Is it a dangerous job to be an electrician?

Baunetz_Knowledge

Protection against direct contact is the basic protection (1st protection level)
It provides immediate protection against dangers that result from direct contact with active, live parts. One distinguishes between:

  • complete protection by insulation (this is the most common protection), covering, cladding, large spacing
  • partial protection against accidental contact, e.g. through obstacles and (small) distance, which is only permitted within closed electrical engineering facilities

Protection against indirect contact is the fault protection (2nd protection level)
These measures protect against dangers that arise in the event of a fault from contact with touchable electrical parts of electrical equipment, the so-called body (e.g. the metal housing of an electrical device) or external conductive parts (e.g. heating, water pipes etc.). The task is to look for errors

  • switch off dangerous contact voltages or
  • to prevent dangerous contact voltages

Shutdown (or report) through protective measures with a protective conductor
Depending on the type of network (TN system, TT system, IT system), the neutral conductor N and the protective conductor PE or PEN are arranged and laid differently. Provided that there is proper earthing and equipotential bonding, it is switched off in the event of a fault with the aid of fuses or FI protective devices. Insulation monitoring devices in the IT system (does not occur in residential construction) report errors without switching off, in order not to impair ongoing production, for example. For the TN system, for example, all bodies must be connected to the neutral point of the feeding network by a protective conductor or PEN conductor (formerly neutral conductor) (previously known as "zeroing"). In the event of a short-circuit to body, a short circuit occurs and the high residual current leads to the immediate shutdown of the affected circuit by fuses or miniature circuit breakers.

Prevent dangerous contact voltages with the help of the measures:

  • Protective insulation (devices of protection class II)
  • Safety extra-low voltage (protection class III)
  • Functional extra-low voltage (e.g. for doorbell and door intercom systems
  • Protective separation (e.g. shaver socket with isolating transformer)

Protection against direct contact is an additional protection (3rd protection level)
Supplement the aforementioned protective measures if, for example, the basic protection fails and / or the error protection, i.e. protective measures in the event of indirect contact, becomes ineffective. However, it is not permitted as sole protection. This protection is achieved by the highly sensitive residual current devices (FI protection). If fault currents of 30 mA or greater occur, below which they are generally harmless to humans, RCCBs switch off within 0.2 s (some even after 20 ms). This additional protection is mandatory for new installations in some areas with special hazards, e.g. in bathrooms and shower rooms.

Expertise on the subject

Basic installations

Grounding

So-called protective earthing, ...

protection

Residual current protective devices (RCDs or FI protection)

Residual current protective devices, known under the term "FI protection", are manufactured according to the internationally harmonized standards with ...

Planning basics

Network systems

What are the basic network types and what do the grounding conditions have to do with them? An overview of TN, TT and IT systems.

Basic installations

Equipotential bonding

Equipotential bonding means all measures to eliminate electrical potential differences (voltages) between the ...

protection

Protection classes

The electrical equipment is covered by three protection classes (protection class I to III, protection class 0 is not ...