6.2 Domestic Table C1 Demand Factors

Domestic Table C1 Demand Factors

Quick Answer: For a single domestic installation, group connected loads per AS/NZS 3000 Appendix C Table C1 (live edition), apply each row’s first/additional or percentage assessment, sum the diversified contributions, and convert to amperes. Patterns below are illustrative teaching examples — confirm every factor and breakpoint in the open-book standard on assessment day.

How to Read a Domestic Table C1 Task

Capstone and TAFE calculations almost always follow the same rhythm:

1. Confirm installation type — single domestic dwelling versus multiple domestic or non-domestic (wrong table = wrong answer).
2. List connected loads by group — lighting; socket-outlets / general-purpose outlets; cooking; water heating; air conditioning / space heating; other fixed appliances; any special loads the table isolates.
3. For each group, apply the live table’s method — percentages of connected load, “first X then remainder,” or point-based assessments where the edition uses them.
4. Respect footnotes — what counts as a “point,” whether ranges and ovens combine, how three-phase appliances are treated, and whether certain loads are assessed at 100%.
5. Sum diversified group demands → state maximum demand in A (and show V and phase assumptions).

Australian English exam answers should say general-purpose outlets (GPOs) or socket-outlets as your RTO wording prefers, consumer mains, and main switch — not US “panelboard” slang.

Illustrative Load-Group Patterns (Verify Live)

The following patterns reflect commonly taught Table C1-style reasoning for a single domestic installation. They are deliberately labelled illustrative because AS/NZS 3000 editions revise numeric breakpoints. Use them to learn structure; copy numbers from your authorised standard in the real assessment.

Lighting

Lighting is usually assessed from connected wattage (or from a points method if your edition phrases it that way). A frequently taught illustrative pattern is:

• Assess an initial portion of connected lighting load at a high factor (often 100% of the first kilowatt-scale band).
• Assess the remainder at a reduced percentage (commonly taught examples use figures such as 75% of the balance).

Why the step-down? Extra lighting circuits in a large house rarely all peak with every lamp on. Still, you must include the full connected inventory before applying the table — diversity is applied by the table, not by quietly omitting rooms.

General-purpose outlets / socket-outlet groups

Domestic GPO circuits are classic diversity candidates: many outlets, intermittent use. Illustrative teaching patterns often look like:

• Assess the first band of connected socket-outlet load (for example a first 10 A of diversified contribution, or a first count of points at a stated ampere each — match your live row).
• Assess additional outlets or additional connected load at a lower ampere-per-point or percentage rate.

Common apprentice error: treating every 10 A circuit as simultaneously drawing 10 A into the MD. Table C1-style methods exist precisely to stop that inflation while still covering realistic peaks (kettle + microwave + toaster coincidence on kitchen circuits, for example).

Cooking appliances

Ranges, ovens and cooktops are high individual loads with moderate coincidence across multiple cooking appliances. Illustrative patterns commonly:

• Take a high percentage (often 100% or similar) of the largest cooking appliance load up to a stated limit.
• Apply a reduced percentage to additional cooking appliances.

Read whether the table treats a freestanding range as one appliance and a separate oven as another. Mis-grouping cooking loads is a frequent source of MD error.

Water heating

Storage and instantaneous water heaters often attract little diversity because recovery elements can present long duty cycles. Illustrative teaching frequently assesses water heating at or near 100% of connected load for the relevant category — but instantaneous units, controlled off-peak elements, and multiple heaters may have separate rows or notes. Never apply a socket-outlet-style 40% factor to a dedicated water heater just because “diversity feels right.”

Air conditioning and fixed space heating

Comfort loads can dominate summer or winter peaks. Illustrative Table C1-style approaches often:

• Assess the largest air-conditioning or heating load at a high factor (commonly full load).
• Apply diversity to additional units where the table provides a reduced factor.

Heat-pump reverse-cycle units still need their electrical input assessed from nameplate or design data — do not confuse thermal kW with electrical kW.

Other fixed appliances

Clothes dryers, pool equipment, garage door drives and similar fixed appliances appear as their own groups or as “other fixed appliances” depending on edition wording. Typical teaching:

• Identify each appliance’s connected load.
• Apply the specific percentage or first/additional rule for that row.
• Watch for appliances already counted under another group (avoid double counting).

Instantaneous / special loads

Some editions isolate spa pools, saunas, welders or large instantaneous heaters. If the scenario includes them, find the dedicated row. Capstone markers notice when candidates shove a spa into “GPO diversity.”

Worked Domestic Example (Step-by-Step, Illustrative Factors)

Scenario (single-phase 230 V domestic dwelling — illustrative numbers for method drill):

Illustrative Table C1-style assessments used below (VERIFY LIVE — do not treat as the legal table):

• Lighting: 100% of first 1 000 W + 75% of remainder.
• Socket-outlets: already stated as diversified contribution 16 A total after table application (10 A + 6 A) for this drill.
• Cooking: 100% of largest (8 000 W) + 50% of additional (0.5 × 3 000 W) — illustrative only.
• Water heater: 100% of 3 600 W.
• Air conditioning: 100% of 2 500 W (single unit).
• Dryer: 100% of 2 400 W (illustrative full assessment for a single fixed appliance row).

Step 1 — Lighting diversified watts

• First 1 000 W × 100% = 1 000 W
• Remainder 800 W × 75% = 600 W
• Lighting MD contribution = 1 600 W

Step 2 — Socket-outlets

• Diversified contribution given by illustrative table application = 16 A
• In watts at 230 V: 16 × 230 = 3 680 W (keep A and W consistent in your working; many candidates stay in amperes once converted).

Step 3 — Cooking

• Largest: 8 000 W × 100% = 8 000 W
• Additional: 3 000 W × 50% = 1 500 W
• Cooking contribution = 9 500 W

Step 4 — Water heater = 3 600 W
Step 5 — Air conditioning = 2 500 W
Step 6 — Dryer = 2 400 W

Step 7 — Sum watt-based groups

Lighting + cooking + water + AC + dryer = 1 600 + 9 500 + 3 600 + 2 500 + 2 400 = 19 600 W
Convert: 19 600 W ÷ 230 V ≈ 85.2 A
Add socket-outlet diversified amperes: 85.2 + 16 ≈ 101.2 A

Illustrative MD ≈ 101 A (round per your RTO’s instruction — often to next practical design step when selecting switchgear, without pretending rounding replaces table accuracy).

Exam presentation tip: Tabulate each group’s connected load, factor/rule cited, diversified result, then a total. Assessors follow tidy working faster than a paragraph of mental arithmetic.

Three-Phase Domestic Notes

Some larger dwellings are three-phase. Convert loads carefully:

• Line current for balanced three-phase power uses (I = P / (\sqrt{3} \times V_{L-L})) with the correct line voltage.
• Unbalanced single-phase loads across phases need phase-by-phase thinking before stating a main-switch current.
• Table rows may still be watt-based; conversion happens after diversification.

Quality Checks Before You Box the Answer

• Did you use the domestic table, not a commercial alternative method by accident?
• Did any continuous load incorrectly receive aggressive diversity?
• Did you double-count an appliance?
• Are units consistent (W vs A vs kVA)?
• Did you write “per AS/NZS 3000 Appendix C Table C1 (edition on desk)” beside the working?

Capstone Link

Queensland capstone written items use MD to test whether you can navigate Appendix C under time pressure. Practical days may assume a calculated MD when selecting or verifying mains and main switches. Practise until the method is automatic and the numbers always come from the open book. Section 6.3 shows how that MD figure sizes commercial and mains arrangements once domestic fluency is in place.