Change Summary

• Screws for receptacles must be either 6-32 machine screws matching the thread gage or size that is integral to the box or part of a listed assembly or system.
• Fastening means in accordance with manufacturer’s installation instructions are acceptable.
• The first sentence has been revised and a new last sentence has been added to this section

Expert Analysis

The first sentence of this section has been revised to that require receptacles be fastened to identified boxes or assemblies. A new last sentence specifies that screws used for attaching receptacles to the box be machine screws of 32 threads per inch, or part of a listed assembly or system. Use of drywall screws and other screws that are not intended for fastening receptacles or other equipment to boxes is unacceptable and can result in damage to boxes and inadequate fastening of devices. Manufacturer’s installation instructions usually cover this in most cases for listed boxes and equipment, but the additional text helps clarify this requirement. Listed boxes or assemblies could specify use of thread-forming screws in nonmetallic outlet boxes and applicable product standards might recognize use thread forming screws for attachment of receptacles provided they meet the performance requirements in the applicable standard. This type of screw is typically used with nonmetallic boxes and is supplied with the box. Section 110.3(B) covers this in the requirement to install devices in accordance with any instructions provided in the listing or labeling. Drywall screws and other inappropriate screws are not permitted for use in fastening receptacles to boxes or plaster rings.