Protective extra-low voltage is a particularly safe type of power supply in which the electrical voltage is kept so low that there are no dangerous consequences for people or animals, even in the event of direct contact with live parts. This principle is used in electrical engineering primarily where there is an increased risk due to moisture, contact or confined spaces – for example in bathrooms, outdoor areas or in lighting technology.
This is a maximum voltage of 50 units for AC voltage or 120 for DC voltage. These limit values are regulated in the VDE 0100 standard and are considered safe for the human body under normal ambient conditions. The VDE standards define precise requirements for the design, application and monitoring of such systems.
A key feature of this low-voltage solution is that it must be galvanically isolated from the mains voltage – in other words, there must be no direct connection between the low-voltage network (e.g. 230 volts) and the extra-low voltage range. This separation is achieved using special transformers or electronic switching power supplies.
So-called transformers are used to generate a safe voltage level from the regular mains voltage. These electrical devices convert the input voltage to a significantly lower value. In many applications, for example in building services or commercial installations, a transformer is used specifically for this application.
It plays a particularly important role in lighting. Ceiling lights, LED systems and other light sources that are operated with low voltage usually require a ballast or transformer to provide the necessary supply. Modern LED lights often work with 12 units, making them not only energy-efficient but also particularly safe.
A well-known field of application for this technology is lighting with LED luminaires in damp rooms such as bathrooms or outdoors. As water, steam or conductive surfaces are often to be expected here, the low voltage value significantly reduces the risk of electric shock. Ceiling lights, light strips or other light sources with this safe voltage are also used in living areas to ensure a reliable environment – for example in children’s rooms or above mirrors.
In some cases, extra-low voltage (ELV) is also used if particularly sensitive areas are to be protected – for example in medical applications or toys. This extra protection is also ensured by suitable transformers.
This type of voltage offers a number of advantages. The most important aspect is undoubtedly the protection of people from dangerous electrical voltages. Even if a technical defect or cable breakage occurs, the risk of electric shock remains low – especially if the system has been installed in accordance with VDE standards.
Another advantage is the increased flexibility in installation. As no complex insulation measures are required as with mains voltage, such systems can be installed more easily and quickly – especially in furniture lighting or with indirect light sources.
However, it should not be forgotten that certain safety rules must also be observed here. Incorrectly dimensioned transformers, improper wiring or the use of non-approved components can still pose risks. This is another reason why it is important to adhere to recognized VDE standards.
In addition to lighting, extra-low voltage applications can also be found in:
Especially in combination with LED technology, this solution offers enormous potential for saving energy – while maintaining a high safety standard.
This form of electrical supply is a proven and effective principle for making energy safe and efficient to use. Whether in lighting, in devices with low energy requirements or in safety-critical applications – the combination of transformer, protection conceptand VDE-compliant installation ensures maximum safety. Thanks to modern light sources such as LEDs and compact transformers, this technology will remain an important component of intelligent electrical systems in the future.
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