General Requirements of the NEC Advanced Course. Building Officials and Inspectors Educational Association

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1 General Requirements of the NEC Advanced Course Building Officials and Inspectors Educational Association

2 General Requirements -NEC Course Outcome Explain general requirements found in Article 110 of the National Electrical Code (NEC)

3 General Requirements -NEC You will have a better understanding: What is included in the NEC's general requirements The use of listed equipment How interrupting ratings and short-circuit current ratings address fault current The concept of "mechanical execution of work"

4 General Requirements -NEC You will have a better understanding: The importance of field equipment markings, including flash hazard warnings marking of available fault current identification of disconnects

5 General Requirements -NEC You will have a better understanding: labeling of switchboards and panelboards Indoor and outdoor enclosures Spaces for electrical equipment, including working spaces

6 Article 110 includes some of the broadest requirements in the National Electrical Code

7 The scope statement in Section says the article covers general requirements for the examination and approval, installation and use, access to and space about electrical conductors and equipment, enclosures intended for personnel entry and tunnel installation

8 Simply stated Article 110 covers: Approval of Equipment Installation and Use Access and spaces for equipment

9 Section 110.2: Very broad requiring that everything installed under the National Electrical Code must be acceptable to the authority having jurisdiction.

10 Section In itself specifies that conductors required or permitted by the Code are all required to be approved

11 Section 110.3(A) provides a list of eight considerations that should be used in Judging Equipment

12 The Authority Having Jurisdiction can use this list of eight criteria to determine whether or not materials or equipment should be approved.

13 Anyone who is seeking approval from the authority might also use this list to provide information to show that the issues in the list are all addressed somehow with regard to safe application and use of that particular item of equipment

14 The NEC requires that some equipment be listed, such as: Type NM Cable (Section 334.6) Flexible Metal Conduit (Section 348.6) Electrical Metallic Tubing (Section 358.6) All Luminaries (Section 410.6)

15 Some things like conduit straps or staples for cables may not be available as listed products.

16 Authorities Having Jurisdiction will require many items to be listed because they cannot properly evaluate the equipment on the field.

17 Section 110.3(B) Addresses a general requirement that all listed or labeled equipment must be installed in accordance with any instructions that are included in its listing or labeling

18 Section 110.3(B) Instructions that are included in the listing may not necessarily be found on the equipment itself.

19 Section 110.3(B) That may have to be sought from the listing agency by the Authority Having Jurisdiction or by the user.

20 Section 110.3(B) For example Underwriters Laboratory White Book contains a significant amount of information about the identification and use of various kinds of listed electrical equipment

21 Section 110.3(B) Equipment labeling on the other hand is usually readily available and may include a lot of information and instructions that must be followed

22 Section 110.3(B) Such as torque requirements and permitted sizes and types of conductors, as well as other information such as interrupting ratings and short circuit current ratings

23 Sections through address some very general issues that are applied throughout the National Electrical Code

24 Such as: Voltages that are used The requirements for voltage ratings of connected equipment Conductor sizes And Wiring methods that may be used

25 Section Describes conductors and establishes the assumption in the National Electrical Code that conductors will be copper unless specified otherwise

26 Section Describes conductor sizes as being specified in American Wire Gauge (AWG) sizes or in circular mils

27 Section Requires all wiring to be free of short circuits and ground faults, other than as permitted in the Code

28 Section States only the wiring methods that are approved and included in the Code are suitable and actually covered by the National Electric Code

29 Section is a more specific requirement than the previous sections

30 Section addresses interrupting ratings, which are the ratings of equipment intended to interrupt current at fault levels, as opposed to a switch or other device that is only intended to turn a piece of equipment on or off under normal currents

31 The definition of interrupting rating is found in Article 100: The highest current at rated voltage that a device is identified to interrupt under standard test conditions.

