Low-voltage electrical installations –. Part 1: Fundamental principles, assessment of general characteristics, definitions. Reference number. IEC (E). National Electrical Code,® and the wiring rules promulgated by IEC , Electrical contribution has been to further the understanding of IEC ”. An international Standard such as the IEC series “Low voltage. Electrical Installations” specifies extensively the rules to comply with to ensure safety and.
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Low-voltage electrical installations –. Part 6: Verification. Reference number. IEC (E). INTERNATIONAL. STANDARD. IEC. First edition. IEC Standards for electrical installation. The IEC publishes international standards, technical guides and reports .. IEC Tel: /2 Fax to (Email: [email protected]). REGISTRATION FORM. ONE DAY SEMINAR ON IEC STANDARD.
Introduction In the preceding article we studied the basics of Earthing and also the basic most Earthing type where the neutral is grounded at source and optionally grounding is done even at customer side. Let us examine them here in detail.
IEC Standard for Earthing. It also defines three families of Earthing arrangements. The Second Letter indicates how the Earthing is done on Device side place where electricity is consumed at customer premises. N — It means that there is direct connection to neutral at the source of installation which is in turn connected to the ground.
Based on a combination of these three letters, there are three families of Earthing arrangements proposed by IEC as below: In TN type of earthing system, one of the points of the source side Generator or Transformer is connected to earth. This point is usually the star point in a three phase system.
The body of the connected electrical device is connected to earth via this earth point on the source side. See fig. N —Also called Neutral. They are connected together only at the power source. In above diagram: It is the conductor that connects Star point in a 3 phase system to the earth.
There are three sub-types of TN networks as below: In this. In this type of earthing. This type of earthing is preferred in telecommunication applications.
CH Geneva Switzerland Telephone: International Electrotechnical Commission. This is a preview Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
Technical Specifications. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate. IEC publishes International Standards. Their preparation is entrusted to technical committees. IEC shall not be held responsible for identifying any or all such patent rights. Electrical installations and protection against electric shock. This fifth edition of IEC cancels and replaces the fourth edition published in and constitutes a technical revision.
Technical Reports. IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user. IEC collaborates closely with the International Organization for Standardization ISO in accordance with conditions determined by agreement between the two organizations. To this end and in addition to other activities. Use of the referenced publications is indispensable for the correct application of this publication.
The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. Void Part 3: Void Part 4: Protection for safety Part 5: Selection and erection of electrical equipment Part 6: Verification Part 7: Requirements for special installations or locations The committee has decided that the contents of this amendment and the base publication will remain unchanged until the maintenance result date indicated on the IEC web site under "http: Part 2.
Annex B of IEC deals with protective conductor currents. The text of this standard is based on the following documents: Part 1: Fundamental principles. IEC consists of the following parts.
At this date. Protection for safety — Protection against thermal effects IEC Electrical apparatus for explosive gas atmospheres IEC Basic and safety principles for man-machine interface. Selection and erection of electrical equipment — Wiring systems IEC Man-machine interface MMI — Actuating principles. Test Ka: Salt mist IEC Environmental testing — Part 2: For dated references. Protection for safety — Protection against voltage disturbances and electromagnetic disturbances IEC Electrical installations of buildings — Part 1: Fundamental principles IEC Annex D illustrates two typical circuits of U.
In this report. Only one location for the referenced documents is indicated. These circuits were analyzed for compliance with IEC provisions.. IEC documents available as of May 1. In the U. Annex E contains an analysis of the allowable ampacities of the two documents. Annex B-2 contains identification of U. The NEC can be characterized as containing performance criteria and acceptable solutions. National Electrical Code is over years old. The Code rules take into consideration known performance capabilities and required construction features of electrical construction materials and utilization equipment.
It has been translated in Japanese. The Code consists of an introduction and nine chapters. Chapters 5. Introduction is article Chapter 8 covers communications systems and is independent of the other chapters.
This ensures that proper overcurrent protection and other safety features are provided on the equipment. It is written in mandatory language and it is suitable for use by designers.
The Code also covers installations in hazardous locations explosive atmospheres. In the converse. Whenever the NEC is revised. It is a cohesive and comprehensive document that is revised on a three-year cycle.
The Code was established at the beginning of the growth of distribution systems for electrical energy and its use for lighting and driving machinery. Text is in sections. Chapter 9 contains tables. The NEC covers electrical installations from the service point to the outlets and it includes some requirements for utilization equipment. The prescriptive requirements contain acceptable solutions.
The provisions of the NEC cover specific requirements for installation. Chapters 1 through 4 of the Code apply generally. The rules also address certain features of utilization current-using equipment. Chapters 1 through 8 contain articles. The equipment must be suitable for the circuit to which it is connected. Chapters 1 through 4 apply. It is a model code intended for legal adoption or reference by countries. The NEC is adopted and used in various jurisdictions of the United States and in a number of other countries.
