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You should always refer to your local electrical code to be sure you are grounding to code. Generally, use a grounding
wire with a cross section of more than 14 mm and a resistance to ground of less than 100 ohms. This wire size should be
greater than AWG (American Wire Gauge) No. 5 and SWG (British Legal Standard Wire Gauge) No.6.
Generally, the machine should be grounded to a separate grounding rod. If an independent ground cannot be provided
for the machine, prepare the ground connection as follows:
1. Connect a single conductor to its own grounding terminal. This will avoid possible serious accidents resulting from
ground currents that might otherwise flow in the NC machine if a peripheral device should malfunction.
2. Be careful when using concrete reinforcing rods as grounding points. These reinforcing rods often are used to
ground equipment because they usually offer a resistance to ground of less than 100 ohms. In doing so, make the
connection as follows: (This also applies to connecting ground wires to regular grounding terminals)
3. Do not use the same grounding reinforcing rod or grounding terminal for other devices since this could lead to line
noise such as produced electric welders and high frequency quenching machines.
4. Use a grounding terminal with an adequate electrical performance rating and which is durable.
5. A separate grounding wire should be used, one whose length is as short as possible.
6. Check the resistance to ground by actual measurement.
7. This should measure less than 100 ohms if the single device is connected to its own grounding rod.
Desirable Independent Grounding: Earth resistance: Less than 100 ohms Common Grounds:
Resistance to ground = 100/the number of devices connected to the grounding (Ω)
NEVER GROUND EQUIPMENT IN SERIES!
Connection of Power Line
1. Make sure that the incoming power is compatible with the requirements of the machine tool (voltage, amperage,
phasing). All this information can be found on the machine’s serial number tag.
2. Power wires, grounding and over-voltage protection should comply with the local electrical code.
3. DO NOT connect if the incoming power is different from the power requirements of the machine. Contact a
qualified electrician.
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