406.5 Receptacle Mounting.

The machine screws that come with the receptacle should be used.
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The machine screws that come with the receptacle should be used.

Code Change Summary: Code language was added to address using proper screws for mounting receptacles.

A new receptacle comes from the factory with the proper attachment screws. All too often, a poor box installation creates the need for longer screws. When a box is recessed too far behind the wall finish, sometimes the factory screws are not long enough to reach the mounting holes.

 A common violation occurs when an installer uses longer screws that were never intended to be used for receptacle mounting, such as sheetrock screws found on the job site that were dropped by the drywall installers.

Do they work? Yes. Is it right? No.

Now, specific code language in the 2014 NEC® requires the correct attachment screws to be used when attaching a receptacle to a box.

Below is a preview of the NEC®.  See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on the “free access” tab and select the applicable year of NFPA 70 (National Electrical code).

2011 Code language:

406.5 Receptacle Mounting. Receptacles shall be mounted in boxes or assemblies designed for the purpose, and such boxes or assemblies shall be securely fastened in place unless otherwise permitted elsewhere in this Code.

2014 Code Language:

406.5 Receptacle Mounting. Receptacles shall be mounted in identified boxes or assemblies. The boxes or assemblies shall be securely fastened in place unless otherwise permitted elsewhere in this Code. Screws used for the purpose of attaching receptacles to a box shall be of the type provided with a listed receptacle, or shall be machine screws having 32 threads per inch or part of listed assemblies or systems, in accordance with the manufacturer’s instructions.

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406.5 Receptacle Mounting.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Which of the following fasteners is permitted to be used to attach a receptacle to a box?

A: Coarse thread sheetrock screws.
B: Machine screws having 24 threads per inch.
C: Machine screws having 32 threads per inch.
D: Self-tapping screws.
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