NEC Table 300.5

NEC Article 725.136(A)

Low-voltage sensor wiring (Class 2) must be run in separate conduit from line-voltage power wiring per NEC Article 725.136(A). Electromagnetic interference from the 120V power induces noise on the sensor signal, causing erratic readings and unstable control loops on the new DDC system.

NEC Chapter 9 Table 1 & Annex C Table C.1 / Article 358.22

1/2" EMT has only 0.122 sq in of usable area at 40% fill (Chapter 9, Table 4). Each #12 THHN is 0.0133 sq in (Chapter 9, Table 5), so ten conductors require 0.133 sq in — over the 40% limit. NEC Annex C, Table C.1 permits a maximum of 9 #12 THHN in 1/2" EMT.

NEC Chapter 9, Table 1 / Table 5

For three or more conductors, conduit fill is limited to 40% of the conduit's internal cross-sectional area per NEC Chapter 9, Table 1. Five #12 THHN conductors at 0.0133 sq in each = 0.0665 sq in total. The 40% fill for 1/2" EMT is 0.122 sq in. Since 0.0665 < 0.122, this is compliant. The two 90-degree bends total 180 degrees, which is under the 360-degree maximum per NEC 358.26 (EMT bends).

NEC Table 310.16

Per NEC Table 310.16, 10 AWG copper with 60°C insulation (NM-B) is rated for 30 amperes. A 30A dryer circuit using 10/3 NM-B cable (two hots, one neutral, one ground) is standard and code-compliant. The 40-foot run is well within voltage drop guidelines (typically under 3% for branch circuits).