1、NEMA Standards PublicationNational Electrical Manufacturers AssociationANSI/NEMA OS 2-2013Nonmetallic Outlet Boxes, Device Boxes, Covers, and Box SupportsANSI/NEMA OS 2-2013 Nonmetallic Outlet Boxes, Device Boxes, Covers, and Box Supports Published by National Electrical Manufacturers Association 13
2、00 North 17th Street, Suite 900 Rosslyn, VA 22209 www.nema.org Approval Date: April 15, 2014 Published: April 23, 2014 Copyright 2014 by National Electrical Manufacturers Association. All rights including translation into other languages, reserved under the Universal Copyright Convention, the Berne
3、Convention or the Protection of Literary and Artistic Works, and the International and Pan American Copyright Conventions. OS 2-2013 Page 2 2014 National Electrical Manufacturers Association NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus o
4、f persons engaged in the development and approval of the document at the time it was developed. Consensus does not necessarily mean that there is unanimous agreement among every person participating in the development of this document. The National Electrical Manufacturers Association (NEMA) standar
5、ds and guideline publications, of which the document contained herein is one, are developed through a voluntary consensus standards development process. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. While
6、NEMA administers the process and establishes rules to promote fairness in the development of consensus, it does not write the document and it does not independently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards
7、and guideline publications. NEMA disclaims liability for any personal injury, property, or other damages of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, application, or reliance on this document. NEMA
8、 disclaims and makes no guaranty or warranty, expressed or implied, as to the accuracy or completeness of any information published herein, and disclaims and makes no warranty that the information in this document will fulfill any of your particular purposes or needs. NEMA does not undertake to guar
9、antee the performance of any individual manufacturer or sellers products or services by virtue of this standard or guide. In publishing and making this document available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity, nor is NEMA undertaki
10、ng to perform any duty owed by any person or entity to someone else. Anyone using this document should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Information an
11、d other standards on the topic covered by this publication may be available from other sources, which the user may wish to consult for additional views or information not covered by this publication. NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this d
12、ocument. NEMA does not certify, test, or inspect products, designs, or installations for safety or health purposes. Any certification or other statement of compliance with any health or safety-related information in this document shall not be attributable to NEMA and is solely the responsibility of
13、the certifier or maker of the statement. NEMA OS 2-2013 Page 3 2014 National Electrical Manufacturers Association TABLE OF CONTENTS Page Foreword 5 Section 1 General . 7 1.1 Scope . 7 1.2 Normative References . 7 1.3 Definitions 7 Section 2 General Standards . 11 2.1 Material 11 2.2 Corrosion Protec
14、tion 11 2.3 Screws . 11 2.4 Openings . 11 2.4.1 Cable-Size Knockouts . 11 2.4.2 Knockouts for Conduit or Tubing . 12 2.4.3 Clamps 12 2.5 Supports 12 2.6 Boxes for Supporting Equipment or Accessories 12 2.6.1 Boxes for Luminaire Support . 13 2.6.2 Boxes for Ceiling-Suspended Fan Support . 13 2.7 Devi
15、ce Boxes . 13 2.8 Boxes and Mounts for Other Devices and Accessories 13 2.9 Boxes for High- and Low-Voltage Circuits . 13 2.10 Marking 13 2.10.1 General 13 2.10.2 Boxes for Supporting Equipment and Accessories . 13 2.10.3 Cable Clamps 13 2.11 Grounding 14 Section 3 Specific Requirements 15 3.1 Gener
16、al 15 3.2 Index to Figures . 15 Tables 1 Screws Commonly Used In Conjunction with Outlet Boxes, Device Boxes, and Covers 11 2 Diameter of Knockouts 12 Figures 1 Single Gang Flush or Surface Mounted Nonmetallic Device Box . 17 2 Two Gang Flush Mounted Nonmetallic Device Box 18 3 Three Gang Flush Moun
17、ted Nonmetallic Device Box 19 4 Four Gang Flush Mounted Nonmetallic Device Box 20 5 Single Gang Flush Mounted Nonmetallic Device Box with Plaster Ears . 21 6 Two Gang Flush Mounted Nonmetallic Device Box with Plaster Ears 22 7 Three Gang Flush Mounted Nonmetallic Device Box with Plaster Ears 23 8 Si
18、ngle Gang Offset Flush Mounted Nonmetallic Device Box with Plaster Ears 24 9 Nominal 3-1/4” / 3-1/2” Round or Octagonal Nonmetallic Device Box 25 10 Nominal 4” Round Or Octagonal Nonmetallic Device Box 26 OS 2-2013 Page 4 2014 National Electrical Manufacturers Association 11 Nominal 3-1/4” / 3-1/2”
