Dwelling Load Calculations in the 2023 NEC

This is where the calculation items earn their name: the Florida DBPR blueprint puts load knowledge and load calculations under Services, Service Equipment and Separately Derived Systems, and the Residential exam leans on the dwelling methods heavily. Everything below is from the 2023 text — Article 220 (Article 220 is still Article 220 in the 2023 edition), with the 2023 values: 3 VA/ft², first 10 kVA in the optional method, 7,200 W EVSE, and the 2023 Table 220.54.

1. Housekeeping rules — 220.5 and 220.60

• Nominal voltages to use: 120, 120/240, 208Y/120, 240, 347, 480Y/277, 480, 600Y/347, 600 (220.5(A)).
• Fractions of an ampere: below 0.5 drop it; 0.5 and above round up to the next whole ampere (220.5(B)).
• Floor area: outside dimensions; for dwellings, exclude open porches and unfinished spaces not adaptable for future habitable use (220.5(C)).
• Continuous loads: the 125 % factor belongs to conductor and OCPD sizing (210.19/210.20, 215.2/215.3, 230.42(A)); Table 220.42(A) already builds it into the non-dwelling lighting unit loads, and the dwelling 3 VA/ft² is not multiplied.
• Noncoincident loads (220.60): where two loads can't run at the same time, use only the larger (the A/C-versus-heat rule). Where a motor or A/C load is part of the comparison and is not the larger load, compare using 125 % of that motor or A/C load.