ELECTRICAL INSTALLATION PLANNING. LSEGG307A 9080F. 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. MD.
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What is Maximum Demand?
Is the “Maximum continuous current that flows in a circuit for a period of 15 minutes or longer”
AS/NZS 3000
1.6.3
Why not just put a cable size in, that will handle the current rating for the maximum current rating of the appliance?
Domestic stove rated at 5kW
Max current = 22A
Min cable size = 6mm2
By calculation
AS/NZS 3000
Table C4
Max current = 16A
Min cable size = 2.5mm2
Calculation
Assessment
Measurement
Limitation
AS/NZS 3000
2.2.2.
“If the measured current is larger than any of the listed methods, then the MD is considered the measured value”
“… may be the ….sum of the current settings of the circuit breakers protecting the associated final subcircuits….”
AS/NZS 3000
Clause 2.2.2 (d)
10+10+16+16+32 =
By Calculation
16mm2
84 Amps
36 Amps
MD = ?
Most supply authorities specify a minimum mains cable size of 16 mm2
2.5mm2
10mm2
20 metres
46 metres
10A
L1
10A
L2
16A
P1
16A
P2
32A
Stove
Domestic House
Table C1
Column 2
Lighting
Load groups Ai & Aii
Batten holder =
1 light point
25 lighting points =
1 20 =
3 A
21 25 =
2 A
5 A
Single House
Table C1
Column 2
Lighting
Load groups Ai & Aii
Chandelier or Multiglobe fitting =
Number of points =
Number of globes
= 3 points
Single House
Table C1
Column 2
Lighting
Load groups Ai & Aii
Power points above 2.3 m for lighting =
1 point
Note “e”
Exhaust fans below 150W =
1 point
Single House
Table C1
Column 2
Lighting
Load groups Ai & Aii
Track lights =
Every metre =
2 points
Note “d”
2 x 2.6 metres track light =
5 points per track =
10 points
Single House
Table C1
Column 2
Lighting
Load groups Ai & Aii
IXL Tastics, Heat lamps etc
Not regarded as “Lighting”
Fixed Space Heating
Load Group “D”
Single House
Table C1
Column 2
Lighting
Load groups Ai & Aii
Outside Lighting
Floodlighting, Swimming Pool, Tennis courts, etc
Not lighting around house walls
If total bigger than 1000W
If less than 1000W
Load Group “Aii”
Single House
Load Group “Ai”
A house consists of the following:
Assume to be <150W
36 light fittings, 3 consisting of 3 lamp combinations
3 bathroom exhaust fans
2 x 750W heat lamp, fan, light combinations
3 x 2metre track lights
12 wall lights around the veranda
6 x 100W bollard lights on driveway
6 x 400W metal halide flood lights for pool
Ai
Ai
D
Ai
Ai
Aii
Aii
33 + (3 x 3) = 42P
3P

3 x 2 x 2 = 12P
12P
13.04A
6 x 100 =
600
3000 W
6 x 400 =
2400
230V
Determine the lighting load in Amps
A house consists of the following:
36 light fittings, 3 consisting of 3 lamp combinations
3 bathroom exhaust fans
2 x 750W heat lamp, fan, light combinations
3 x 2metre track lights
12 wall lights around the veranda
6 x 100W bollard lights on driveway
6 x 400W metal halide flood lights for pool
Ai
Ai
D
Ai
Ai
Aii
Aii
33 + (3 x 3) = 42P
3P

3 x 2 x 2 = 12P
12P
13.04A
42P
3P
12P
12P
1 – 20 =
21 – 40 =
41 – 60 =
61 – 69 =
3A
2A
2A
2A
22.04A
69P
9A
+ 13.04A =
Broken up evenly
ABC
36 light fittings
12 Fittings /
3A
3A
3A
3
Should indicate how it is to be broken up across the three phases
