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Maximum Demand Calculator with Examples AS/NZS 3000

Free online maximum demand calculator of electricity for Australia and New Zealand, according to AS/NZS 3000. Includes Formulas and Examples.

House, shed or individual living unit

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Contents

Parameters

  • Application: Select your application.
  • Load type: Select the load type from the drop-down menu. Each load type maps to a load group in AS/NZS 3000. The load types and groups are described in Table 1 below. You can use the same load type multiple times.
  • Red, White and Blue phase (A or x): Specify the number of loads (x) or the connected load (A) as indicated.
    • Single-phase installations: Choose one phase for all inputs, and ignore the other two phases. For example, use only the red phase.
    • Three-phase installations: Distribute single-phase loads evenly across the three phases. Single-phase motor loads must be on seperate lines. Other single-phase loads of the same type, can be entered in the same line. The values can be different per phase. Three-phase loads must have the same value in all three phases.

How to calculate maximum demand of electricity?

The maximum demand of electricity in Australia and New Zealand is calculated according to Tables C1 and C2 in AS/NZS 3000. Table C1 is for domestic applications, and Table C2 is for commercial applications.

Maximum Demand Formulas for single domestic electrical installations.

Table C1 below is based on Table C1 (column 1) in AS/NZS 3000. It shows how to calculate the maximum demand for single domestic electrical installations.

Note that the layout in Table C1 below is different from the standard, and I have re-phrased it in my own words.

I also added a few specific load types to simplify the calculator. The formulas and the calculated result is the same as the standard.

Table C1: Maximum Demand Formulas for Single Domestic Electrical installations.
Load Group Description
ai) Lighting, general Input: Number of light points per phase.
Formula:
  • 3 A for first 20 points.
  • Plus 2 A for each additional 20 points, or any part of it.
Include dedicated lighting socket outlets higher than 2.3 m.
Lighting track = 2 points/m.
aii) Lighting, outdoor > 1000W Input: Connected load in A per phase.
Formula: 75% connected load
Lighting track = 0.5 A/m.
bi) Socket-outlet, general use ≤ 10A Input: Number of sockets per phase.
Formula:
  • 10 A for first 20 points.
  • Plus 5 A for each additional 20 points, or any part of it.
bii) Socket-outlet, general use ≤ 15A Input: Number of sockets per phase.
Formula:
  • 10 A for 1 or more sockets.
  • If there is a 20 A socket in the same phase, 15 A is used for both.
Exclude socket-connected cooking and laundry equipment > 10 A.
biii) Socket-outlet, general use ≤ 20A Input: Number of sockets per phase.
Formula:
  • 15 A for 1 or more sockets.
  • If there is a 15 A socket in the same phase, 15 A is used for both.
Exclude socket-connected cooking and laundry equipment > 10 A.
c) Cooking, range > 10A
c) Cooking, other > 10A		 Input: Connected load in A per phase.
Formula: 50% connected load.
Include socket connected equipment here.
A range is typically a stove with hotplates on top.
It does not matter what you call it.
If it is used for cooking, and its > 10A, use this load group.
c) Laundry, appliance > 10A
 Input: Connected load in A per phase.
Formula: 50% connected load.
Include socket connected equipment here.
Washing machine or dryer.
d) HVAC, Airconditioning > 10A
d) HVAC, Heating > 10A
 Input: Connected load in A per phase.
Formula: 75% connected load.
General Air conditioning, Space heating, and Sauna heating.
Include socket connected equipment here.
e) Water heater, instantaneous Input: Connected load in A per phase.
Formula: 33.3% connected load.
Include quick recovery heaters when element rating > 100 W/litre.
f) Water heater, storage Input: Connected load in A per phase.
Formula: 100% connected load.
Include quick recovery heaters when element rating ≤ 100 W/litre.
g) Water heater, pool or spa Input: Connected load in A per phase.
Formula:
  • Largest swimming pool, 75% connected load.
  • Largest spa, 75% connected load.
  • Remaining water heaters, 25% connected load.
Swimming pool or spa heater.
This calculator supports only one swimming pool heater and one spa heater.
If you need to use more, you can include them under "m) Other, appliances > 5A", and apply the diversity yourself.
jiv) Charging, electric vehicle Input: Connected load in A per phase.
Formula: 100% connected load
k) Motor, lift Input: Connected load in A per phase.
Formula:
  • Largest lift motor, 125% connected load.
  • Next largest lift motor, 75% connected load.
  • Remaining lift motors, 50% connected load.
Connected load current means when lifting maximum rated load at rated maximum speed.
This calculator supports only one lift motor.
If you need to use more, you can include them under "m) Other, appliances > 5A", and apply the diversity yourself.
l) Motor, general
 Input: Connected load in A per phase.
Formula:
  • Largest motor, 100% connected load.
  • Remaining motors, 50% connected load.
Include socket connected motors.
Include pool pump motors.
Exclude lift motors.
m) Other, appliances > 5A Input: Connected load in A per phase.
Formula: Self-assess the maximum demand. Worse-case, use the connected load.
Examples: Pottery kiln, welding machine, radio transmitter, etc.
Permanently connected appliances > 5A.
Ignore if the load is ≤ 5A.

