Zeroing

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The zeroing ( earthing ) is a protective measure against personal injury in the event of indirect contact with electrical conductors. Zeroing or earthing is generally carried out by connecting the electrically conductive and accessible housings of equipment ("bodies") with a protective conductor .

The term zeroing has largely been eliminated from the German VDE standards and the Swiss NIN and replaced by the terms protective grounding and protective equipotential bonding. Only in the Austrian ÖVE / ÖNORM E 8001-1: 2010 and in the Austrian Electrical Engineering Act ( ETG ) 1992 is the term still used in the usual way.

Types of zeroing

Which one is different zeroing without special protective conductor , often called Classical zeroing refer to operations of the PEN conductor both as neutral and as a protective conductor is used ( TN-C network ) and zeroing with special protective conductor , sometimes referred to as electroless or modern zeroing referred with separate PE and N conductors ( TN-S network ).

Zeroing without a special protective conductor

Zeroing without a special protective conductor

Zeroing without a special protective conductor, in Switzerland zeroing scheme III , commonly known as classic zeroing , was introduced by the AEG around 1913. Previously (around 1885), protective earthing in systems without a neutral conductor (i.e. in networks with 3 × 220 V, in which a metal water pipe network was also available) was the oldest known protection system.

The classic zeroing involves dangers if the PEN conductor is interrupted and the outer conductor is still connected to a consumable . Then the full voltage of the outer conductor to earth is applied to touchable parts of housings, today usually 230 V. Even in normal operation, a certain low voltage to earth is applied to the housings, which according to Ohm's law by the (low) Resistance of the PEN conductor itself and the current flowing through it. In multi-phase installations, uneven loading of the outer conductors also leads to zero point shifts. This is also due to the voltage drop on the neutral conductor. This also means that currents can flow on equipotential bonding lines (connection of the PEN with earthed parts, e.g. the water installation) that could U. lead to overloading of the earth connection. In the GDR, aluminum cables were also installed that had unreliable terminal points per se.

For these reasons, “classic zeroing” has been banned for new systems in Germany since May 1, 1973, and in Switzerland since January 1, 1974. There was a transition period until March 31, 1974 for systems under construction in Germany. Zeroing connections there may only be made with conductors with a cross-section of at least 10 mm² copper or 16 mm² aluminum (for the first time with VDE 0100 / 5.73 § 10 a ) 2.1.)  

Grandfathering

The grandfathering allows systems that were built according to earlier standards (and still comply with them) to continue to be operated if no significant changes are made. However, from the transition point to the old system, extensions must always be built according to current standards.

Germany

What was built in Germany according to previously valid standards (including TGL ) only needs to be changed (adapted) through the existing protection anchored in building law if this has been specified in DIN VDE 0100 (VDE 0100 to 1976). The replacement of electrical equipment requires no adjustments to the current standards when the new equipment is exactly the same function of the old resource have (which z. B. the replacement of old rotary changeover switches, toggle switches for lighting not given). Accordingly, the "zeroing - established by connecting the system parts to be protected to the neutral conductor", today referred to as the PEN conductor (e.g. according to VDE 0100 / 12.65, § 10N, a - or in TGL 200-0602 / 03, Section 9.3), grandfathering in the new and old federal states.

Switzerland

In Switzerland there is no legal basis for an obligation to retrofit, which is why systems must comply with the rules and regulations applicable at the time of creation in accordance with Art. 3 NIV (existing protection) as long as no changes have been made to them. However, as part of periodic controls ( Art. 36 NIV), the owners are informed in writing that the facility is out of date.

Improve protection

Although older systems only have to be retrofitted in the event of significant changes or extensions due to the existing protection, it makes sense to retrofit at least for "rooms with bathtub or shower" to the current standard with a separate protective conductor and residual current circuit breaker (RCD) (DIN VDE 0100-700 : 2008-10).

Since June 1, 2007 (with a transition period up to February 1, 2009), in accordance with DIN VDE 0100-410: 2007-06, Section 411.3.3, all sockets in new systems that are used by non-electrotechnical people have been fitted with a residual current device (RCD) must be equipped with a rated differential current of a maximum of 30 mA (sockets up to 20 A indoors, up to 32 A outdoors for the entire circuit supplying the sockets).