NOT
ABC
36 light fittings
= 3A + 2A = 5A
1.6
1.6
1.6
3
A house consists of the following:
Broken up evenly over 3 Phases
36 light fittings, 3 consisting of 3 lamp combinations
3 bathroom exhaust fans
2 x 750W heat lamp, fan, light combinations
3 x 2metre track lights
12 wall lights around the veranda
6 x 100W bollard lights on driveway
6 x 400W metal halide flood lights for pool
Ai
Ai
D
Ai
Ai
Aii
Aii
11 + (1 x 3) = 14P
1P

1 x 2 x 2 = 4P
4P
4.35A
Divide by 3
14P
1P
4P
4P
1 – 20 =
21 – 23 =
3A
2A
9.35A /
23P
5A
+ 4.35A =
Notes
h
Double Power Points
Load Group Bi36 Double Power Points
6 Single power points
36 x 2 =72P
6P
1 – 20 =
21 – 40=
41 – 60 =
61 – 78 =
10A
5A
5A
5A
78P
25A
Notes
h
Double Power Points
Load Group Bi36 Double Power Points
6 Single power points
36 x 2 =72P
6P
1 – 20 =
21 – 40=
41 – 60 =
61 – 78 =
10A
5A
5A
5A
AND
78P
Other Direct Wired Equipment that is <10A
25A
NOT
15 A Power Points
Other Equipment that is Covered in Load Groups below
Load Group BiiC Ranges, Laundry equipment
D Fixed Space Heating or cooling equipment
E & F Water Heaters
G Spa & Swimming Pool Heaters
15 A Power Points suppling this equipment is covered under each load group
A house consists of the following:
20 Double power points
8 Single power points
8A swimming pool pump
4 x 15A power points
12A Airconditioner supplied via a 15A power point
14A Pool heater direct wired
Bi
Bi
Bi
Bii
D
G
20 x 2 = 40P
8P
1P
10A


3
Determine the Power point load in Amps
A house consists of the following:
20 Double power points
8 Single power points
8A swimming pool pump
3 x 15A power points
12A Airconditioner supplied via a 15A power point
14A Pool heater direct wired
Bi
Bi
Bi
Bii
D
G
20 x 2 = 40P
8P
1P
10A


40P
8P
1P
1 – 20 =
21 – 40 =
41 – 49 =
10A
5A
5A
30A
49P
20A
+ 10A =
Must be over 10A
If supplied via a power point
That power point is NOT included in Bi, Bii or Biii
50% of connected Load
An installation has:
2.3 kW Cook top
4 kW Wall oven
6.3 kW of Load Group C
(6300/230)
x 0.5 =
13.7A
Must be over 10A
If supplied via a power point
That power point is NOT included in Bi, Bii or Biii
75% of connected Load
If reverse cycle Airconditioner is used only the highest system is to be taken into account
Unless it is multi zone, when both heating and cooling could operate simultaneously
Water Heaters
Load Group E
15 litre heater
with a 2.4kW element
33.3% of connected load
2400/15 =
160 W/L
If greater than 100W/L
Load Group F
300 litre heater
with a 2.4kW element
100% of connected load
2400/300 =
8 W/L
A house consists of the following:
Ai
Ai
Bi
Bi
C
D
F
41 x 50 W down lights
2 x 60 W exhaust fans
4 x Single 10 A socket outlets
22 x Double 10 A socket outlets
1 x 10kW range
1 x Permanently connected air conditioner (full load current of 13 A)
1 x 4.6 kW continuous HWS
A house consists of the following:
Ai
Ai
Bi
Bi
C
D
F
41 x 50 W down lights
2 x 60 W exhaust fans
4 x Single 10 A socket outlets
22 x Double 10 A socket outlets
1 x 10kW range
1 x Permanently connected air conditioner (full load current of 13 A)
1 x 4.6 kW continuous HWS
43P
3 + 2 + 2 =
7A
A house consists of the following:
Ai
Ai
Bi
Bi
C