These latter chapters supplement or modify the general rules. Time and resources would be required if documents were to be used to develop a national electrical installation code suitable for uniform application.
These basic principles cover hazards known by trained persons to be associated with the use of electricity. Because the European countries are in close proximity to each other. Part 3 deals with assessment of general characteristics. Other parts of IEC deal with conditions which may introduce hazards and measures of protection to be provided.
This lack of rules for higher voltages could be a serious consideration for high-rise building installations. IEC limits its scope to installations of circuits up to V. Some of the documents have not been revised since they were issued. These principles then could serve as the basis on which national wiring practices could be developed. The IEC documents cover electrical installations from the service entrance. The contents of Chapter 13 may be used as a basis for such legislation.
The effort was refocused on this objective and development of IEC documents ensued. Part 1 contains the scope. Development of electrical installation requirements in several European countries started about the same time as the National Electrical Code. Agreement on a complete set of wiring rules could not be achieved.
This document is intended to serve as a basis for development of national requirements. The multitude of differences rendered this effort unsuccessful. The fundamental principles contained in Chapter 13 of Part 1 encompass protection for safety: Part 4 addresses protection for safety. IEC is broadly performance-based and is not intended to be used directly by designers.
The note to Chapter A number of provisions in the documents are incomplete. Installations in hazardous locations explosive atmospheres are covered in separate IEC documents. Some provisions are advisory or contain recommendations. In Part 2 contains definitions.
Knowledge of the involved hazards and statements for the need of protection against such hazards may not be sufficient for guarding persons and property without more specific rules on how the protection is to be accomplished. The numbering system and updated plan are contained in Annex A-2 of this report. Part 5 deals with selection and erection of electrical equipment. Among the effects against which protection needs to be provided are overcurrent overload. This chapter includes general statements on the nature of protective devices.
Together with the permitted variations in supply system grounding earthing rules. Part 4. In areas where the general purpose utilization circuits operate at V. Rules which cover one safety feature are located in different parts of the documents. Since the IEC rules stop at the socket outlet. In a similar manner. In North America and a number of other countries. Chapter 46 covers Isolation and Switching. Example—The difficulty in using the IEC documents for direct application to an installation can be best illustrated by example.
One important consideration in development of new national electrical installation requirements. It contains common rules. The statements covering overcurrent protection. Certain aspects of overcurrent protection are treated in a number of separate sections. In the event the existing branch circuit conductors have metric dimensions and the common conductor sizes and overcurrent device ratings of the IEC standards are employed.
The higher voltage makes it easier to disconnect earth faults in TN systems without use of residual current devices RCDs. Existing Infrastructures A significant difference in electrical system characteristics that has influenced electrical safety rules is the difference in voltage for the majority of utilization circuits. In European countries and some other parts of the world.
The chapter was issued in For instance. Part 6 covers verification. Protection Against Overcurrent. Lack of code rules on safety features for electrical equipment could result in inappropriate or hazardous installations. Protection requirements are expressed in formulas and deal mainly with protection of conductors. Section on Design has Clause IEC documents include requirements for 30 milliamp triplevel RCDs only in relation to shock hazard. This is not to say that the NEC is lacking in rules for shock hazard protection.
The IEC documents contain the requirements for the additional safety features. RCDs with other ratings may be used to achieve the disconnecting times during earth-fault conditions.
The present sets of rules in both publications adequately address the hazards associated with the use of electricity for both types of building construction. This is evident from the rules for overcurrent protection. Even though IEC rules emphasize shock hazard protection. The residual current devices were initially developed to mitigate fire hazards due to ground fault currents.
Rules on grounding and bonding. In areas of the world where TT premises wiring systems exist. In the past. On the other hand. Countries with IT.
Many installation rules in the NEC address protection against fire. In Britain. The guide indicates that installations made in accordance with its guidelines will meet BS BS must be utilized.
Countries that have based their wiring rules on IEC probably had to go through a similar process and produce an installation guide or practice for use by designers. The Code is a set of requirements. It is suitable for adoption and implementation without or with modification or additional rules.
It is kept current with the state of technology on a regular three-year cycle. HD The method of implementation of IEC documents can be illustrated by the process taking place in the UK. Because of its mandatory language. They may contain references to other documents. It is written in mandatory language and does not contain any recommendations. In addition. There is an IEC based European document.
Due to its composition. It has been characterized as not being suitable for direct adoption as an installation practice. For installations other than those indicated above. The On-Site Guide is the document that is actually used by installers and verifiers for domestic installations and associated buildings.
The IEC standard on Electrical Installations of Buildings is intended to serve as a model for development of national requirements. IEC documents contain numerous normative references. This and the methods for confirming compliance with the referenced standards need to be considered when a baseline document is chosen for development of national wiring rules.
