– 7 –
7
. WIRING
(1) Wiring procedures
Wiring work must be done according to the Electrical Equipment Technical Standards and Interior Wiring
Code by a trained worker using suitable wiring tools. Working with live wires is dangerous. Always turn the
power OFF before starting the work. The outline of the wiring requirements is shown in Table 5. If the wiring
distance is long, the voltage drop will increase.
In this case, wire so that the voltage drop is 2% or less during
motor operation.
Table 5 Motor wiring
Output
(kW)
Min. wire thickness
*1
Max. distance of
electrical wiring
*2
Overcurrent circuit breaker (A)
*3
Rated current of
excess graduation
current meter for
motor (A)
Min. grounding wire
thickness
Full-voltage
starting
Using starter
(Star-delta starter)
200V
class
400V
class
200V
class
400V
class
200V
class
400V
class
200V
class
400V
class
200V
class
400V
class
200V
class
400V
class
0.75 1.6 mm 1.6 mm 54 m
217 m
15
15
-
-
5
5
1.6 mm 1.6 mm
1.5
1.6 mm 1.6 mm 32 mm 130 m
30
15
-
-
10
5
1.6 mm 1.6 mm
2.2
1.6 mm 1.6 mm 23 mm 94 m
30
15
-
-
10
5
1.6 mm 1.6 mm
3.7
2.0 mm 1.6 mm 23 mm 60 m
50
30
-
-
15
10
2.0 mm 1.6 mm
5.5
5.5 mm
2
1.6 mm 27 mm 40 m
75
40
40
20
30
15
5.5 mm
2
2.0 mm
7.5
8 mm
2
2.0 mm 31 mm 48 m
100
50
50
30
30
15
5.5 mm
2
2.0 mm
11
14 mm
2
5.5 mm
2
37 mm 57 m
125
75
75
40
60
30
8 mm
2
5.5 mm
2
15
22 mm
2
8 mm
2
43 mm 65 m
125
100
100
50
60
30
8 mm
2
5.5 mm
2
18.5 38 mm
2
14 mm
2
61 mm 93 m
125
100
125
60
100
40
8 mm
2
5.5 mm
2
22
38 mm
2
22 mm
2
51 mm 124 m
150
125
125
75
100
60
8 mm
2
8 mm
2
30
60 mm
2
22 mm
2
62 mm 92 m
200
125
175
100
150
60
14 mm
2
8 mm
2
37
100 mm
2
38 mm
2
86 mm 126 m
250
125
225
125
200
100
22 mm
2
8 mm
2
(*1) The minimum wiring thickness is for when three wires are placed in a conduit (full-voltage starting).
(*2) The guideline for the maximum distance of an electrical wiring is that the voltage drop at the distant end is to be 2% or less for the minimum wire
thickness.
(*3) The overcurrent circuit breaker is for power distribution. To protect a motor with a circuit breaker, choose a circuit breaker commensurate with the
rated output of that particular motor.
There are three classes of general motor insulation, Class E, Class B and Class F. If high-temperature insulation
material such as Class F insulation is used, the temperature in the terminal box will be relatively high. Thus, use
wiring cables and insulation tape that have a high temperature resistance. (Refer to Table 6.)
Table 6 Examples of motor wiring materials
Thermal
class of
motor
Wiring material (Example)
Insulation wiring
Cable
Insulation tape
Tolerable
max.
temp.
°C
Tolerable
max.
temp.
°C
Tolerable
max.
temp.
°C
120(E)
130(B)
Vinyl insulated wire
Rubber insulated wire
Class 2 vinyl insulated wire
Polyethylene insulated wire
Ethylene propylene rubber insulated wire
Bridged polyethylene insulated wire
60
60
75
75
80
90
Vinyl cable
Natural rubber cable
Polyethylene cable
Butyl rubber cable
EP rubber cable
Bridged polyethylene cable
60
60
75
80
80
90
Vinyl adhesive tape
Self-fusing butyl rubber tape
Polyester adhesive tape
60
80
120
155(F) Bridged polyethylene insulated wire
Silicon rubber insulated glass mesh wire
90
180
Bridged polyethylene cable
Silicon rubber cable
90
180
Polyester adhesive tape
Silicon glass adhesive tape
120
180
Remarks : The tolerable max. temperature indicates the main examples for each material. Some products may tolerate a higher temperature. Consult
the manufacturer for details.
(2) Grounding (earthing)
The insulation material of the motor is an insulator and also is a conductor. Thus, the motor has a capacitance
between the ground. If the motor is not grounded, an induction voltage that is approx. 50 to 60% of the power
voltage may be generated in proportion to this capacitance between the frame and ground. To prevent accidents
caused by electric shocks,
always ground the motor according to the Electrical Equipment Technical
Standards Clause 18 to 28. A grounding screw is provided in the motor's terminal box or on the lower part of the
frame. If the grounding screw loosens due to vibration during operation, sparks may be ignited at the grounding
section. Wire the grounding wire so that the grounding screw will not loosen because of the grounding wire
vibrating, and lock the grounding screw.
