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C5.2 Calculation of maximum demand in non-domestic electrical installations (Paragraph 4 and Table C2)

C5.2 Calculation of maximum demand in non-domestic electrical installations (Paragraph 4 and Table C2)

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256

AS/NZS 3000:2000

The load is arranged for connection across the three phase supply as
follows:
Red
White
Blue
70 lights
70 lights
60 lights
10 exhaust fans
10 exhaust fans
10 exhaust fans
5 × 10 A
5 × 10 A
socket-outlets B(i)
socket-outlets B(i)
30 ×10 A
30 × 10 A
30 × 10 A
socket-outlets B(ii)
socket-outlets B(ii)
socket-outlets B(ii)
1
× 15 A socket-outlet
1 × 15 A socket-outlet
2 × 15 A socket-outlets
5 kW hotplates
6.6 kW oven
5 kW hotplates
0.75 kW pump
0.75 kW pump
0.75 kW pump
6 kW sauna
Solution
The method of determining the demand in the heaviest loaded phase in
accordance with Table C2, Column 2 is as follows:
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Equipment
70 light points

Group
A

Calculation
70 x 60 W
× 0.75
240

60 light points

A

10 exhaust
fans

A
10 x 50 W
× 0.75
Foot240
note c

5 × 10 A
socket-outlets

B(i)

30 × 10 A
socket-outlets

B(ii)

1 × 15 A
socket-outlet
2 × 15 A
socket-outlets
6.6 kW oven
5 kW hotplate
0.75 kW
sewer pump
6 kW sauna
heater

B(iii)

2600 W
240
3900 W
1000 + (29 × 100 W ) =
240
Full current rating

B(iii)

15 A + (15 A × 0.5)

C
C
D

G

Red White Blue
A
A
A
13.13 13.13
11.25

60 x 60 W
× 0.75
240

1000 + ( 4 × 400 W ) =

1.56

1.56

1.56

10.83 10.83
16.25 16.25 16.25
15.0

15.0
22.5

27.50
2.0

20.83 20.83
2.0
2.0
25.0

86.27 87.10 91.89

257

AS/NZS 3000:2000

Example 5

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Determine the maximum demand of the heaviest loaded phase of a factory
electrical installation supplied by three-phase with the following load:
30

Twin 40 W power factor corrected fluorescent fittings

10

10 A 1-phase single socket-outlets (non-permanently heated or cooled
area)

4

10 A 1-phase double socket-outlets (permanently heated or cooled
area)

1

20 A 1-phase socket-outlet

1

15 A 1-phase socket-outlet

1

4 kW 1-phase air conditioner

1

5.5 kW 3-phase rolling machine motor

1

4 kW 3-phase lathe motor

1

3.6 kW 1-phase storage water heater

2

250 A output 3-phase arc welders (permanently connected)

1

30 kVA 2-phase spot welder
operation (Clause C4.4.3(a)(i))

1

15 kVA 2-phase spot welder (permanently connected) — specific
operation (Clause C4.4.3(a)(ii))

(permanently

connected) — varying

The load is arranged for connection across the three-phase supply as
follows:
Red

White

Blue
15 lights
5 × 10 A
socket-outlets B(i)

15 lights
5 × 10 A
socket-outlets B(i)
4 x 10 A double
socket-outlets B(ii)
3.6 kW water heater
15 A socket-outlet

20 A socket-outlet

4 kW air conditioner
5.5 kW rolling machine 5.5 kW rolling machine 5.5 kW rolling machine
4 kW lathe
4 kW lathe
4 kW lathe
250 A arc welder
250 A arc welder
250 A arc welder
250 A arc welder
250 A arc welder
250 A arc welder
30 kVA spot welder
30 kVA spot welder
15 kVA spot welder
15 kVA spot welder

258

AS/NZS 3000:2000

Solution
The method of determining the demand in the heaviest loaded phase in
accordance with Table C2, Column 3 is as follows:
Equipment

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Lighting

Calculation
Group
A
15 × 0.46 A

Red White Blue
A
A
A
6.9
6.9

10 A
socket-outlets

B(i)