With normative references. There must be a close relationship between the provisions in product standards and the Code rules to provide an effective safety system. Where the NEC is used. The Code rules must take into consideration known performance capabilities and required construction features of electrical construction materials and utilization equipment. Where a national document would be based on IEC provisions.
There are some explanatory notes which refer to documents for a method of ascertaining certain characteristics or performance capabilities. Both the IEC and the National Electrical Code are intended to serve as a basis for national or local requirements. Not mandatory. No normative or mandatory references are in the NEC. Clause 3. Each part except Part 7 is divided into chapters. Informative references: Intended for information only. Notes associated with text are not to contain provisions necessary to claim compliance with the document.
A number of notes contain recommendations. NFPA 70 Divided into Introduction and nine chapters. Explanatory notes that may contain references to other documents. This is an unofficial publication intended only to assist users of the NEC in proper 9.
Text is in clauses or sub-clauses. Introduction is Article Type 1 Technical Report: Referenced Documents Normative references: This publication contains the text of the NEC with interspersed informational explanations. See Sec. Chapters may be divided into sections. Note 1 to Significant technical differences between the two codes are highlighted under Comparison of Significant Provisions. Annex A: Divided into seven parts.
Final acceptance is by the responsible technical committee. The explanatory material is developed by editors and voluntary sources.
Type 2 Technical Report: Publication of work still under technical development. Amendments Amendments are issued on a continual basis. Tentative interim amendments are adopted only on basis of emergency to correct gross error. By one of 20 code-making panels which have balanced interest representation such as manufacturers.
Applies also to documents in normative references. Interest representation manufacturer. One country. New editions are issued every three years.
Only the text of the NEC contained in the handbook has been subjected to the consensus process. Type 3 Technical Report: Informative publication containing collected data of a different kind from that which is normally published as an international standard. Any organization or individual from the U.
All actions are reviewed by Technical Correlating Committee. Proposals for Amendments National committees and member bodies submit proposals for amendments to the appropriate technical committee. NFPA 70 interpretations. Spanish language edition — same as above.
Chapter Single copy Edition: Where countries not yet having national regulations for electrical installations deem it necessary to establish legal requirements for this purpose. Inside back cover of NEC book: English and Spanish in separate books. Languages English and French in each document. Adoption by Reference: Public authorities and others are urged to reference this document in laws.
Cost IEC documents only no normative references. National standards based on IEC cost considerably less. Adoption by Authorities IEC For hazardous locations explosive atmospheres.
Fundamental Principles. Standards Council. Includes hazardous locations explosive atmospheres installation requirements. Standards Council in writing of such use.. Adoption by Transcription: Public authorities with lawmaking or rulemaking powers only. Any deletions. Some states. Includes rules for hazardous classified locations [explosive atmospheres]. Verification is to be by visual inspection.
Includes provisions from the service point of a premises to branch circuit outlets. No other method for verification of conformance is indicated. Layout of Subject Matter Fundamental requirements for safety Part 1. Layout of subject matter is equipment or installation method oriented.
The conductors and equipment required or permitted by the Code shall be acceptable only if approved Includes rules for appliances and other utilization equipment. Does not include rules for installations in explosive atmospheres. By authorities and verification methods under the rules or regulations existing in countries. NFPA 70 the above methods. Some entities in the U.
Does not include rules for appliances or other currentusing equipment. Coverage of Electrical System Includes provisions from the point of supply for a building to the socket outlets. Verification of Compliance By authorities and verification methods under the rules or regulations existing in countries.
Suitability of equipment may be evidenced by listing or labeling by a qualified electrical testing organization. Requirements from all the foregoing need to be brought together to assess a particular installation see Annex A-2 of this Report for the numbering system and plan of IEC Rules in Art.
Annex A indicates utilization categories where AC2 signifies starting and switching off slip-ring motors. In fact. Confusion may result. Also contains design guidance. No design guidance. Suitable for adoption.
Table contains type designations which indicate the environmental conditions against which a degree of protection is provided by motor controller enclosures. In conjunction with Sec. A similar table appears in product certification information for other electrical equipment. Fine Print Notes contain only explanations. Coded External Influences Parts 3 and 5 contain extensive lists of coded external influences and severity levels.
Published certification information and product markings indicate environments. In Sec. Need for compliance with some provisions can be agreed upon by the installer and the owner or specifier.
Most sections of the NEC were analyzed and corresponding or related requirements or definitions in IEC are indicated.
NEC T O IEC The text under each of the following headings identifies the location of the requirements with a brief statement on the subject matter.
There is no index to the IEC documents. NFPA 70 Art. Not covered Aside from Chapter 6 on Verification. Where a specific feature was not covered in IEC These are covered in Sec. From Clause If functioning is intended to include other than safety functions.
