The Optional Calculation Method for a One-Family Dwelling (220.82)

The standard method (earlier lessons) adds up loads piece by piece with lots of little demand factors. The optional method in CEC 220.82 is a simpler shortcut that usually gives a smaller, more realistic service size for a typical modern home. Both are code-legal; the exam expects you to know both.

When you can use it — 220.82(A)

The optional method is allowed for a dwelling served by a 120/240-volt (or 208Y/120-volt), 3-wire service or feeder rated 100 amperes or greater. (CEC 220.82(A))

Step 1 — General loads at 100% / 40% — 220.82(B)

Add up all of these "general" loads at their full value first:

• General lighting: 3 VA/ft² of floor area
• The two small-appliance circuits + laundry circuit: 1,500 VA each = 4,500 VA
• The nameplate rating of every permanently connected appliance — range, oven/cooktop, water heater, dishwasher, disposal, clothes dryer, etc.

Key difference from the standard method: here the range is counted at its full nameplate — you do not use the Table 220.55 "8 kW" shortcut inside the optional method.