1. ELECTRICAL INSTALLATION PLANNING
LSEGG307A
9080F

2. Lesson Content
Describe the acceptable methods for determining the maximum demand on an installation’s consumer’s mains.
Calculate the maximum demand for the consumer's mains for given installations up to 400 A per phase.

3. Maximum Demand Non-Domestic
Load are generally heavier
Stay on for longer periods of time
Heating & cooling has an effect on load

4. Residential Instillations
Hotels
Boarding Houses
Hospitals
Motels
etc
AS/NZS 3000
Table C2
Colum 2

5. Residential Instillations
Lighting
AS/NZS 3000
Table C2
Colum 2
Load group A
75% connected load
Note B
Incandescent Lamps = 60W
Unless the fitting restricts the wattage to less
Track lights = 0.5A/m

6. Residential Installations
10A Power Points
Load group B
If this section of building
DOES NOT HAVE
fixed heating/cooling
Load Group Bi
20 Double power points
72.2A
20 x 2 = 40 Points
1000W + (39 x 400W) =
16600230 =
First Point
Balance

7. Residential Installations
10A Power Points
Load group B
If this section of building
DOES NOT HAVE
fixed heating/cooling
HAS
Load Group Bii
Load Group Bi
20 Double power points
21.3A
72.2A
20 x 2 = 40 Points
1000W + (39 x 100W) =
1000W + (39 x 400W) =
16600230 =
4900230 =
First Point
Balance

8. Residential Installations
Power Points
Larger than 10A
Load group Biii
1st = full current of highest
2nd = 50% x full current
3rd = 50% x full current
2 x 20A power points
2 x 15A power points
20A
0.5 x 20 = 10A
0.5 x 15A = 7.5A
45A

9. Residential Installations
Power Points
3 Outlets
Load Group B
10A 3 Outlet A B C
1 Point
1 Point
1 Point

10. An air conditioned motel consists of the following:
Exercise 1
An air conditioned motel consists of the following: A
Bii
Biii A B C
30 x Light points
40 x Lights
6 x 400W mercury vapour flood lights
15 x Double power points (p/p)
10 x Single p/p & 15 x Double p/p
3 x 15A Single p/p
1 x 10A 3 outlet
((30x60)230)x0.75 =
5.87A
17.4A
((40x60)230)x0.75 =
7.83A
21.7A
((6x400)230)x0.75 =
7.83A
34.3A
31P
(1000+(30x100))230 =
11+30P
(1000+(40x100))230 =
(1000230)+15+((2x15)x0.5) =
23.3A
29.5A
42.1A
NSW S&IR
Clause
Less than 25A difference

11. Factories
Shops
Offices
Schools
Churches
AS/NZS 3000
Table C2
Colum 3

12. Factories Lighting Note B AS/NZS 3000 Table C2 Colum 3 Load group A
100% connected load
Note B
Incandescent Lamps = 60W
Unless the fitting restricts the wattage to less
Track lights = 0.5A/m

13. Factories 10A Power Points Load Group Bi AS/NZS 3000 2.2.2.
Calculation
Assessment
Measurement
Limitation
Load group B
If this section of building
DOES NOT HAVE
fixed heating/cooling
Load Group Bi
20 Double power points
131.5A
20 x 2 = 40 Points
1000W + (39 x 750W) =
30250230 =
First Point
Balance

14. Factories 10A Power Points Load Group Bii Load Group Bi Load group B
If this section of building
DOES NOT HAVE
fixed heating/cooling
HAS
Load Group Bii
Load Group Bi
20 Double power points
21.3A
131.5A
20 x 2 = 40 Points
1000W + (39 x 100W) =
1000W + (39 x 750W) =
30250230 =
4900230 =
First Point
Balance

15. Factories Power Points Larger than 10A Load group Biii
1st = full current of highest
2nd = 75% x full current
3rd = 75% x full current
2 x 20A power points
2 x 15A power points
20A
0.75 x 20 = 15A
0.75 x 15A = 11.25A
57.5A

16. Only 2 welders on each phase
AS/NZS 3000
C (b)
3 x 20A 3 Welders
Majority of welders only use 2 phases B A C
Only 2 welders on each phase
W 1
W 2
W 3
20A + 20A =
40 Amps
Per Phase

17. C3 Commercial & Light industrial
Used to give a “Ball Park” figure of maximum demand when actual loads are not available in the initial design stages
Values are given in VA per m2 of floor area

18. C3 Commercial & Light industrial
10 metre x 10 metre air conditioned shop
10 x 10 =
100 m2
From C3
Light & power (average value)=
70 VA/m2
Air conditioning=
30 VA/m2
100 VA/m2
100 m2 x
100 VA/m2 =
10kVA =
14.4A /
400 x √3

19. Maximum Demand Final Sub-circuits Single items on circuit
Multiple items on circuit
Diversity may be applied
Current rating of appliance
Limit by circuit breaker
Welders
Domestic cooking appliances

20. Welding Machines Types Arc Welding Machines Stick MIG TIG Highest
1st Machine
2nd
3rd
4th
5th + more
100%
85%
70%
60%
Lowest
Rated Primary Current
Actual Primary Current

21. Welding Machines Types Arc Welding Machines Stick MIG TIG
Resistance Welding Machines
Stick
MIG
TIG
Spot welders
Rated Primary Current
Actual Primary current
Duty Cycle

22. Resistance Welding Machines
Individual Machines
Variable Operation
Specific (fixed) Operation
Seam welders
Auto feed welders
Manual welders
Non-Auto Welders
70%
50%
x Rated Primary Current
Actual Primary current x Multiplier

23. Duty Cycle Ratio of ON TIME/OFF TIME in 1 minute 30/30 =
Very few welders operate at 100% all of the time
Changing the electrodes
Repositioning the job
Starting a new job
Ratio of ON TIME/OFF TIME in 1 minute
Weld for 30 seconds
Off for 30 seconds
30/30 =
50% Duty Cycle

24. Resistance Welding Machines
Individual Machines
Groups of machines
Variable Operation
Specific (fixed) Operation
Seam welders
Auto feed welders
Manual welders
Non-Auto Welders
70%
50%
x Rated Primary Current
Actual Primary current x Multiplier
Highest
1st Machine
2nd + More
100%
60%
Lowest

25. Domestic Cooking Appliances
Table C4
4.8kW wall oven =
6.8kW wall oven =
9kW wall oven + 4.8kW hotplate =
16A
20A
13.8kW =
40A

26. NEXT LESSON
TEST