Hypertherm Powermax30 AIR Service Manual - Manual (Page 14)

SC-14 Safety and Compliance
Electromagnetic Compatibility (EMC)
Note: The cutting circuit may or may not be earthed for safety reasons.
Changing the earthing arrangements should only be authorized by a
person who is competent to assess whether the changes will in crease
the risk of injury, for example, by allowing parallel cutting current return
paths which may damage the earth circuits of other equipment. Further
guidance is provided in IEC 60974-9, Arc Welding Equipment, Part 9:
Installation and Use.
Screening and shielding
Selective screening and shielding of other cables and equipment in the
surrounding area may alleviate problems of interference. Screening of the
entire plasma cutting installation may be considered for special
applications.