1000 + ( 4 × 750 W ) =

4000 W
240

10 A
socket-outlets
(double)

B(ii)

1000 + (7 × 100 W ) =

1700 W
240

20 A
socket-outlet

B(iii) Full current rating

15 A
socket-outlet

B(iii) Full current rating

4 kW
air-conditioner

C

5.5 kW
rolling machine

D

4 kW lathe

D

rating) 0.75 × 8.3

3.6 kW
water heater

G

H

100% of rated primary
current each
(nameplate rating) —
Paragraph C4.4.2(b)(i)

250 A output
arc welder
250 A output
arc welder
30 kVA spot
welder (varying
operation,
Paragraph
C4.4.3(a)(i))

H

Manually operated, nonautomatic — 50% of the
rated primary current
(nameplate rating).
0.5 × 50 = 25 A
Groups:
Paragraph C4.4.3(b)
Largest machine: full value
obtained from Paragraph
C4.4.3(a)(i)

16.7

16.7
7.1

20.0
15.0
16.7
10.4
6.2

10.4 10.4
6.2

6.2

15.0

10.0

10.0 10.0

10.0

10.0 10.0
25.0 25.0

259

15 kVA spot
welder
(Duty cycle 20%
Paragraph
C4.4.3(a)(ii))

H

Multiplier for 20% duty cycle
is 0.45 × actual primary
current for duty cycle
selected (nameplate)
0.45 × 25 = 11.25 A
Groups:
Paragraph C4.4.3(b)
Other machines:
60% of value obtained from
Paragraph C4.4.3(a)(ii)
i.e. 0.6 × 11.25 =

AS/NZS 3000:2000

6.8
97.0

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6.8
95.5 101.9

AS/NZS 3000:2000

260

APPENDIX D

AERIAL LINES DATA
(Informative)
D1 SCOPE
The tables in this Appendix may be used as guidance when determining the
minimum size of poles or posts for aerial conductors.
NOTES:
1 A pole or post is not considered to be a structure for the purpose of the
footnotes in Tables D2 to D9 referring to ‘struts or extensions to structures’.
2 See Paragraph D2 for an example of the applications of the tables in this
Appendix.

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D2 EXAMPLE OF DETERMINATION
CONDUCTOR CLEARANCES

OF

POLE

HEIGHTS

AND

Example Determine the pole height for a 50 m span of three 10 mm2
conductors that cross an area used by vehicles.
Solution Determination of the pole height is as follows:
(a)

The type of aerial cable suitable for a 50 m span is selected from
2
Table 3.9: say three 10 mm insulated hard-drawn copper conductors,
i.e. Type A to Table D1.

(b)

The vertical clearance for this type of cable is selected from Table 3.8:
4.5 m for insulated live conductors over areas used by vehicles.

(c)

The ‘additional vertical clearance margin when stringing’ of Table D1
is selected: 0.62 m for a 50 m span.

(d)

The ‘maximum stringing conductor sag’ of Table D1 is selected: 2.0 m
for Type A conductors with a 50 m span.

(e)

The quantities 4.5 m, 0.62 m and 2.0 m as determined in Items (b), (c)
and (d) are added to obtain the minimum height of the conductor
attachment after the addition or subtraction of any allowances for
humps or hollows in the ground between the poles; with no such
allowances a total of 7.12 m is obtained.

(f)

The ‘depth in ground’ in Tables D2 to D9 of 1.6 m is selected.

(g)

The length of poles is then obtained by adding the quantities of
7.12 m, 1.6 m and allowances for the conductor height below the top
of the pole, say 0.15 m, together with any variation in depth required to
comply with Clause 3.12.6. Assuming no allowance for extra depth, a
pole length of 8.87 m is obtained as the minimum necessary for the
prevailing conditions.