D
F
41 x 50 W down lights
2 x 60 W exhaust fans
4 x Single 10 A socket outlets
22 x Double 10 A socket outlets
1 x 10kW range
1 x Permanently connected air conditioner (full load current of 13 A)
1 x 4.6 kW continuous HWS
7A
44 + 4 = 48P
10 + 5 + 5 =
20A
44P
A house consists of the following:
Ai
Ai
Bi
Bi
C
D
F
41 x 50 W down lights
2 x 60 W exhaust fans
4 x Single 10 A socket outlets
22 x Double 10 A socket outlets
1 x 10kW range
1 x Permanently connected air conditioner (full load current of 13 A)
1 x 4.6 kW continuous HWS
7A
20A
(10000/230) x 0.5 =
21.7A
A house consists of the following:
Ai
Ai
Bi
Bi
C
D
F
41 x 50 W down lights
2 x 60 W exhaust fans
4 x Single 10 A socket outlets
22 x Double 10 A socket outlets
1 x 10kW range
1 x Permanently connected air conditioner (full load current of 13 A)
1 x 4.6 kW continuous HWS
7A
20A
21.7A
9.75A
13 x 0.75 =
A house consists of the following:
Ai
Ai
Bi
Bi
C
D
F
41 x 50 W down lights
2 x 60 W exhaust fans
4 x Single 10 A socket outlets
22 x Double 10 A socket outlets
1 x 10kW range
1 x Permanently connected air conditioner (full load current of 13 A)
1 x 4.6 kW continuous HWS
7A
20A
21.7A
9.75A
4600/230 =
20A
A house consists of the following:
Ai
Ai
Bi
Bi
C
D
F
41 x 50 W down lights
2 x 60 W exhaust fans
4 x Single 10 A socket outlets
22 x Double 10 A socket outlets
1 x 10kW range
1 x Permanently connected air conditioner (full load current of 13 A)
1 x 4.6 kW continuous HWS
7A
20A
21.7A
9.75A
20A
78.45A
Not all single phase loads will break up evenly over three phases
But the phases must not be unbalanced by more than 25A
NSW S&IR
Clause 1.10.3
A house consists of the following:
Ai
Ai
Bi
Bi
C
C
F
D
A
30 x Light points + 2 x Exhaust fans
18 x Lights
6 x 400W mercury vapour flood lights
15 x Double power points (p/p)
3 x 15ASingle p/p
1 x 4.1kW wall oven
1 x 4.6kW cook top
A house consists of the following:
Ai
Ai
Bi
Bi
C
C
F
D
A
30 x Light points + 2 x Exhaust fans
18 x Lights
6 x 400W mercury vapour flood lights
15 x Double power points (p/p)
3 x 15ASingle p/p
1 x 4.1kW wall oven
1 x 4.6kW cook top
32P
3+2A =
5A
15A
8.91A
6.17A
3A
20A
10A
6.17A
18P
7.83A
10A
15.65A
6.17A
((6x400)230)x0.75=
30P
10+5A =
10+30P
10+5A =
(4100230)x0.5=
(4600230)x0.5=
3600230=
(5700x0.75)(√3 x400)=
35.1A
39.2A
40.2A
6 Units
= 2 Units / Phase
Use Colum
3
3
18 Units
= 6 Units / Phase
Use Colum
4
3
66 Units
= 22 Units / Phase
Use Colum
5
3
A house consists of the following:
Ai
Ai
Bi
Bi
C
D
F
26 x Light points
2 metres of light track
2 x 750W flood lights
26 x Double 10 A socket outlets
1 x 15ASingle socket outlet
1 x 5.6kW wall oven / cook top
1 x 3.6kW air conditioner
1 x 2.4kW storage HWS (Heat pump)
26 + 4 = 30P
3A + 2A =
5A
4.9A
20A
10A
12.2A
11.7A
10.4A
2 x 2 = 4P
1500W
(1500W/230V)x0.75
10A + 5A + 5A =
26 x 2 = 52P
52 + 5 = 57P
(5600W/230V)x0.5
(3600W/230V)x0.75
(2400W/230V)
74.2A
9 Units consists of the following:
9 Units
= 3 Units / Phase
Use Colum
3
3
Ai
Ai
Bi
Bi
C
D
F
26 x Light points
2 metres of light track
2 x 750W flood lights
26 x Double 10 A socket outlets
1 x 15ASingle socket outlet
1 x 5.6kW wall oven / cook top
1 x 3.6kW air conditioner