32 Equipment intended to interrupt current at other than fault levels may have its interrupting rating implied in other ratings, such as horsepower or locked rotor current

33 Fuses or circuit breakers that do not have adequate interrupting ratings could rupture while attempting to clear a short circuit. Interrupting ratings should not be confused with short circuit current ratings, which are further explained in Section

34 A fault current is excess current (also Called overcurrent) that goes through a circuit because something has gone wrong.

35 It can be one of three things: A short circuit occurs when two or more normal current carrying conductors make unintended contact

36 It can be one of three things: A ground fault occurs when an ungrounded conductor comes into contact with something grounded such as a conduit or the frame of some electrical equipment

37 It can be one of three things: A ground fault occurs when an ungrounded conductor comes into contact with something grounded such as a conduit or the frame of some electrical equipment

38 It can be one of three things: An overload occurs when equipment draws current over its normal rating, or conductors carry more current than their rated ampacity and the current persists for a sufficient length of time that it could cause damage or dangerous overheating

39 Faults

40 Overload

41 To prevent extensive damage from short circuits and ground faults, it is necessary to determine how much current could possibly flow in a circuit, based on the capacity of the source and the amount of impedance in the circuit up to the point of the fault

42 Based on how much current is actually available, equipment can be selected that is capable of interrupting that much fault current, such as a circuit breaker or a fuse. This type of equipment would be required if the intention is to interrupt as fault levels

43 Short circuits and ground faults typically occur because of some kind of damage to a conductor that keeps the insulation from working properly. In either case, a very high current results, because the impedance of the circuit is dramatically lowered

44 Overcurrent protective devices (such as fuses and circuit breakers) should be selected to ensure that the short circuit current rating of the system components is not exceeded should a short circuit or high level ground fault occur

45 Section Addresses the requirement for short circuit current ratings, which are essentially a measurement of the amount of current that can flow through equipment withour causing extensive damage

46 Section Short Circuit Current Rating The prospective symmetrical fault current at a nominal voltage to which an apparatus or system is able to be connected without sustaining damage exceeding defined acceptance criteria

47 Section When a short circuit occurs, a particular piece of equipment might be damaged, or parts of it might have to be repaired or replaced, but the damage would not extend significantly beyond the equipment

48 Section The short circuit current rating indicates that the equipment will allow that much current to flow without a catastrophic failure

49 Section Some types of equipment are really only intended to interrupt normal levels of current, such as some toggle switch or contactor for controlling lighting.

50 Section That type of equipment is not required to have an interrupting rating but is usually required to have a short circuit rating

51 Section Requires that the installation be done in a neat and workmanlike manner

52 Section What constitutes neat and workmanlike manner?

53 Section The informational note that follows refers to ANSI/NECA 1, Standard Practices for Good Workmanship in Electrical Contracting as an accepted industry standard

54 Section However while this is certainly a useful standard, following this is not required under the National Electrical Code and even this standard still leaves some room for judgement and opinion

55 Section (A) Requires that unused and unintended openings (such as knockouts in enclosures that may have been knocked out by accident or for a raceway or cable that was never installed) must be put back together to restore the integrity of the enclosure

56 Section (A) If the opening is intended for some purpose (perhaps drainage or mounting) then it is not required to be sealed up.

57 Section (A) The primary purpose of an enclosure is to protect electrical system from external influences, typical things like dirt and water, but also to protect from accidental contact.

58 Section (B) Addresses the integrity of electrical equipment and connections requiring that panel boards and other electrical parts be protected from the work of other trades.

59 Section (B) This section addresses contamination that would interfere with the electrical function of the equipment, but it does not address insignificant levels of contamination.

60 Section (B) For example, the bus bars of a panel board must not be painted or contaminated with various kinds of finish materials that are used during construction. It does not specify how protection is to be provided.

61 Section (B) For example, the bus bars of a panel board must not be painted or contaminated with various kinds of finish materials that are used during construction.