A1

A1

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TABLE D1
STRINGING DATA FOR AERIAL LINES
1
Span length up to

Maximum
stringing
conductor sag b
m
0.6
0.6
1.0
1.3
2.0
2.0

3

4

5

6

Minimum stringing conductor sag

7
a

Conductor

Conductor

Conductor

Conductor

Type A
0.11
0.25
0.42
0.60
0.80
1.00

Type B
0.20
0.40
0.60
0.81
1.05
1.30

Type C
0.20
0.40
0.65
0.90
1.20
1.50

Type D
0.24
0.69

8

clearance margin when
Conductor
stringing c
Type E
m
0.15
0.15
0.40
0.25
0.82
0.40
1.46
0.50
1.67
0.62
2.41
0.75

261

m
10
20
30
40
50
60

2

a For the purpose of Columns 3 to 7 of this Table, conductors are classified as follows:
Type A — Bare hard-drawn copper, insulated hard-drawn copper (other than neutral-screened).
Type B — Bare aluminium.
Type C — Insulated aluminium, insulated annealed copper.
Type D — Neutral-screened, aluminium and annealed copper.
Type E — Neutral-screened, hard-drawn copper.
b Column 2 is not applicable to conductors of Type D or Type E where no spacing is provided between conductors.
AS/NZS 3000:2000

c The additional clearance of Column 8 of this Table is to allow for the additional sag of an aeri al conductor at temperatures above that at which
the conductor is originally strung (see Clause 3.12.3).

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AS/NZS 3000:2000

TABLE D2
MINIMUM SIZE OF INTERMEDIATE, TERMINAL OR ANGLE POSTS FOR AERIAL CONDUCTORS —
a
INSULATED HARD-DRAWN COPPER CONDUCTORS — SQUARE SAWN UNTREATED TIMBER POSTS
1

2

3

Maximum
span length

Free length to
lowest
conductor
support

Depth in
ground

40

60

m
1.0b
2.0b
3.0b
5.0
7.0
1.0b
2.0b
3.0b
5.0
7.0
1.0b
2.0b
3.0b
5.0
7.0

5

6

7

8

9

Size of square timber post, mm

m

1.5
1.6

1.5
1.6

1.5
1.6

4 × 4 mm
3 × 6 mm 2
2 × 10 mm 2
conductors
100
100
100
125
150
100
125
125
150
175
c
100
125c
150c
150c
175c
2

4 × 6 mm
3 × 10 mm 2
2 × 16 mm 2
conductors
100
125
125
150
150
125
150
150
175
175
125
150
175
200
200
2

4 × 10 mm
3 × 16 mm 2
2 × 25 mm 2
conductors
125
125
150
150
175
125
150
175
200
200
150
175
200

2

4 × 16 mm
3 × 25 mm 2
2 × 35 mm 2
conductors
150
175
175
200
200
150
175
200

175
200

2

4 × 25 mm
3 × 35 mm 2
2 × 50 mm 2
conductors
150
175
175
200

175
200

175

2

4 × 35 mm
3 × 50 mm 2
2 × 70 mm 2
conductors
175
200
200

175

200

a Untreated hardwood timber with durability of Class 1 and Class 2 (see AS 2209), and strength of grade S3 or better.
b Struts or extensions to structures.
2
c These values are for the maximum 50 m span applicable to 10 mm insulated hard-drawn copper conductors in accordance with Table 3.9.

2

262

m
20

4

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TABLE

D3

MINIMUM SIZE OF INTERMEDIATE, TERMINAL OR ANGLE POSTS FOR AERIAL CONDUCTORS —
INSULATED HARD-DRAWN COPPER CONDUCTORS — ROUND UNTREATED TIMBER POLESa
1
Maximum
span length
m
20

