Electrical Grounding; Primary Grounding; Supplemental Grounding - Siemens SINUMERIK 840D Maintenance Manual

2.5 ELECTRICAL
GROUNDING
2.5.1 PRIMARY
GROUNDING
2.5.2 SUPPLEMENTAL
GROUNDING
OCTOBER 2005
WARNING!
The importance of proper grounding CANNOT be over-emphasized! Improper
grounding will result in a wide range of hard-to-diagnose problems in communica-
tions, positioning, spindle motion, etc.
1. The grounding conductor shall be of copper. The material selected shall be
resistant to any corrosive condition existing at the installation or shall be suitably
protected against corrosion.
2. The grounding conductor shall be a No. 8 AWG (10 mm
ground conductor, and must be:
• solid or stranded
• insulated, covered, or bare
• installed in one continuous length without a splice or joint.
3. Individually covered or insulated grounding conductors shall have a continuous
outer finish that is either green, or green with one or more yellow stripes.
4. A No. 8 AWG (10 mm
conductors must be contained within one of the following:
• rigid metal conduit
• intermediate metal conduit
• electrical metallic tubing
5. The ground conductor shall be connected between the VMC's ground bus and the
approved ground bus contained within the voltage supply panel board or enclosure.
6. The VMC branch supply conduit, phase conductors and ground conductors must
be dedicated to a single VMC. They cannot be used to supply any other loads.
1. Supplementary grounding electrodes shall be permitted to augment the equipment
grounding conductor; however, the earth shall not be used as the sole equipment
grounding conductor.
2. The supplemental grounding conductor shall be a No. 6 (16 mm
conductor in the form of a wire, and must be:
• solid or stranded
• insulated, covered or bare
• installed in one continuous length without splice or joint
2
3. A No. 6 (16 mm ) or larger grounding conductor shall be run in one of the following:
• rigid metal conduit
PRE-INSTALLATION PROCEDURES
SIEMENS MAINTENANCE MANUAL
2
) or larger equipment ground conductor and 3 phase
2
) or larger equipment
2
) or larger copper
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