National Electrical Installation Standards

Standards as High as Your Own

Wednesday, January 23, 2019


What type is wire should be used inside the core of a 13” block wall?

Dave Guzofsky



Hey Dave thanks for your question, 13 inch concrete blocks seem to be an odd size. Single conductors can only be installed as part of a recognized wiring method as stated in 300.3(A). The wiring method and contained conductors need to be suitable for the location and comply with the Uses Permitted XXX.10 and Uses Not Permitted XXX.12 of the respective wiring method article in Chapter 3. For example, Nonmetallic-Sheathed Cable is allowed in air voids of masonry block or tile walls as stated in 334.10(A)(2). But the wall would need to be a dry location to comply with 334.10(A)(1) and the conditions in 334.10 and 334.12 also need to be complied with. Alternatively, other wiring methods in Chapter 3 can be used.


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