60

b
c

b

1.0
2.0b
3.0b
5.0
7.0
1.0b
2.0b
3.0b
5.0
7.0
1.0b
2.0b
3.0b
5.0
7.0

4

5

6

Depth in
ground
m

4 ×4 mm
3 ×6 mm 2
2 ×10 mm 2
conductors

4 ×6 mm
3 ×10 mm 2
2 ×16 mm 2
conductors

4 ×10 mm 2
3 ×16 mm 2
2 ×25 mm 2
conductors

1.5
1.6

1.5
1.6

1.5
1.6

125
125
125
150
175
125
150
175
175
200
c
125
150c
175c
175c
200c

125
150
150
175
175
150
175
175
200
200
150
175
200
225
225

150
175
175
200
200
175
200
200
225
225
175
200
225
250
275

7

8

9

4 ×16 mm 2
3 ×25 mm 2
2 ×35 mm 2
conductors

4 ×25 mm 2
3 ×35 mm 2
2 ×50 mm 2
conductors

4 ×35 mm 2
3 ×50 mm 2
2 ×70 mm 2
conductors

175
200
200
225
225
175
225
250
250
275
200
225
250
275
300

200
200
225
250
250
200
250
250
300
300
200
250
275
325
350

200
225
225
250
275
225
250
275
300
325
225
275
300
350
375

Size of round timber pole, mm
2

2

Untreated hardwood timber with durability of Class 1 and Class 2 (see AS 2209), and strength of grade S3 or better.
Struts or extensions to structures.
2
These values are for the maximum 50 m span applicable to 10 mm insulated hard-drawn copper conductors in accordance with Table 3.9.

AS/NZS 3000:2000

a

Free length to
lowest
conductor
support
m

3

263

40

2

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MINIMUM SIZE OF INTERMEDIATE, TERMINAL OR ANGLE POSTS FOR AERIAL CONDUCTORS — INSULATED
HARD-DRAWN COPPER CONDUCTORS — ROUND, FULL-LENGTH PRESERVATIVE-TREATED POLESa
1
Maximum span
length
m
20

60

Free length to
lowest
conductor
support
m
1.0b
2.0b
3.0b
5.0
7.0
1.0b
2.0b
3.0b
5.0
7.0
1.0b
2.0b
3.0b
5.0
7.0

3

4

Depth in
ground

4 ×4 mm
3 ×6 mm 2
2 ×10 mm 2
conductors
125
150
150
150
175
150
150
175
175
200
c
150
175c
175c
200c
200c

m

1.5
1.6

1.5
1.6

1.5
1.6

5
2

6

7

8

Size of round timber pole, mm
4 ×6 mm
4 ×10 mm 2
4 ×16 mm 2
4 ×25 mm 2
3 ×10 mm 2
3 ×16 mm 2
3 ×25 mm 2
3 ×35 mm 2
2
2
2
2 ×16 mm
2 ×25 mm
2 ×35 mm
2 ×50 mm 2
conductors conductors conductors conductors
150
150
175
200
150
175
200
225
150
175
200
225
175
200
225
250
200
200
250
275
150
175
200
200
175
200
225
250
200
200
250
275
200
225
275
300
225
250
300
325
150
175
200
225
175
200
250
250
200
225
275
300
225
250
300
325
250
275
325
375
2

9
4 ×35 mm 2
3 ×50 mm 2
2 ×70 mm 2
conductors
225
225
250
275
300
225
275
300
325
350
250
275
325
375
400

a. Preservative-treated hardwood or softwood timbers with durability of Class 4 or better (see AS 2209), and strength of grade S6 or better.
b Struts or extensions to structures.
2
c These values are for the maximum 50 m span applicable to 10 mm insulated hard-drawn copper conductors in accordance with Table 3.9.

264

40

2

AS/NZS 3000:2000

TABLE D4

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TABLE D5
MINIMUM SIZE OF INTERMEDIATE, TERMINAL OR ANGLE POSTS FOR AERIAL CONDUCTORS —
INSULATED HARD-DRAWN COPPER CONDUCTORS — STEEL POLES AND PIPES a
1
Maximum span
length
m
20

60

4

5

6

7

8

9

4 × 25 mm 2
3 × 35 mm 2
2 × 50 mm 2
conductors
102 × 4.88
114 × 5.4
140 × 4.88
165 × 4.88
168 × 6.35
114 × 5.4
165 × 4.88
168 × 6.35
219 × 6.35
219 × 8.18
140 × 4.88
168 × 6.35
219 × 4.78
219 × 8.18
273 × 6.35

