1、AN AMERICAN NATIONAL STANDARDNECA 1-2015Standard forGood Workmanshipin Electrical ConstructionPublished byNational Electrical Contractors AssociationStandard forGood Workmanshipin Electrical ConstructionNECA 1-2015An AmericanNational StandardPublished byNational Electrical Contractors Associationn i
2、iNOTICE OF COPYRIGHTThis document is copyrighted by NECAReproduction of these documents either in hard copy or soft (including posting on the web) is prohibited without copyright permission. For copyright permission to reproduce portions of this document, please contact NECA Standards also in a hori
3、zontal or vertical position as intended.b) All materials shall be firmly secured in place, adequately supported, and permanent. Materialsembedded in concrete or masonry or otherwise part of the structure are considered sufficiently supported. c) All hardware, fittings, and accessories shall be of a
4、type designed, intended and appropriate for use and complement the items with which they are used. d) All materials and equipment including hangers, supports, fasteners or fittings, and accessories shall have corrosion protection suitable for the atmosphere in which they are installed (whether locat
5、ed indoors or outdoors). Care shall be taken during the installation to assure the integrity of the corrosion protection. Damaged corrosion protection shall be repaired during or after installation.e) All screws, bolts, nuts, clamps, fittings or other fastening devices shall be made up tight in acco
6、rdance with manufacturers and/or listing instructions.f) Plans and specifications shall be carefully followed when installing equipment. NOTE: Local building codes may have seismic requirements that affect equipment installation. Installers shall consult these codes or coordinate with the general co
7、ntractor prior to installing equipment.3. General RequirementsFigure 1 (Courtesy of Cogburn Bros., Inc.)n 41. ScopePermanence and neat appearance, a part of good workmanship, require that consideration be given to the type of atmosphere surrounding anchors and fasteners. Anchors and fasteners shall
8、be non-corrosive or have adequate corrosion resistant coatings or treatment. Weather conditions must be considered for outdoor locations, but there are also indoor locations that may be wet or damp. Fumes from industrial processing also may cause corrosive atmospheres. The possibility of corrosion d
9、ue to incompatibility between dissimilar metals must also be considered. Corrosion and deterioration is addressed in Section 300.6 of the NEC.a) All anchors and fasteners shall be of a type designed for the purpose and rated capable of adequately and safely securing the item on the base material in
10、which the anchor or fastener is used. Selection shall be based on the amount and type of load, base material, safe working load and atmosphere.b) In addition to the weight of the material, consideration should also be given to vibration, such as with motors or fans; variable loading resulting from i
11、nternal or external forces, such as operation of safety switches or circuit breakers; and shock load, when possible (see Figure 2).c) Anchors or fasteners used shall be a type designed and intended for use in the base material to which the material or support is to be attached. Generally, screws are
12、 used on wood, masonry anchors on concrete or brick, toggle bolts or similar on hollow walls, machine screws, bolts or welded studs on steel. Nails are normally used only for temporary support or for light loads, such as nonmetallic outlet and device boxes, in wood frame construction.4. Anchors and
13、FastenersFigure 2 (Courtesy of IAEI)5 n1. ScopeThe weight of the hanger or support must be considered as part of the total load. The total load also includes the materials within an enclosure. For example, the weight of the conductors in a raceway or junction or pull box shall be added to the load o
14、f the raceway or box. External forces such as vibration, operation of equipment, such as switch handles, or possible shock load shall also be considered. Safe working load shall be determined by applying recognized safety factors to the rated strength of the complete assembly and shall be based on t
15、he weakest component member. a) Hangers and supports shall be used to properly and firmly support electrical materials or equipment in a safe and permanent manner. They may be standard manufactured items or fabricated in the shop or on the job site (see Figure 3). b) They shall be of a type designed
16、 or appropriate for the purpose, have a neat and finished appearance and complement the installation.c) Job fabricated hangers and supports shall be made from standard structural shapes and hardware or systems of shapes, fittings and hardware designed for the purpose. One example would be angle iron
17、s. d) All bolts, screws, nuts, and other threaded devices shall have standard threads and heads so that they do not require special tools and may be readily replaced when necessary unless required for tamper-proof installation.e) All threads shall be fully engaged (or covered) and all parts made up
