Do not get knocked out from a missing Knockouts (or unused openings).

Submitted by DonHester on Mon, 10/05/2015 - 08:03.

Do not get knocked out from a missing Knockouts (or unused openings).

Wenatchee Home Inspection

As home inspectors we see them all the time ”unused openings” in electrical boxes and electric panels (panelboards) that should always be covered.

Plug for knockouts

These openings create potential shock hazards, they might not properly contain a fire that could occur within the box, and can admit unwanted visitors such as mice.

Bad day for this little guy

I actually know of a home that burned to the ground from a missing knockout.

From the 2014 NEC Handbook-

“The requirement of 110.12(A) for closing unused openings (other than those provided for equipment mounting or drainage) applies to all electrical enclosures, including panelboard cabinets, switchgear, and switchboard enclosures. An unused opening may exist as a result of a renovation or an alteration of existing equipment. These two requirements are necessary to restore the electrical equipment enclosure integrity to a condition that minimizes the possibility of an escaping arc, spark, or molten metal igniting surrounding combustible material and also minimizes the potential for accidental contact with live parts.”

Here is where the electrical code has the requirements-

2014 NEC - 110.12 Mechanical Execution of Work.

Electrical equipment shall be installed in a neat and workmanlike manner.

FPN: Accepted industry practices are described in ANSI/NECA 1-2006, Standard Practices for Good Workmanship in Electrical Contracting, and other ANSI-approved installation standards.

(A) Unused Openings.

Unused openings, other than those intended for the operation of equipment, those intended for mounting purposes, or those permitted as part of the design for listed equipment, shall be closed to afford protection substantially equivalent to the wall of the equipment. Where metallic plugs or plates are used with nonmetallic enclosures, they shall be recessed at least 6 mm (¼ in.) from the outer surface of the enclosure.

From the 2014 NEC handbook-

“This section requires all unused openings other than those openings used for mounting, cooling, or drainage to be closed up.”

Filler plates for panelboards

2014 NEC - 408.7 Unused Openings

Unused openings for circuit breakers and switches shall be closed using identified closures, or other approved means that provide protection substantially equivalent to the wall of the enclosure.

“Codes are minimum standards and most houses are built by the lowest bidder”

Don Hester

NCW Home Inspections, LLC is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…

Your Wenatchee and Chelan Professional Real Estate, Home and Structural Pest Inspection Service

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www.ncwhomeinspections.com 509-670-9572

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Do not get knocked out from a missing Knockouts (or unused openings).