19、Round or Octagonal Nonmetallic Device Box with Flange . 27 12 Nominal 4” Round or Octagonal Nonmetallic Device Box with Flange 28 13 Nominal 4” Square Nonmetallic Device Box 29 14 Flat Blank Nonmetallic Cover for Nominal 3-1/4” And 3-1/2” Round or Octagonal Outlet Box . 30 15 Flat Blank Nonmetallic
20、Cover for Nominal 3-1/4”, 3-1/2”, and 4” Round or Octagonal Outlet Box . 31 16 Raised Blank or Cord Drop Nonmetallic Cover for 3-1/4”, 3-1/2”, and 4” Round or Octagonal Outlet Box 32 17 Flat Blank Nonmetallic Cover for 4” Square Outlet Box 33 18 Nonmetallic Blank or Pendant Cover for Surface Mounted
21、 Device Boxes 34 19 Nonmetallic Duplex Receptacle Cover for Surface Mounted Device Boxes . 35 20 Nonmetallic Single Receptacle Cover for Surface Mounted Device Boxes . 36 21 Nonmetallic Toggle Switch Cover for Surface Mounted Device Boxes . 37 22 Raised Fixture Attachment Nonmetallic Cover for 4” Ro
22、und or Octagonal Outlet Box . 38 23 Raised Fixture Attachment Nonmetallic Cover for 4” Square Outlet Box 39 24 Raised Single-Device Nonmetallic Cover for 4” Square Outlet Box 40 25 Raised Two-Device Nonmetallic Cover for 4” Square Outlet Box . 41 26 Alternate Cover Mounting Hole(s), Slot(s) Configur
23、ations . 42 27 Alternate Ear Configurations 43 28 Alternate Knockout Configurations 44 NEMA OS 2-2013 Page 5 2014 National Electrical Manufacturers Association Foreword The purpose of this standards publication is to provide a guide for the types and sizes of nonmetallic boxes and supports that are
24、in general use. The standards present dimensional data needed for the safety and convenience of interchangeability with associated equipment. All items when properly installed and properly used contribute to safety. Properly manufactured boxes and covers are, however, only one factor in minimizing t
25、he hazards, which may be associated with the use of electricity. The reduction of hazards involves the joint efforts of various equipment manufacturers, the system designer, the installer, and the user. Information is provided herein to assist users and others in the proper selection of boxes and co
26、vers. The manufacturer has limited or no control over the following factors, which are vital to a safe installation: a. Environmental conditions b. System design c. Equipment selection and application d. Installation e. Operating practices f. Maintenance This publication is not intended to instruct
27、the user of the boxes and covers with regard to these factors, except insofar as suitable equipment to meet needs can be recognized in this publication. These standards are necessarily limited to defining the construction requirements for the products covered herein. The publication has been promulg
28、ated with a view towards reducing the hazard to persons and property when boxes and covers conforming to these standards are properly selected and installed in accordance with the National Electrical Code. OS 2-2013 revises and supersedes OS 2-2008 and its revision OS 2-2008 (R2010). This standard i
29、s reviewed with input obtained from independent testing laboratories and major consumer representatives. It is also reviewed periodically by the Outlet and Switch Box Section of NEMA so that it will be kept up to date with advancing technology. Comments are welcomed and should be sent to: Senior Tec
30、hnical Director, Operations National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, Virginia 22209 OS 2-2013 Page 6 2014 National Electrical Manufacturers Association This standard was developed by the Outlet and Switch Box Section. Section approval of the standard d
31、oes not necessarily imply that all section members voted for its approval or participated in its development. At the time this standard was approved, the Outlet and Switch Box Section was composed of the following members: 2D2C, Inc. Kitchener, ON Canada Allied Moulded Products, Inc. Bryan, OH Arlin
32、gton Industries, Inc. Scranton, PA Eaton Cooper B-Line Highland, IL Eaton Cooper Crouse-Hinds Syracuse, NY EGS Electrical Group Skokie, IL ERICO Solon, OH Hubbell Incorporated Shelton, CT IPEX USA LLC Mississauga, ON Canada Legrand/Pass cabinets or cutout boxes; floor boxes; flush device cover plate
33、s; boxes, plates, and covers designed for use with surface metal or surface nonmetallic raceway systems only; and boxes larger than 1650 cm (100 cu. in.) in volume, except multiple gang device boxes. 1.2 NORMATIVE REFERENCES The following publications are adopted in part, by reference in this public
34、ation, and are available from the organizations below. Unless otherwise noted, references are to the most recent edition. National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, VA 22209 NEMA OS 3 Selection and Installation Guidelines for Electrical Outlet Boxes Nati