Section 411.3.3 in DIN VDE 0100-410 (VDE 0100-410): 2018-10 has been further adapted since October 1, 2018 (with a transition period until July 7, 2020). Indoor sockets with a rated current of up to 32 A also require a residual current device (RCD) with a rated differential current of no greater than 30 mA. Sockets can be exempted from this if measures are taken (a risk assessment according to the Industrial Safety Ordinance (BetrSichV) is necessary for this), which permanently excludes general use (e.g. by the electrotechnical layperson).

Initial test and recurring test

New systems are to be checked before the initial start-up according to DIN VDE 0100-600: 2008-06 and the test results are to be documented. A DIN VDE 0100-610 that was originally also usable for recurring tests was withdrawn with a transition period until September 1, 2009. Recurring tests are handled in Germany according to DIN VDE 0105-100: 2009-10. This standard contains regular intervals for tests at production sites, but does not contain any binding test intervals for apartments and other private areas. A frequently published statement that negligence has an impact on insurance coverage is not understandable for the private sector.

Put simply, it must be ensured that the system complies with the standards that were relevant at the time of construction. See the statement in note 1 on page 19 of VDE 0105-100: “Existing systems may have been planned and built in accordance with earlier editions of the series of standards (DIN) VDE 0100 that were to be used at the time of planning and construction. This does not necessarily mean that these facilities are unsafe. "

For Austria, the Electrical Engineering Ordinance 2002, Federal Law Gazette II 223/2010, issued for the Electrical Engineering Act 1992, Federal Law Gazette No. 106/1993, stipulates that the electrical system must be checked and, if necessary, retrofitted when an apartment is re-let:

Excerpt: § 7a ETV. When renting an apartment in accordance with § 2 Paragraph 1 MRG, Federal Law Gazette No. 520/1981 igF, it must be ensured that the electrical system of the apartment complies with the provisions of ETG 1992 ... for systems that do not have additional protection in accordance with ÖVE / ÖNORM E 8001 -1: 2000-03-01, in the version of the changes ÖVE / ÖNORM E 8001-1 / A1: 2002-04-01, ÖVE / ÖNORM E 8001-1 / A2: 2003-11-01, ÖVE / ÖNORM E 8001-1 / A3: 2007-10-01 and ÖVE / ÖNORM E 8001-1 / A4: 2009-04-01, the protection of people in the electrical system by installing at least one is, regardless of the existing system status A residual current circuit breaker with a nominal residual current of not more than 30 mA must be ensured directly in front of the line protection devices in the apartment .... In any case, written documentation is sufficient, from which the fulfillment of the facts mentioned in the text can be seen (e.g. Test results of the federal guild of electrical and alarm system technicians as well as communication electronics, test report okoll according to TAEV, electrical report for Viennese living etc.).

Norms

  • VDE 0100 / 5.73 Regulations for the erection of high voltage systems with nominal voltages up to 1000 V (withdrawn 2008-09)
  • DIN VDE 0100-100: 2009-06 DIN Construction of low-voltage systems - Part 1: General principles, provisions of general characteristics, terms (IEC 60364-1: 2005, modified)
  • DIN VDE 0100-410: 2007-06 Construction of low-voltage systems - Part 4-41: Protective measures - Protection against electric shock (IEC 60364-4-41: 2005-12, modified)
  • DIN VDE 0100-600: 2008-06 Installation of low-voltage systems - Part 6: Tests (IEC 60364-6: 2006, modified)
  • DIN VDE 0105-100: 2009-10 Operation of electrical systems
  • ÖVE / ÖNORM E 8001-1: 2010-03 Installation of electrical systems with nominal voltages up to AC 1000 V and DC 1500 V Part 1: Terms and protection against electric shock (protective measures)
  • NIN 2010 ( SEV 1000) Low-voltage installation standards (Switzerland)

literature

  • Wilhelm Rudolph: VDE series 39; "Introduction to DIN VDE 0100", electrical systems in buildings . 2nd Edition. VDE Verlag GmbH, Berlin and Offenbach 1999, ISBN 3-8007-1928-2 .

See also

Individual evidence

  1. ^ Wilhelm Rudolph: VDE series 39 , introduction to DIN VDE 0100. 2009, p. 107.