18、tight.f) The selection of hangers and supports shall be based on the following criteria:1. Amount and type of load2. Safe working load3. Atmosphere4. Manufacturers recommendations5. Job specifications6. Listing for the application (where applicable)7. Spacing intervals required by the NEC (where app
19、licable).g) Hangers and supports, whether standard manufactured items or job fabricated, shall have corrosion protection suitable for the atmosphere in which they are installed (whether located indoors or outdoors). Care shall be taken during the installation to assure the integrity of corrosion pro
20、tection. Damaged corrosion protection shall be repaired during or after installation.h) When hangers and supports that have corrosion protection are field cut, the material shall be protected by field application of an approved zinc-enriched paint or similar sealant in accordance with 300.6.5. Hange
21、rs and SupportsFigure 3 (Courtesy of IAEI)n 6NECA 1 Standard for Good Workmanship in Electrical Constructioni) Care must be taken to prevent corrosion that might result from the use of dissimilar metals in damp or wet locations. Damaged corrosion protection coatings shall be repaired during or after
22、 installation.j) Hangers and supports shall be adequately and safely attached to the building structure or structural member.k) The equipment or materials to be supported shall be securely fastened to the supporting means with material suitable for the purpose.7 n1. Scopea) Outlet and device boxes s
23、hall be of a type designed for the use and location (see Figure 4). b) Outlet and device boxes shall be securely and rigidly attached or supported plumb, level, and true. c) Box supports, hangers or brackets, when used, shall be of a type designed or suitable for the type of box used and the buildin
24、g structural member to which they are attached. In determining the type of support or fastener, consider the total load caused by any device or equipment, such as lighting fixtures, which are in turn supported by the outlet box (see Figure 5).d) Outlet and device boxes and their covers shall have co
25、rrosion protection suitable for the atmosphere in which they are installed. Where necessary, gaskets shall be used to prevent the entrance of moisture. e) Installation of outlet and device boxes shall be coordinated with other trades, such as drywall and painting.f) Outlet and device boxes shall be
26、protected to prevent entrance of foreign matter. Plaster and debris shall be thoroughly cleaned from the box before the conductors are installed.g) Generally, single-gang outlet and device boxes for switches shall be mounted with the long axis vertical.h) Generally, boxes for receptacles shall be mo
27、unted either vertically or horizontally, but consistently throughout the structure.i) Boxes of three or more gangs shall be mounted with the long axis (dimension) horizontal. The boxes shall be located so that the cover or device plate will not span different types of building finishes either vertic
28、ally or horizontally.j) Boxes for switches near doors shall be located on the side opposite the hinge and close to the door trim. k) Covers for outlet boxes shall be of a type designed, intended and appropriate for the use and location, and have suitable corrosion protection. Plastic device plates s
29、hall not be used as covers for surface mounted boxes.6. Outlet BoxesFigure 4 (Courtesy of IAEI) Figure 5 (Courtesy of IAEI)n 81. Scopea) Junction and pull boxes shall be used where necessary to facilitate the pulling of wire or cable.Section 314.28(A) in the NEC provides minimum sizing requirements
30、for junction or pull boxes used in wiring systems containing conductors in sizes 4 AWG and larger (see Figures 6a and 6b).b) Consideration shall be given to the size and number of conductors, number of bends in the raceway, and the need for support of conductors in vertical raceways.c) Junction and
31、pull boxes shall be of a type intended or suitable for the use and location. They may be standard manufactured items or custom designed and fabricated to meet the particular requirements.d) Junction and pull boxes including hinges or screws used to fasten the cover shall have corrosion protection su
32、itable for the atmosphere in which they are installed.e) Junction and pull boxes shall be firmly and securely fastened to or supported from the building structure or structural member. In determining the type of fastener, hanger, or support, consideration must be given to the load caused by any cond
33、uctors supported by the box and any load that might be caused by external forces.f) Raceways shall be arranged to provide the longest sweep or radius for the conductors. g) Covers for large junction or pull boxes that are that are 1.8 m2(6 ft2) or larger should be hinged or sectionalized to facilita
