Installation Requirements for Electrical Receptors up to 440V
1. Introduction
This document outlines the general installation requirements for electrical receptors operating at voltages up to 440V RMS between phases (254V RMS between phase and earth), supplied from a foreign network. These requirements are in accordance with Article 6 of the Low Voltage Electrotechnical Regulations and do not supersede the Low Voltage Directive (73/23/EEC) and the Electromagnetic Compatibility Directive (89/336/EEC). This applies even to receptors not supplied fully assembled, such as lighting or industrial machine equipment.
2. General Considerations
2.1. Installation Terms
Receptors must be installed according to their intended use (local class, location, etc.), considering potential mechanical stress and ambient conditions. Operating temperatures should not pose hazards to the facility or nearby objects. They must also withstand external factors like dust, moisture, gases, and vapors.
Circuits within receptors, unless otherwise specified, must be protected against overcurrent as per Section ITC-BT-22. Current-time characteristics of protective devices should be chosen based on the receptor’s characteristics and usage.
2.2. Classification of Receptors
Receptors are classified for protection against electric shock as follows:
- Class I: Basic insulation and connection to protective earth.
- Class II: Double or reinforced insulation, no earth connection.
- Class III: Safety extra-low voltage (SELV).
This classification doesn’t imply that receptors can be of any type. Safety requirements under the Low Voltage Directive may restrict the use of certain receptor types. Equipment designed for SELV (as per ITC-BT-36) but incorporating circuits operating at higher voltages are not considered Class III unless their construction ensures equivalent isolation to a safety transformer (UNE-EN 60742 or UNE-EN 61558-2-4).
2.3. Terms of Service
Receptor usage depends on its class and the installation environment. Refer to ITC-BT-24 for specific provisions. Class II and Class III receptors can be used without additional protection against indirect contact.
2.4. Voltages
Receptors should generally be connected to facilities with their rated voltage. They may have a single rated voltage or a range. Single-voltage receptors can operate within voltage variations allowed by regulations governing electricity transport, distribution, marketing, and supply. Receptors may be designed for voltage changes, and if done through switching devices, these should prevent accidental modification.
2.5. Networking Receivers
Each receptor should be powered by a dedicated device, either incorporated or in the feeder facility. Use devices listed in ITC-BT-19. Operation can affect a set of receptors unless specific requirements state otherwise. Receptors can connect directly to pipelines or via a suitable mobile cable, possibly with a plug outlet.
For direct connection to a fixed channel, ensure accessibility for operation, maintenance, and monitoring. Removable cables should have the necessary conductors, including a protective conductor if needed. Wires entering the device must be protected against traction, torsion, shear, abrasion, and excessive bending using suitable insulating devices. Do not tie or fasten ropes to the receptor.
Protective conductor length should ensure that if traction deterrents fail, they are stressed only after power conductors. For heat-producing receptors, if touchable parts reach over 85°C, cable insulation and sheathing should not be thermoplastic.
Mobile cable connection should use: plug and outlet, junction boxes, or trolleys for electrically powered vehicles. Household and similar devices should use: flexible cable with protective cover permanently attached or attached via a connector to prevent access to live parts under stress.
Cable rated voltage should be at least the supply voltage and not less than 300/300V. Minimum cross-section is 0.5mm2. Cable characteristics must suit the intended use. Pins for connecting to outlets should be types C2b, C4, C6, or ESB 25-5b (UNE 20315) or plugs according to UNE EN 50075. Non-household receptors can use BS EN 60309 series pins.
2.6. Unbalanced Phases or Large Input Fluctuations
Receptors causing significant imbalances in polyphase distributions require permission from the energy supplier. For motors driving high-torque machines and other receptors like furnaces and welding equipment that can cause large power fluctuations, ensure these don’t exceed 200% of the allocated power.
If receptors don’t meet this condition or cause disturbances in the distribution network, the supplier may deny supply and require corrective systems.
2.7. Power Factor Compensation
Facilities supplying receptors with a power factor less than 1 can be compensated, but the network’s absorbed energy cannot be capacitive. Compensation can be done:
- Individually: For each receptor or group operating simultaneously and connected via a single switch. The switch must cut off power to both the receptor(s) and the capacitor.
- For the entire facility: The compensation system must automatically ensure power factor variation stays within ±10% of the average value over an extended period.
If capacitors can be disconnected via switches, they must have ballast resistors or discharge to earth. Capacitors for improving induction motor power factor should disconnect simultaneously with the motor’s power supply. Capacitor characteristics and installation must comply with UNE-EN 60831-1 and BS EN 60831-2.