35、onal Fire Protection Association 1 Batterymarch Park Quincy, MA 02169 ANSI/NFPA 70 National Electrical Code Underwriters Laboratories LLC 333 Pfingsten Road Northbrook, IL 60062 ANSI/UL 514C Standard for Nonmetallic Outlet Boxes, Flush Device Boxes and Covers 1.3 DEFINITIONS blank cover: an outlet b
36、ox cover having no knockouts or openings, other than those used to mount to a box. These covers complete the enclosure. blank/knockout cover: an outlet box cover that contains a knockout which can be removed to accommodate a fitting for a pendant cord, etc. When left in place it may serve as a blank
37、 cover. OS 2-2013 Page 8 2014 National Electrical Manufacturers Association box (electrical): part of an enclosure provided with means for mounting a cover, cover-plate, accessory, etc. box extender: a component installed in or on a box that is mounted in a finished structure intended to extend the
38、electrical enclosure up to the new finished surface. The box extender rests on the edge of the existing box (fixed depth) or extends into the box (adjustable depth). The flange of the box extender, if provided, rests on the finished surface. box support: a means (e.g., bracket) for securing an outle
39、t or device box to the building structure or finished surface. Supports can be an integral part of the box, attached to the box, or entirely separate. bracket: a box support for securing an outlet box or device box in place in walls or ceilings, or to wall studs, building structures, or structural m
40、embers. cable box: an outlet box typically provided with clamps for use with metallic or nonmetallic cables or flexible nonmetallic tubing, or any combination of said cables and tubing. (See outlet box.) clamp: a part of or an accessory to a cable box to secure metallic or nonmetallic cables or flex
41、ible nonmetallic tubing (Loom), or any combination of said cables and tubing to the box. concrete box: an outlet box especially intended for support in concrete, typically constructed to allow end-to-end extension and the application of covers on two sides. This box is not intended for floor install
42、ation. conduit box: an outlet box designed with circular knockouts for conduits or fittings for conduit, tubing or cable. device box: a box which is designed to receive and support switches, receptacles, and similar devices. The term “device box” includes the following specific types: a. Single gang
43、fixed sides, accommodates a single device b. Two gangfixed sides, accommodates up to two devices c. Three gangfixed sides, accommodates up to three devices d. Four gangfixed sides, accommodates up to four devices e. Gangablepermits the removal of one or both sides of the box to join (or gang) as man
44、y sections as required device mounting cover: a device box cover that provides a mounting platform for a wiring device. The device is mounted on top of the cover. The cover may be raised. These covers are also sometimes referred to as mud rings. A wallplate is required to complete the enclosure. exp
45、osed work cover: a device box cover that is typically raised having cutouts to accept and support wiring devices. The devices are mounted to the underside of the cover. These covers also complete the enclosure. flush-mounted box: a box that is so designed as to have a minimal front projection from t
46、he surface surrounding the box opening. hung-ceiling box: a box that consists of a ring and a back plate with supporting bars for use with rigid nonmetallic conduit, electrical nonmetallic tubing, flexible nonmetallic tubing, or nonmetallic sheathed cable above suspended ceilings. junction box: a ju
47、nction box with a volume up to 1650 cm (100 cu. in.) or less is considered an outlet box. knockout: a circular portion in the wall of a box or cover that can be removed readily in order to provide an opening for the entry of tubing, conduit, or a fitting. NEMA OS 2-2013 Page 9 2014 National Electric
48、al Manufacturers Association knockout-cable size: a circular or non-circular portion in the wall of a box for entry of cable without use of a fitting. listed: equipment, materials, or services included in a list published by an organization that is acceptable to the authority having jurisdiction and
49、 concerned with evaluation of products or services, that maintains periodic inspection of production of listed equipment or materials or periodic evaluation of services, and whose listing states that the equipment, material, or services either meets appropriate designated standards or has been tested and found suitable for a specified purpose. outlet box: a box used in an electrical wiring system for containing wire, taps, splices, or devices. It has provisions for the entry of conduit, tubing, or cable assemblies and for the attachment of a separate cover, which i
