Electrical Heating Installation Requirements According to European Directives
1. Purpose and Scope
This investigation aims to determine the installation requirements for electrical heating appliances that convert electrical energy into heat. These instructions comply with the applicable European directives as stated in Article 6 of the Low Voltage Regulation.
2. Domestic and Commercial Appliances
2.1. Appliances for Heating Liquids
Household appliances with bare heating elements immersed in water, where the water forms part of the electrical circuit, are prohibited.
2.2. Appliances for Space Heating
These appliances must be installed in alcoves or boxes constructed of, or lined with, non-combustible materials. Installation must follow the manufacturer’s instructions regarding minimum distances to walls, floors, and other combustible surfaces or objects. If no instructions are provided, maintain a minimum distance of 8 cm from all sides, except for appliances with light-emitting heating elements behind openings or vents. In such cases, the distance between these openings and fuel elements must be at least 50 cm.
2.3. Stoves, Ovens, and Hobs
These appliances must be connected to their power supply through omnipolar cut-off switches, sockets, or similar devices. Appliances intended solely for cooking and ovens with non-glowing elements must not be installed in enclosed spaces with explosion risks.
3. Industrial Equipment
Industrial heating appliances intended for contact with combustible or flammable materials must have a temperature limiter to interrupt or reduce heating before dangerous temperatures are reached, even under fault conditions or misuse.
3.1. Appliances for Heating Liquids
Appliances for heating flammable or combustible liquids must have a temperature limiter to prevent dangerous temperatures, even under fault conditions or misuse.
3.1.1. Water Heaters Where Water is Part of the Circuit
Boilers where water is part of the electrical circuit are prohibited in domestic installations or where they are intended for use by non-specialized personnel. The following requirements apply to these devices:
- Power supply must be AC with a frequency of 50 Hz or higher.
- A built-in and installed circuit breaker must control the power supply, meeting these conditions:
- It must be an omnipolar simultaneous cutting device.
- It must have overload protection in each conductor connected to an electrode.
- It must be easily controllable from the installation site, either directly or via remote control. In the latter case, indicator lamps must show the switch’s open or closed position.
- The metal boiler and its earth must be connected to the deck and any metal armor of the power cord.
- The grounding conductor’s cross-section must not be less than the largest supply conductor, with a minimum of 4 mm².
Depending on the device, these additional requirements apply:
- If electrodes are directly connected to a phase with more than 440 volts, an RCD must disconnect the electrodes if there’s a ground leakage current exceeding 10/100 of the boiler’s rated current under normal operation. Up to 15/100 may be allowed for stable operation.
- If electrodes are connected to 50-440V DC, the boiler must be connected to the supply neutral and ground. The neutral conductor’s capacity must not be less than the largest supply conductor.
3.1.2. Heaters with Bare Heating Elements Submerged in Water
These are allowed in industrial settings where a potential difference exceeding 24 volts may exist between accessible water or metal parts in contact with it and nearby conductors, unless they are demonstrably isolated from ground.
3.2. Cooking Appliances and Furnaces
Accessible parts of ovens that can reach dangerous temperatures must have protective covers or visible warning signs. Ovens with significant leakage current, such as resistance ovens, should be fed according to Schedule C of the TN system. Cooking appliances and ovens with non-glowing elements must not be installed in enclosed spaces with explosion risks.
3.3. Arc Welding Apparatus
Arc welding apparatus must meet the following installation and usage requirements:
- The device’s masses must be grounded. Connecting one pole of the welding circuit to these masses is permissible if stray currents don’t reach dangerous levels due to grounding. Otherwise, ground the welding circuit only at the workplace.
- Power circuit connection terminals for manual welding equipment must be well-insulated.
- Ventilation slots must be designed to prevent access to live parts.
- Each device must have an omnipolar power cut-off switch and an overload protection device regulated to a maximum of 200% of its rated power, unless the circuit conductors are protected by an overload device set to the same intensity.
- Electrode holders, handles, and jaws must be completely insulated.
- Electrode holders must have discs or screens to protect operators’ hands from the arc’s heat.
Operators must follow these safety instructions:
- Make live parts inaccessible to the electrode holder when not in use.
- Prevent contact between electrode holders and metal objects.
- Connect the welding circuit’s return conductor to nearby metal parts.
For localized welding, using low voltages is recommended. Otherwise, the open-circuit voltage between the electrode and workpiece must not exceed 90V RMS AC or 150V DC.