Any electrical appliance may break. If he just stopped working - it's not so bad. Worse, if the malfunction leads to electric voltage on the elements of its design, which the user considers safe. Carelessly touching such an object, a person will be shocked, injured or worse ...
What is protective grounding
With an internal break in the conductor, it becomes possible to touch the body of the electrical panel or other device, and in this case the latter will be a mortal danger, invisible, and therefore doubly terrible. To avoid such situations, grounding devices are used . They are mounted very simply, but they must certainly meet a number of requirements.
Outdoor equipment, as well as any equipment located in humid rooms, must be grounded and grounded if the supply voltage exceeds 42 V AC, or 110 V DC. The same applies to all metal non-conductive parts of the power tool, boxes, panels and structures in which the cable is held.
What grounding consists of
Grounding devices consist of two main parts.
The first of them is called a ground electrode system, and most often it is a natural building element, such as fittings, buried pipelines and other parts that provide reliable and repeated contact with the ground. If due to some circumstances such structures are absent or inaccessible, artificial grounding devices are used. They are steel corners buried in the ground to a depth of at least 60 cm with a side size of 5 cm and a thickness of at least 4 mm. The length of each of these elements should be at least 3 meters, they go deep into the ground, then steel strips are welded to them, to which the conductors are fastened, that is, the second part of the structure ensuring electrical safety.
Grounding requirements
The resistance of the grounding device should be minimal, so the requirements for contact reliability are very high. Its main purpose is to create conditions for disconnecting the power supply in case of contact of the live part with elements that should not be energized under normal conditions. Human life often depends on how quickly emergency blackouts occur.
Ground Monitoring
In order to control the degree of electrical safety, a periodic measurement of the grounding device is performed. The physical meaning of this procedure is to determine the actual resistance through which current will flow in an emergency. For this, special devices are used, equipped with control probes and representing accurate ohmmeters (for example, MRU-101).
At enterprises, specific officials are responsible for electrical safety, usually the chief power engineer, the head of the labor protection service and, of course, the management. In your own apartment, summer house or private building, grounding devices are controlled by the owners of the property.
Be careful and careful!