The combination of an outlet box and cover plate is intended to create a closed volume that keeps any short circuits, arcing and sparking within the box, and separated from flammable materials nearby in the wall, thereby avoiding a house fire. The National Electrical Code specifies that “plaster, drywall, or plasterboard surfaces that are broken or incomplete around boxes employing a flush-type cover or faceplate shall be repaired so that there will be no gaps or open spaces greater than 3 mm (1/8 inch) at the edge of the box” (NEC 314.21).

    A second NEC code requirement is that “receptacle faceplates (cover plates) shall be installed so as to completely cover the opening and seat against the mounting surface” (NEC 406.6). An oversized faceplate can be used to cover any defects in the wall finish around a box, but not to cover an excessive gap around the box. 

    The receptacle outlet box should also not be mounted more than 1/4” back from wall surface for non-combustible surface, such as drywall (NEC314.20). A box in a wall of flammable material, such as wood, must be flush. Where a box extends forward of the wall surface for the use of a surface plate, a gap around the box is not an issue unless the wall has a fire rating. 

    Home inspectors don’t usually remove receptacle cover plates to check for an excessive gap between the box and adjacent drywall.  But when there is a gap visible around the cover plate, which itself extends past the edge of the box, then there is definitely an opening around the box which needs to be repaired.

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Here’s links to a collection of our other blog posts about ELECTRICAL WIRING:

• Which house appliances need a dedicated electrical circuit?

• Can a short circuit cause a high electric bill?

• Why is it unsafe to bond neutral and ground wiring at subpanels?

• Should I get a lightning rod system to protect my house?

• Why is a strain relief clamp necessary for the cord connection to some electric appliances?  

• Does a wire nut connection need to be wrapped with electrical tape?

• What is the minimum clearance of overhead electric service drop wires above a house roof?

• What are the requirements for NM-cables entering an electric panel box? 

• What is the color code for NM cable (Romex®) sheathing?

• Why is undersize electric wiring in a house dangerous? 

• What causes flickering or blinking lights in a house?

• Why are old electrical components not always "grandfathered" as acceptable by home inspectors?

• How can I find out the size of the electric service to a house?

• Can old electrical wiring go bad inside a wall? 

• What is "knob and tube" wiring?  

• What is the code requirement for receptacle outlets in a closet?

   Visit our ELECTRICAL page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.