4 × 35 mm 2
3 × 50 mm 2
2 × 70 mm 2
conductors
114 × 5.4
140 × 4.88
140 × 5.4
168 × 6.35
168 × 7.11
140 × 4.88
168 × 6.35
219 × 4.78
219 × 6.35
219 × 8.18
140 × 5.4
168 × 7.11
219 × 6.35
273 × 6.35
273 × 9.27

b

Depth in
ground
m

1.5
1.6

1.5
1.6

1.5
1.6

4 × 4 mm
3 × 6 mm 2
2 × 10 mm 2
conductors
60 × 3.6
60 × 4.5
76 × 3.6
89 × 4.0
102 × 4.0
76 × 3.6
89 × 4.0
102 × 4.0
114 × 4.5
140 × 4.88
d
76 × 3.6
102 × 4.0d
114 × 4.5d
140 × 4.88 d
140 × 4.88 d
2

4 × 6 mm
3 × 10 mm 2
2 × 16 mm 2
conductors
60 × 4.5
76 × 4.5
89 × 4.0
102 × 4.0
114 × 4.5
76 × 4.5
102 × 4.0
114 × 4.5
140 × 4.88
140 × 5.4
89 × 4.0
114 × 4.5
140 × 4.88
165 × 4.88
168 × 6.35
2

Size of steel pipe , mm
4 × 10 mm 2
4 × 16 mm 2
3 × 16 mm 2
3 × 25 mm 2
2
2 × 25 mm
2 × 35 mm 2
conductors conductors
76 × 3.6
89 × 4.88
89 × 4.88
102 × 4.88
102 × 4.88
114 × 5.4
114 × 5.4
140 × 4.88
140 × 4.88
165 × 4.88
89 × 4.88
102 × 4.88
114 × 5.4
140 × 4.88
140 × 4.88
165 × 4.88
165 × 5.4
219 × 4.78
168 × 6.35
219 × 6.35
102 × 4.88
114 × 5.4
140 × 4.88
165 × 4.88
165 × 4.88
168 × 7.11
168 × 6.35
219 × 6.35
219 × 4.78
219 × 8.18

Steel poles and pipes are to be protected against corrosion.
Dimensions for pipe sizes are outside diameter and thickness.
Struts or extensions to structures.
2
These values are for the maximum 50 m span applicable to 10 mm insulated hard-drawn copper conductors in accordance with Table 3.9.

AS/NZS 3000:2000

a
b
c
d

Free length to
lowest
conductor
support
m
1.0c
2.0c
3.0c
5.0
7.0
1.0c
2.0c
3.0c
5.0
7.0
1.0c
2.0c
3.0c
5.0
7.0

3

265

40

2

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AS/NZS 3000:2000

TABLE D6
MINIMUM SIZE OF INTERMEDIATE, TERMINAL OR ANGLE POSTS FOR AERIAL CONDUCTORS —
BARE ALUMINIUM CONDUCTORS — SQUARE SAWN UNTREATED TIMBER POSTS a
1

2

3

Maximum span
length

Free length to
lowest
conductor
support

Depth in
ground

4

5

m
20

40

60

m
1.0b
2.0b
3.0b
5.0
7.0
1.0b
2.0b
3.0b
5.0
7.0
1.0b
2.0b
3.0b
5.0
7.0

m

1.5
1.6

1.5
1.6

1.5
1.6

7

Size of square sawn timber pole,
4 ×49 mm 2
4 ×34 mm 2
3 ×77 mm 2
2
2
3 ×49 mm
3 ×34 mm
2 ×111 mm 2
2
2
2 ×49 mm
2 ×77 mm
2 ×124 mm 2
conductors conductors conductors
100
100
100
100
100
125
100
125
125
125
150
150
150
150
175
100
125
125
125
150
150
150
150
175
175
175
200
175
200

125
125
150
150
150
175
175
175
200
200
200

200

8

9

4 ×77 mm 2
3 ×111 mm 2
2 ×124 mm 2
conductors
125
150
150
175
200
150
175
200

150
200

4 ×111 mm
4 ×124 mm 2
conductors
125
150
175
175
200
175
200

200

mm

a Untreated hardwood timber with durability of Class 1 and Class 2 (see AS 2209), and strength of grade S3 or better.
b Struts or extensions to structures.

2

266

2 ×34 mm
conductors
75
100
100
125
150
100
125
125
150
175
100
125
150
175
200
2

6