Here’s exactly how I want you to do Step 1 every time, so your service calculation starts on solid ground.

Purpose: Establish the base load from the total floor area.
Rule Reference: CEC Rule 8-110 and 8-200 (a)(i).

1) Understand what you’re measuring

Your total living area is the finished, usable living space in the dwelling unit.
This is the area the Code uses to establish the base load (lighting + general-use receptacles).

2) Identify what to include

Include finished areas used for normal living, such as:

Living rooms, dining rooms, bedrooms

Kitchens, hallways, bathrooms

Finished basements (if finished as living space)

Finished portions of any level (including finished lofts/attics, if they are truly living space)

Rule of thumb: If it’s finished and people live/use it daily, include it.

3) Identify what to exclude

Do not include areas that are not part of the living space, such as:

Garages (attached or detached)

Unfinished basements

Crawl spaces

Unfinished attics

Porches/decks/sunrooms that aren’t finished living space

Exterior storage or mechanical-only rooms (when not considered living space)

Rule of thumb: If it’s storage, mechanical, unfinished, or outdoor space—exclude it.

 

4) Measure each level (or section) separately

Measure each floor or section as a rectangle (or break it into rectangles), using:

Length × Width = Area

Use the internal dimensions (the way your worksheet is set up).

Example format:

First floor: 14 m × 9 m = 126 m²

Second floor: 14 m × 9 m = 126 m²

Basement finished portion: 14 m × 9 m × 0.75 = 94.5 m²

5) Handle “partial finished” areas correctly

If only part of a space is finished (like a basement that’s 75% finished), you must:

Calculate full area, then multiply by the finished percentage

Example: 14 × 9 = 126 m²

126. × 0.75 = 94.5 m² finished living area

6) Add all included areas to get the total living area

Now sum every included section:

Total living area =
126 + 126 + 94.5 = 346.5 m²

7) Quick self-check before moving to Step 2

Before you leave Step 1, confirm:

✅ You did not include the garage or unfinished spaces

✅ You used internal dimensions consistently

✅ You applied the correct percentage for partially finished areas

✅ Your total area looks reasonable for the dwelling type

Example:

Unit A: 14 m × 9 m = 126 m²

Unit B: 14 m × 9 m = 126 m²

Unit C: 14 m × 9 m × 0.75 (finished portion) = 94.5 m²

Total Living Area:

→ 126 + 126 + 94.5 = 346.5 m²

 

Calculation:

55 – 90 = 257.55 m² → 1000 W

55 – 90 = 167.55 m² → 1000 W

55 – 90 = 77.55 m² → 1000 W

Total Base Load:8000 W

 

Tip: Each “part thereof” of 90 m² still counts for a full 1000 W increment.