Raceway Size Calculator (NEC EMT)

This calculator finds the smallest EMT trade size for a mix of AV cables, the way an integrator sizes a home run from a wall plate to the rack. Pick up to three cable types, or enter a custom diameter, and the calculator sums their cross-section at the outside diameters the manufacturers state (Belden category, coax, microphone, speaker and control cables; Extron HDMI, USB-C, DisplayPort and USB assemblies; Liberty stereo mini and RCA assemblies), applies the NEC Chapter 9 Table 1 fill limit keyed to the number of cables installed (53 percent for one, 31 percent for two, 40 percent for three or more, the flat AVIXA maxima), and reads the Table 4 EMT areas up from the trade size 3/4 AV minimum. A factory-terminated head is pulled with its cable, so the calculator also checks that the head passes the tubing's inside diameter across its corners at the dimensions the manufacturer states, and says so when the head rather than the fill sets the size. Fittings and bends are not modelled, and a power cable never shares the AV raceway.