Hypertherm HT4400 HySpeed Plasma Arc Cutting System - Manual (Page 165)

APPENDIX A – SYSTEM GROUNDING
a-2 HYPERTHERM Plasma Systems
All modules may also be installed near the work table, and grounded directly to it (Figure a-2). Do not ground the
ignition console directly to the power supply.
The customer must furnish all conductors for equipment grounding. Grounding conductors may be purchased
through Hypertherm in any length specified by the customer (Part No. 047058). The conductor may also be
purchased locally, using a minimum 8 AWG UL Type MTW cable (USA specification) or the appropriate cable
specified by national and local codes.
Consult the appropriate manufacturer’s instructions to ground equipment that does not receive power from the
power supply.
Work Table Grounding
If a supplementary ground rod is installed near the worktable to reduce EMI, it must be connected directly to the PE
ground of the building structure, connected to the service ground; or to earth, providing the resistance between the
ground rod and the service ground meets national or local codes. Place the supplementary ground rod within 20 ft
(6 m) of the worktable according to national or local codes.
If any module is grounded to the work table, the work table must be grounded to the power supply, or the
configuration must be changed to comply with applicable national and local electrical codes.
A ferrite choke can be placed in the conductor between the work table ground rod and the PE ground, with a
number of turns through the choke to isolate the safety ground (at 60 Hz) from any electromagnetic interference
(frequencies above 150 Khz). The more turns the better. A suitable ferrite choke can be made by wrapping 10 turns
or more of the ground lead through Magnetics part number 77109-A7, Fair-Rite part number 59-77011101, or other
equivalent ferrite choke. Locate the choke as close as possible to the plasma power supply.