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Interior ground lug, lower enclosureFigure 3-4:
• Resistance between the copper-clad steel ground rod and the earth ground must
not exceed 25 Ohms.
• On ATEX-certified units, the external ground lug must be connected to the
customer’s protective ground system via 9 AWG (6mm
2
) ground wire. After the
connection is made, apply a non-acidic grease to the surface of the external ground
lug to prevent corrosion.
• The equipment-grounding conductors used between the GC and the copper-clad
steel ground rod must be sized according to your local regulations, the following
specifications apply in the US.
Length Wire
15 ft. (4.6 m) or less 8 AWG, stranded, insulated copper
15 to 30 ft. (4.6 to 9.1 m) 6 AWG, stranded, insulated copper
30 to 100 ft. (9.1 to 30.5 m) 4 AWG, stranded, insulated copper
• All interior enclosure equipment-grounding conductors must be protected by metal
conduit.
• External equipment that is connected to the GC should be powered via isolation
transformers to minimize the ground loops caused by the internally shared safety
and chassis grounds.
3.3.4 Electrical conduit
Follow these general precautions for conduit installation:
• Conduit cutoffs must be cut at a 90-degree angle. Cutoffs must be made by a cold
cutting tool, hacksaw, or by some other approved means that does not deform the
conduit ends or leave sharp edges.
Installation and setup
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Installation and setup
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