34、te removal and replacement. When the cover is sectionalized, cross bracing shall be provided to fasten the sections of the cover at the seams.7. Junction and Pull BoxesFigure 6a Figure 6b9 n1. Scopea) Raceways shall be firmly and securely fastened to or supported from the building structure or a str
35、uctural member or embedded in concrete or masonry. Tables 1a and 1b (next page) list recommended spacing of supports for vertical and horizontal raceways.b) Hangers and supports shall be of a type compatible with and suitable for the intended use. They may be standard manufactured items or job fabri
36、cated. Consideration must be given to the weight of the enclosed conductors when selecting supports and fastening means.8. RacewaysTable 1a: Spacing of Conduit Supports*Conduit Trade No. of Conductors Location Maximum Support Size (inches) in Run Spacing (feet)HORIZONTAL RUNS12, 34 1 or 2 Flat ceili
37、ng or wall 5 12, 34 1 or 2 Where it is difficult to provide supports 7 except at intervals fixed by the building construction 12, 34 3 or more Any location 7 1 and larger 1 or 2 Flat ceiling or wall 6 1 and larger 1 or 2 Where it is difficult to provide supports 10 except at intervals fixed by the b
38、uilding construction 1 and larger 3 or more Any location 10 Any Concealed 10VERTICAL RUNS12, 34 Exposed 7 1, 114 Exposed 8 112 and larger Exposed 10 Up to 2 Shaftway 14 212 and larger Shaftway 28 Any Concealed 101. A support shall be provided for exposed or concealed raceway as close as practical to
39、 and not exceeding one foot from an unsupported box or access fitting. In horizontal runs, a support at a box or access fitting may be omitted when the box or access fitting is independently supported and the raceway terminal is not made with a Chase nipple or threadless box connector.2. In vertical
40、 runs, the load produced by the weight of the raceway and the enclosed conductors shall not be carried by the raceway terminals but shall be carried entirely by the conduit supports.* (The National Electrical Code did not provide specific requirements for the support of rigid metal conduit until the
41、 1965 Edition. The table of spacings in the Code applied to sizes 12” through 3” only and was expanded to cover up to 6” in the 1968 Edition. The spacing requirements of this standard were originally published by the National Electrical Contractors Association in 1928 as part of the “Electragist Sta
42、ndards for Wiring Installations.” They have been frequently quoted and included in handbooks on electrical installations. In some specifics they are more restrictive than the requirements of the National Electrical Code.) n 10NECA 1 Standard for Good Workmanship in Electrical Constructionc) Care sha
43、ll be taken to prevent the entrance of foreign matter into raceways and they shall be cleaned if necessary before pulling the conductors.d) Stub-ups shall be protected from damage and carefully re-bent where necessary. Bends and offsets shall be carefully made so that the inside diameter is not effe
44、ctively reduced. Unless otherwise required, the legs of a bend shall be in the same plane, and the straight legs of offsets shall be parallel.e) All raceway fittings shall be of a type compatible with the raceway and suitable for the use and location. f) Unless otherwise specified, concealed raceway
45、s Figure 7 (Courtesy of Cogburn Bothers, Inc.)Table 1b: Spacing of Conduit Supports*Conduit Trade Size No. of Conductors Location Maximum Support (metric designator) in Run Spacing (meters)HORIZONTAL RUNS16, 21 1 or 2 Flat ceiling or wall 1.5 16, 21 1 or 2 Where it is difficult to provide supports 2
46、.1 except at intervals fixed by the building construction 16, 21 3 or more Any location 2.1 27 and larger 1 or 2 Flat ceiling or wall 1.8 27 and larger 1 or 2 Where it is difficult to provide supports 3 except at intervals fixed by the building construction 27 and larger 3 or more Any location 3 Any
47、 Concealed 3VERTICAL RUNS16, 21 Exposed 2.1 27, 35 Exposed 2.5 41 and larger Exposed 3 Up to 53 Shaftway 4.3 63 and larger Shaftway 8.5 Any Concealed 31. A support shall be provided for exposed or concealed raceway as close as practical to and not exceeding one foot from an unsupported box or access
48、 fitting. In horizontal runs, a support at a box or access fitting may be omitted when the box or access fitting is independently supported and the raceway terminal is not made with a Chase nipple or threadless box connector.2. In vertical runs, the load produced by the weight of the raceway and the
49、 enclosed conductors shall not be carried by the raceway terminals but shall be carried entirely by the conduit supports.* (The National Electrical Code did not provide specific requirements for the support of rigid metal conduit until the 1965 Edition. The table of spacings in the Code applied to sizes 12” through 3” only and was expanded to cover up to 6” in the 1968 Edition. The spacing requirements of this standard were originally published by the National Electrical Contractors Association in 1928 as part of the “Electragist Sta