Part 1. Compliance therewith and proper maintenance will result in an installation that is essentially free from hazard but not necessarily efficient.
Also see Annex A-2 of this report. The text in italics contains a commentary on the more significant differences. IEC does not address enforcement issues.
International Electrotechnical Vocabulary. This analysis includes the definitions for which a corollary can be made to an IEC definition and those needed for clearer understanding of the U. The definitions are preceded by the IEC Part designation in parentheses.
Not covered Formal interpretation procedures are not in place. Referenced text is reproduced in Annex C of this report. The current in amperes that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Clause 6. Part 6 Verification Compliance with the safety requirements of the relevant equipment standards is to be made by visual inspection on permanently wired electrical equipment.
The following definitions are from IEC Acceptable to the authority having jurisdiction. Purely informative in nature. Brackets contain the title of the Part for other than Part Contains informative notes only for some terms in IEC The maximum current which can be carried continuously by a conductor under specified conditions without its steady state temperature exceeding a specified value. Safety System. A function intended to cut off for reasons of safety the supply from all or a discrete section of the installation by separating the installation or section from every source of electrical energy.
All circuit conductors between the service equipment or the source of a separately derived system and the final branch-circuit overcurrent device. A circuit supplying a distribution board. Contact of persons or livestock with live parts.
A part providing protection of equipment against certain external influences and. The case or housing of apparatus. Exposed as applied to live parts: Capable of being inadvertently touched or approached nearer than a safe distance by a person.
It is applied to parts not suitably guarded. A general term including material. A circuit connected Branch Circuit: The circuit conductors between the final overcurrent device protecting the circuit and the directly to current-using equipment or to socket outlets. Grounding Conductor. Disconnecting Means: A device.
Intentionally connected to earth through a ground connection or connections of sufficiently low impedance and having sufficient current-carrying capacity to prevent the buildup of voltages that may result in undue hazards to connected equipment or to persons. Any item used for such purposes as generation.
National Electrical Code, NFPA 70 The conductor used to connect the noncurrentcarrying metal parts of equipment, raceways, and other enclosures to the system grounded conductor, the grounding electrode conductor, or both, at the service equipment or at the source of a separately derived system.
IEC conductor required by some measures for protection against electric shock for electrically connecting any of the following parts: A protective conductor connecting the main earthing terminal or bar to the earth electrode. Grounding Electrode Conductor: The conductor used to connect the grounding electrode to the equipment grounding conductor, to the grounded conductor, or to both, of the circuit at the service equipment or at the source of a separately derived system.
Covered, shielded, fenced, enclosed, or otherwise protected by means of suitable covers, casings, barriers, rails, screens, mats, or platforms to remove the likelihood of approach or contact by persons or objects to a point of danger. A part providing protection against direct contact from any usual direction of access and Obstacle: A part preventing unintentional direct contact, but not preventing direct contact by deliberate action. Identified as applied to equipment: Recognizable as suitable for the specific purpose, function, use, environment, application, etc.
Suitability of equipment for a specific purpose, environment, or application may be determined by a qualified testing laboratory, inspection agency, or other organization concerned with product evaluation. Such identification may include labeling or listing. See definitions of Labeled and Listed. Interrupting Rating: The highest current at rated voltage that a device is intended to interrupt under standard test conditions. A breaking capacity for which the prescribed conditions include a short circuit at the terminals of the switching device.
Isolated as applied to location: Not readily accessible to persons unless special means for access are used. National Electrical Code, NFPA 70 an organization that is acceptable to the authority having jurisdiction and concerned with product evaluation, that maintains periodic inspection of production of labeled equipment or materials, and by whose labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner.
Equipment, materials, or services included in a list published by an organization that is acceptable to the authority having jurisdiction and concerned with evaluation or products or services, that maintains periodic inspection of production of listed equipment or materials or periodic evaluation of services, and whose listing states that either the equipment, material, or services meets identified standards or has been tested and found suitable for a specified purpose.
The means for identifying listed equipment may vary for each organization concerned with product evaluation, some of which do not recognize equipment as listed unless it is also labeled. Use of the system employed by the listing organization allows the authority having jurisdiction to identify a listed product. Live Parts: Electric conductors, buses, terminals, or components that are uninsulated or exposed and a shock hazard exists.
A conductor or conductive part intended to be energized in normal use, including a neutral conductor, but, by convention, not a PEN conductor. This term does not necessarily imply a risk of electric shock. Any current in excess of the rated Overcurrent: Any current exceeding the rated current of equipment or the ampacity of a conductor. For conductors, the rated value is the currentIt may result from overload, short circuit, or ground carrying capacity.
A current in excess of rating may be accommodated by certain equipment and conductors for a given set of conditions.
Therefore the rules for overcurrent protection are specific for particular situations. Operation of equipment in excess of normal, full-load rating, or of a conductor in excess