62 Section Requires the marking of the available fault current.

63 Section This fault current marking must: Indicate the date that the fault current calculation was performed.

64 Section This fault current marking must: Be durable enough to withstand whatever environment it is exposed to.

65 Section This fault current marking must: Be revised to indicate the new levels, as modifications are made that affect the maximum available fault current

66 Section The primary reason for this requirement is to facilitate enforcement of the requirements in Sections and to have interrupting ratings and short circuit current ratings that are adequate for the fault current that is available

67 Section This only applies to service equipment in non dwelling units. Although the requirement for interrupting ratings applies to all installations under the National Electrical Code

68 Section The markings are not intended for or adequate for determining the level of arc flash hazard.

69 Section Requires every disconnect to be legibly marked to indicate its use, that is, to indicate what it disconnects.

70 Section If there are multiple switches and multiple pieces of equipment, each switch must be identified to show what equipment it is intended to control or disconnect.

71 Section The one exception to the rule, where a disconnect does not require labeling, is when it s obvious what the switch controls, for example, if the switch is next to a single piece of equipment

72 Section

73 Section Section is similar, also requiring all switchboards and panelboards to have all their circuit devices marked to clearly indicate what circuit they control

74 Section

75 Section Simply identifying circuits as receptacles or lights are not permitted.

76 Section Disconnects must be identified specifically and in a way that distinguishes every circuit uniquely and does not use any conditions or transient occupancy

77 Section Describing the circuit as conference room lights or by a room number is acceptable. Identifying the circuit as Bob s Office is neither permitted or adequate because the person s occupancy of that particular office would be considered transient.

78 Section A general requirement that addresses enclosures for outdoor use and indoor use.

79 Section All enclosures are required to provide protection from incidental contact with the enclosed equipment

80 Section Indoor enclosures are required, at a minimum, to provide protection from falling dirt in addition to protection from whatever other environmental conditions that may be present

81 Section Outdoor enclosures are required to provide some protection from falling dirt, rain, snow and sleet, or even submersion, depending on the exposure.

82 Table Table covers enclosures for equipment rated 600 volts or less and describe what type of external environmental influence each type of enclosure is intended to withstand.

83 Table For example an indoor enclosure in a wet location might need to withstand a hose down for cleaning purposes, if that s something that it would be exposed to.

84 Table This table is valuable for selecting enclosures and for verifying that an appropriate enclosure has been selected. It can be used by the contractor, design professional or authority having jurisdiction

85 Table Table uses the term raintight and rainproof to describe various types of enclosures

86 Table A raintight or watertight enclosure will exclude water or rain

87 Table A rainproof or waterproof enclosure wouldn t necessarily exclude water entirely, but the enclosed equipment can continue to operate succesfully even with a small amount of rain or water entering the enclosure.

88 Section Covers spaces for electrical equipment. It begins with a very general requirement for adequate access and enough working space to permit ready and safe operation and maintenance of all electrical equipment

89 Section In some cases this space may be minimal, just enough to allow a worker to replace, maintain, lubricate, examine or otherwise service equipment

90 Section The general requirements apply to equipment that will be services only after it has been deenergized.

91 Section If the equipment will be serviced, maintained, examined or adjusted while energized, then the applicable section is (A) in which Subsections (1), (2) and (3) describe required minimal dimensions for a three dimensional space.

92 Section Equipment includes nearly all parts of an electrical installation. Article 100 defines equipment as: A general term term, including fittings, devices, appliances, luminaires, apparatus, machinery and the like used as part of or in connection with an electrical installation

93 Section The depth of the working space for energized equipment is described in section (A)(1), based on three conditions: There would be exposed live parts in front of the worker and no live or grounded parts behind

94 Section The depth of the working space for energized equipment is described in section (A)(1), based on three conditions: 1. There would be exposed live parts in front and parts considered to be grounded behind the worker

95 Section The depth of the working space for energized equipment is described in section (A)(1), based on three conditions: 2. There would be exposed live parts in both the front of and behind the worker

96 Section The depth of the working space for energized equipment is described in section (A)(1), based on three conditions: 3. There would be exposed live parts both in front and behind the worker

