Technical information

1.7 Low-Voltage Limited EnergyCircuit . . . . . . . . . . . . . . . . . . . 81

1.7.1 Supply.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

1.7.2 Overcurrent Protection . . . . . . . . . . . . . . . . . . . . . . 82

1.7.3 External Wiring and Terminal . . . . . . . . . . . . . . . . . . . 83

1.7.4 Internal Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

1.7.5 Circuits and components excluded from class 2 and

Low-voltage limited-energycircuits . . . . . . . . . . . . . . . . 84

1.8 Transformer and self transformer protection . . . . . . . . . . . . . . 84

1.8.1 Protections allowed.. . . . . . . . . . . . . . . . . . . . . . . 88

1.9 Control of the temperature in the panel . . . . . . . . . . . . . . . . . 89

Industrial Machinery

1. NEC 2005 and article 670 on Industrial Machinery.. . . . . . . . . . . . 90

1.1 Machinery categories in "Industrial Machinery" . . . . . . . . . . . . . 91

2. Special requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

2.1 Fuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

2.2 Sizing of the feeder overcurrent protection . . . . . . . . . . . . . . . 92

2.3 Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

2.4 Minimum power cable section . . . . . . . . . . . . . . . . . . . . . . 92

2.5 Conductor colours. . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

3. Short Circuit Current Rating . . . . . . . . . . . . . . . . . . . . . . . . . 94

3.1 Short Circuit Current Rating . . . . . . . . . . . . . . . . . . . . . . . 94

3.1.1 National Electric Code Changes Overview. . . . . . . . . . . . 94

3.1.2 Determining Your Panel Short Circuit Current Rating . . . . . . 95

3.1.3 High Fault Short Circuit Current Ratings . . . . . . . . . . . . . 99

3.1.4 High Fault Component Short Circuit Current Rating . . . . . . 100

3.1.5 Marking Yo ur Panel . . . . . . . . . . . . . . . . . . . . . . . . 101

TABLE OF CONTENTS