Maximum demand examples for single domestic installations.

Example 1: Single-phase, house, 3 bedroom, 1 bathroom, 1 carport.

  • 25 General lighting points. Including outdoor lights.
  • 22 Socket outlets (10A ), i.e. 11 double socket arrangements.
  • 1 Cooking range (Stove), 6.9 kW at 230 V.
  • 1 Ducted air conditioner. 10 kW cooling and 11.2 kW heating. Maximum current 20A.

Input values

Load group Red phase
ai) Lighting, general 25 points
bi) Socket-outlet, general use ≤ 10A 22 points
c) Cooking Range (Stove) > 10A 30 A
d) HVAC, Airconditioning > 10A 20 A

The current for the air conditioner is from the manufacturer's specification. It is not calculated from the cooling or heating kilowatt rating, because a reverse cycle air conditioner uses less electricity relative to the cooling or heating power.

Laundry equipment is not listed separately. They are included in "bi) Socket-outlet, general use ≤ 10A", because they are < 10A.

After diversity maximum demand

Load group Red phase
ai) Lighting, general
3A + 2A		 5 A
bi) Socket-outlet, general use ≤ 10A
10A + 5A		 15 A
c) Cooking Range (Stove) > 10A
30A × 0.5		 15 A
d) HVAC, Airconditioning > 10A
20A × 0.75		 15 A
Total 50 A

Example 2: Single-phase, club-house with tennis court.

  • 24 General lighting points. Excluding tennis court lights.
  • 10 Meter lighting track.
  • 9 Single socket outlets (10A).
  • 8 Double socket outlets (10A).
  • 1 Single socket outlet (15A)
  • 1 50 W exhaust fan.
  • 1 1000 W strip heater.
  • 1 Cooking range (Stove), 10 kW at 230 V.
  • 1 Water heater, 4.8 kW at 230 V.
  • 1 Tennis court lighting, 3kW

Input values

Load group Red phase
ai) Lighting, general 45 points
aii) Lighting, outdoor > 1000W 13 A
bi) Socket-outlet, general use ≤ 10A 25 points
bii) Socket-outlet, general use ≤ 15A 1 point
c) Cooking Range (Stove) > 10A 43.5 A
f) Water heater, storage 20.9 A

Lighting track is included as 2 lighting points per meter.

The exhaust fan is included as a lighting point, because it is < 60 W and it is switched on and off with a light switch.

After diversity maximum demand

Load group Red phase
ai) Lighting, general
3A + 2A + 2A		 7 A
aii) Lighting, outdoor > 1000W
13A × 0.75		 9.8 A
bi) Socket-outlet, general use ≤ 10A
10A + 5A		 15 A
bii) Socket-outlet, general use ≤ 15A 10 A
c) Cooking Range (Stove) > 10A
43.5 × 0.5		 21.8 A
f) Water heater, storage
20.9A × 1.0		 20.9 A
Total 85 A

Example 3: Three-phase, house

  • 25 General lighting points.
  • 20 Double socket outlets (10A).
  • 2 Single socket outlet (15A)
  • 1 15 kW 3-phase range. With 7 kW oven, and two 4 kW hotplates.
  • 1 7.5 kW Single-phase split unit air conditioner, with a maximum current of 15 A.
  • 1 12 kW 3-phase instantaneous water heater.
  • 1 3.8 kW single-phase laundry dryer connected to its own dedicated 20 A socket.

Input values

Load group Red phase White phase Blue phase
ai) Lighting, general 25 points
bi) Socket-outlet, general use ≤ 10A 10 points 10 points
bii) Socket-outlet, general use ≤ 15A 2 points
c) Cooking Range (Stove) > 10A 30.4A
c) Cooking, other > 10A 17.4A 17.4A
c) Laundry, dryer > 10A 16.5A
d) HVAC, Airconditioning > 10A 15A
e) Water heater, instantaneous 17.4A 17.4A 17.4A

After diversity maximum demand

Load group Red phase (A) White phase (A) Blue phase (A)
ai) Lighting, general
Red: 3A + 2A		 5
bi) Socket-outlet, general use ≤ 10A
Red: 10A
White: 10A		 10 10
bii) Socket-outlet, general use ≤ 15A
Blue: 10A		 10
c) Cooking Range (Stove) > 10A
Red: 30.4A × 0.5		 15.2
c) Cooking, other > 10A
White: 17.4A × 0.5
Blue: 17.4A × 0.5		 8.7 8.7
c) Laundry, dryer > 10A
Blue: 16.5A × 0.5		 8.3
d) HVAC, Airconditioning > 10A
White: 15A × 0.75		 11.3
e) Water heater, instantaneous
Red: 17.4A × 0.33
White: 17.4A × 0.33
Blue: 17.4A × 0.33		 5.8 5.8 5.8
Total 36 A 36 A 33 A