Grounding for
Welding Safety
There are two or more electrical circuits involved in any welding operation. The practice of safely grounding these circuits is documented in vari- ous codes and standards (refer to Additional Sources for Welding Codes and Standards on Page 6).
Welding Machine Ground
When properly connected to a power source, the Model H8154 welder is grounded through the power cord and local power grid. The internal welding circuit of the welder is insulated from the external enclosure. However, to avoid shocking hazards if this internal insulation fails, you must establish a separate earth ground for the welder's external enclosure. This ground will ensure that if a short does occur and the metal enclosure becomes integrated with the welding current, the current will safely dissipate directly through the ground instead of through you.
Note: Refer to the publication NFPA 70, National Electric Code, Article 250, Grounding, and your local electrical codes for the correct method of establishing this ground.
The grounding terminal for the H8154 external enclosure is located on the left rear of the welder (see Figure 5).
Figure 5. Location of external enclosure grounding terminal on the rear of the Model H8154.
Workpiece Ground
The incoming power circuit to the welder and the working welding circuit are two separate circuits that must have separate grounds. The weld- ing circuit consists of the internal components of the welder, the welding cables, the electrode holder/torch assembly, the work clamp, and the workpiece.
ANSI Welding Standards (Z49.1, 11.3.2.1) specify that "Grounding [of the workpiece] shall be done by locating the work on a grounded metal floor or platen, or by connection to a grounded building frame or other satisfactory ground."
Always ensure that the ground for the incom- ing power circuit to the welder and the ground for the working welding circuit are never connected. Failure to comply with this warning could result in death, serious per- sonal injury, or property damage.
You must also avoid "double grounding" the workpiece. ANSI Z49.1 states that "Care shall be taken to avoid the flow of welding current through a connection intended only for safety grounding since the welding current may be of a higher mag- nitude than the grounding conductor can safely carry."
Note: The work lead from the welder is some- times incorrectly referred to as the "ground lead." The work lead from the welder is NOT a ground. The work lead and the ground connection to the workpiece are separate and must NOT be con- nected in any way.
TIG welders use a high frequency current that creates a high