specified value after an enough long period. A fuse includes all the components that constitute the complete electric apparatus.
2.0.17 Clearance
The shortest linear distance between two conductive components.
2.0.18 Residual current
The vector sum of the instantaneous value of the current flowing through the RCD primary loop.
2.0.19 Residual operating current
The residual current value which actuates RCD under specified conditions.
1 General Provisions
2 Terms
3 Basic Requirement
4 Low-Voltage Circuit-Breaker
5 Switch, Disconnector, Switch-Disconnector and Fuse-combination Unit
6 Residual Current Device and Surge Protective Device
7 Contactor, Motor Starter and Frequency Converter
8 Control Switch
9 Low-voltage Fuse
10 Resistor, Rheostat and Electromagnet
11 Test
12 Check and Acceptance of Work
Appendix A Tightening Torques of Screw-type Terminals
Appendix B Temperature-rise Limits of Terminals
Appendix C Temperature-rise Limits of Accessible Parts
Appendix D Temperature-rise Limits of Terminals and Accessible Parts for Low-voltage Circuit-breakers
Explanation of Wording in This Code
List of Quoted Standards
1 General Provisions
1.0.1 This code is prepared with a view to guaranteeing the installation quality of low-voltage apparatus, to promoting technical progress of construction and installation and to ensuring the safe operation of installed equipment.
1.0.2 This code is applicable to the installation and acceptance of universal low-voltage apparatus for AC 50Hz or 60Hz and rated voltage of 1000V or below, and for DC rated voltage of 1500V or below.
1 Installation and acceptance of the household appliances and electrotechnical instrumentation of which permanent installation is not required and of complete set of electrical devices on panel, cabinet and case;
2 Installation and acceptance of the low-voltage apparatus in specific environments.
1.0.3 The construction and acceptance of low-voltage apparatus shall comply with not only this code but also those in the current relevant standards of the nation.
2 Terms
2.0.1 Low-voltage apparatus
The electrical device in circuit at AC 50Hz or 60Hz and rated voltage of 1000V or below, and at DC rated voltage of 1500V or below, which functions for on-off, protection, control or regulation.
2.0.2 Circuit-breaker
A mechanical switching device which can connect, carry and disconnect current under normal circuit condition as well as in the abnormal circuit specified.
2.0.3 Switch
A mechanical switching device which can connect, carry and disconnect current under normal circuit condition as well as in the specified abnormal circuit within the stipulated time limit.
2.0.4 Disconnector
A mechanical switching device which meets the specified functional requirement for disconnection in disconnected mode.
2.0.5 Switch-disconnector
A switch capable of disconnecting as required by the disconnector in disconnected mode.
2.0.6 Fuse-combination unit
A composite apparatus in which a mechanical switching device is assembled with one or more fuses within the same unit.
2.0.7 Residual current device (RCD)
A mechanical switching device which can connect, carry and disconnect current under normal operating condition and can disconnect the contact once the residual current reaches the specified value under specified condition.
2.0.8 Surge protective device (SPD)
An electrical device used to restrict transient overvoltage and discharge surge current, which at least contains one nonlinear element.
2.0.9 Contactor
Non-manual-operated mechanical switching device with only one stop position, which can connect, carry and disconnect current under normal circuit condition.
2.0.10 Starter
Electric apparatus in which all the connection and disconnection modes required for starting and stopping motor as well as an appropriate overload protection are combined.
2.0.11 Soft starter
A special form of AC semiconductor motor controller of which the starting function is limited to raising of control voltage and (or) current and may include controllable acceleration; and the additional control function is limited to full voltage operation. It may also serve a function of motor protection.
2.0.12 Frequency converter
Electrical equipment used for changing the frequency of alternating current. It also has an auxiliary function of changing the voltage of alternating current.
2.0.13 Resistor
Electric apparatus that is used based on its resistance.
Electric apparatus used for restricting the current of regulator circuit or converting electricity into heat.
2.0.14 Rheostat
Electric apparatus composed of resistor parts or components (made of resistance materials) and switching devices, which can change the resistance value by stage or uniformly without disconnecting circuit.
2.0.15 Electromagnet
Magnet which needs current to generate and maintain the magnetic field.
Electric apparatus composed of coil and iron core, which, once energized, generates attraction converting electricity into mechanical energy and is so operated to drag a mechanical device or ferromagnetic object to meet the expectation.
2.0.16 Fuse
Electric apparatus of which the circuit it connected and power supply are disconnected by appropriately blowing out one or several specially-designed components as the current exceeds the specified value after an enough long period. A fuse includes all the components that constitute the complete electric apparatus.
2.0.17 Clearance
The shortest linear distance between two conductive components.
2.0.18 Residual current
The vector sum of the instantaneous value of the current flowing through the RCD primary loop.
2.0.19 Residual operating current
The residual current value which actuates RCD under specified conditions.
Contents of GB 50254-2014
1 General Provisions
2 Terms
3 Basic Requirement
4 Low-Voltage Circuit-Breaker
5 Switch, Disconnector, Switch-Disconnector and Fuse-combination Unit
6 Residual Current Device and Surge Protective Device
7 Contactor, Motor Starter and Frequency Converter
8 Control Switch
9 Low-voltage Fuse
10 Resistor, Rheostat and Electromagnet
11 Test
12 Check and Acceptance of Work
Appendix A Tightening Torques of Screw-type Terminals
Appendix B Temperature-rise Limits of Terminals
Appendix C Temperature-rise Limits of Accessible Parts
Appendix D Temperature-rise Limits of Terminals and Accessible Parts for Low-voltage Circuit-breakers
Explanation of Wording in This Code
List of Quoted Standards
