Per the 2017 NEC, what is the largest size insulated solid conductor permitted to be installed into an existing raceway?

Question

It is in the 2017 National Electrical Code book and I need the article and section please

Answer 1

The answer depends on the size and type of conduit. Then you would want to use the the chapter 9 tables in the back of the book. For instance, let's say you were using 1" EMT electrical metallic tubing. Using Table 4 Dimension and Percent Area of Conduit and Tubing, If you wanted to install qty 1 THHN conductor or wire in that conduit you would use 1 wire fill column of 53%. You can see that the area of 53% of the 1" emt conduit inside is 0.416 square inches. So then turn to Table 5 Dimensions of Insulated Conductors... and you will see that a 250 kcmil size thhn insulated conductor has an area of 0.3970 square inches and the next size conductor up is 0.4608 square inches so the 250kcmil conductor would be the largest that would fit per code for wire fill in the 1" EMT.

** Note: I had the 2011 code book handy so the table numbers are from 2011 but I think 2017 is the same but if not it is close and you should be able to figure it out from here.

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