National Electrical Installation Standards

Standards as High as Your Own

Monday, December 25, 2017


Re: CQD answer published December 20 and 8, 2017 - Physical Damage Protection 1

I don't understand Exhibit 300.1 in the 2017 handbook. Why these types of plates are approved and listed when they do not cover the sides of the stud an 1 1/4" both ways. I know the picture is pertaining to the thickness of the metal. But why show a picture that is in my mind a clear code violation. And why are these plates listed and approved like this. Or am I wrong in assuming the side of the 2 by 4 studs needs to be protected?




Hey Steve thanks for your follow up question you make an interesting point. The wording is different regarding bored holes compared to installations that are parallel to framing members. Cables installed parallel to framing members and furring strips must be at least 1 1/4 inches from the nearest edge of the framing member or furring strip, where nails or screws are likely to penetrate as stated in 300.4(D). The edge of holes in "framing members" must be at least 1 1/4 inches from the nearest edge as stated in 300.4(A)(1). If the 1 1/4 distance is not maintained a steel plate of other means of physical protection that is at least 1/16 inch thick and of appropriate length and width to cover the wiring area, must be provided. Exception 2 in both subdivisions allows a plate to be less than 1/16 inch thick if it is listed and marked as providing equal or better protection. For cables installed through framing members there is no wording that specifies a distance beyond the framing member (side) where physical protection is necessary. Exhibit 300.1 in the 2017 NFPA NEC Handbook is an example of a commonly accepted method of protection.

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