1 x 2.4kW storage HWS (Heat pump)
6A
25A
10A
15A
35.2A
18A
Not counted
10A + (5A x 3) =
(3600W/230V) x 0.75 x 3
6A x 3 =
109A
30 Units consists of the following:
30 Units
= 10 Units / Phase
Use Colum
4
3
Ai
Ai
Bi
Bi
C
D
F
26 x Light points
2 metres of light track
2 x 750W flood lights
26 x Double 10 A socket outlets
1 x 15ASingle socket outlet
1 x 5.6kW wall oven / cook top
1 x 3.6kW air conditioner
1 x 2.4kW storage HWS (Heat pump)
7.5A
52.5A
10A
28A
117A
60A
5A + (0.25A x 10) =
Not counted
15A + (3.75A x 10) =
2.8A x 10 =
(3600W/230V) x 0.75 x 10
6A x 10 =
275A
66 Units consists of the following:
66 Units
= 22 Units / Phase
Use Colum
5
3
Ai
Ai
Bi
Bi
C
D
F
26 x Light points
2 metres of light track
2 x 750W flood lights
26 x Double 10 A socket outlets
1 x 15ASingle socket outlet
1 x 5.6kW wall oven / cook top
1 x 3.6kW air conditioner
1 x 2.4kW storage HWS (Heat pump)
11A
91.8A
10A
61.6A
258A
118A
0.5A x 22 =
Not counted
50A + (1.9A x 22) =
2.8A x 22 =
(3600W/230V) x 0.75 x 22
100A + (0.8A x 22) =
550A
16 Units
= 5.33 Units / Phase
3
A
B
C
5 Units
5 Units
6 Units
Col 3
Col 3
Col 4
But the phases must not be unbalanced by more than 25A
NSW S&IR
Clause 1.10.3
16 Units consists of the following:
5Units / A & B
Use Colum
3
Ai
Bi
Bi
C
D
F
26 x Light points
26 x Double 10 A socket outlets
1 x 15ASingle socket outlet
1 x 5.6kW wall oven / cook top
1 x 3.6kW air conditioner
1 x 2.4kW storage HWS (Heat pump)
6A
35A
10A
15A
58.7A
52.2A
10A + (5A x 5) =
(3600W/230V) x 0.75 x 5
(2400230V) x 5 =
176.9A
16 Units consists of the following:
6Units / C
Use Colum
4
Ai
Bi
Bi
C
D
F
26 x Light points
26 x Double 10 A socket outlets
1 x 15ASingle socket outlet
1 x 5.6kW wall oven / cook top
1 x 3.6kW air conditioner
1 x 2.4kW storage HWS (Heat pump)
5A + (0.25A x 6) =
6.5A
37.5A
10A
16.8A
70.4A
36A
15A + (3.75A x 6) =
2.8A x 6=
(3600230) x 0.75 x 6
6A x 6 =
177.2A
16 Units
= 5.33 Units / Phase
3
A
B
C
5 Units
5 Units
6 Units
Col 3
Col 3
Col 4
176.6A
176.6A
177.2A
Loads that are used by all the unit dwellers
16 Units have a communal load consists of the following:
H
H
I
Jii
D
E
20 x 80 W bollard Lights
30 x light points
1 x 3.6kW HWS for cleaners room
1 x 3.6kW Air conditioner for lobby
1 x 12A pool pump/filter
1 x 15A lift motor
((20x80)230) + ((30x 60)230)=
14.78A
15A
7.8A
15A
12A
18.75A
2A x15= 30 but maximum of 15A
(3600230) x 0.5 =
(3600230) x 0.75 =
15 x 1.25 =
Table C2 Colum 2
83.33A
These circuits could also be divided across three phases
In a Factory
On each Phase
1000W +
19 x 750W =
15.25kW
15250 ÷ 230 =
66.3 Amps
In areas with air conditioning
1000W +
19 x 100W =
2.9kW
2900 ÷ 230 =
12.6 Amps
Treat as B(i)
1000W + 4 x 750W =
4kW
Per Phase
17.4 Amps
4000 ÷ 230 =
Per Phase
75% x 32A
75% x 20A x 5
131Amps
32A +
24A +
75A =
In Factories
1 per phase
75% x 30A
50% x 3 x 15A
30A +
22.5A +
22.5A =
75 Amps
AS/NZS 3000
C2.5.2.2 (b)
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
Table based on a temperate climate
Office
Floor area =
Light/Power =
Reverse cycle AC =
850m2
50 VA/m2
25 VA/m2
x 850 =
63.750kVA
75 VA/m2
63.750kVA
92 Amps/Phase
=
√3 x 400
Use for a ‘Ball Park’ figure in early planning stages.