97 Section The depth required for working space for energized equipment is based on the voltage to ground

98 Section If the voltage to ground is volts, then all three conditions produce the same depth requirement which is 3 feet

99 Section If the voltage is between 150 and 600 volts to ground, then the dimension is greater for condition two 3 feet 6 inches and condition three 4 feet

100 Section Sections and Table (A)(1) cover 600 volts or less. If the voltage is higher than 600 volts, increasing depths for higher voltage are provided by Table (A)

101 Section Table (A) also uses conditions 1,2 and 3 and provides for voltage up to and above 75,000 volts

102 Section (A)(2) addresses the width of the working space to provide enough space for a typical person to stand freely in front of the equipment being worked on

103 Section (A)(2) The minimum width of the working space is the width of the equipment but the width cannot be less than 30 inches wide

104 Section (A)(2) If the equipment is wider than 30 inches, the width requirement equals the width of the equipment. For example if the width of the equipment is 42 inches the width of clear space must also be 42 inches

105 Section (A)(2) If the width of the equipment is less than 30 inches, the minimum width of the working space is still 30 inches.

106 Section (A)(2) The National Electric Code has no requirement that every piece of equipment have its own dedicated, discrete width in front of it, but simply that there be that much width in front of every piece of equipment

107 Section (A)(3) The height of the working space is the height of the equipment but not less than 6 and one half feet

108 Section (B) Once these three dimensional spaces are defined, Section (B) requires that the entire space be kept clear and not used for any kind of storage

109 Section (A)(3) In fact even other parts of the electrical installation are not permitted to occupy the working space, although Section (A)(3) does not allow other electrical equipment above or below the equipment requiring working space to extend up to 6 inches into that working space

110 Section (A)(3)

111 Section (D) Section (D) requires that the working space must be illuminated so work can be done safely and the person working in that space can see what they are doing

112 Section (D) Mandatory illumination is not required to be dedicated to just the working space, to general illumination for the area can be used, but control of the lighting may not be exclusively automatic

113 Section (D) The National Electric Code does not specify a level of illumination but other standards can provide recommendation

114 Section (C)(1) This Section requires at least one entrance of sufficient area for access and egress

115 Section (C)(2) Requires a continuous and unobstructed way of egress travel is subject to different interpretations

116 Section (C)(2) A common interpretation is that it means that the pathway is directly away from the equipment and there are no obstructions, other than a door.

117 Section (C)(2) The National Electric Code does not require or assume that there will be a door. The working space may be part of a larger open area.

118 Section Section requires that for some equipment over 600 volts a means of restricting access to only qualified persons

119 Section (C)(2) When the equipment is over 600 volts the requirement applies to doors within 25 feet of the working space without regard to the ampere rating or physical dimensions of the equipment

120 Review General requirements of the National Electrical Code are included in Article 110, which covers approval, installation and use, access and required space for equipment

121 Review All equipment installed under the National Electrical Code must be approved by the authority having jurisdiction.

122 Review The authority having jurisdiction will prefer that listed equipment be used when possible, because listing means the equipment has been evaluated by an independent agency

123 The National Electric Code addresses the need to interrupt unintended fault current by providing interrupting ratings and short circuit current ratings for equipment

124 Review The National Electric Code also addresses safety through the general requirements that installations must be made in a neat and workmanlike manner

125 Review Also requiring unused openings to be closed up and requiring equipment to be protected from damage from paint or other construction activities

126 Review Equipment must be marked to avoid various hazards, including warnings of flas hazard, marking of available fault current, identification of disconnecting means and accurate labeling of switchboards and panelboards

127 Review National Electrical Code requirements also cover indoor and outdoor equipment enclosures and space requirements for the areas in which equipment is housed.

128 Questions?

(1) Minimum Required. At least one entrance of sufficient area shall be provided to

(1) Minimum Required. At least one entrance of sufficient area shall be provided to (B) Clear Spaces. Working space required by this section shall not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space, if in a passageway