Grounding for Arc
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 H8151 welder is grounded through the power cord and power grid. The welder's inter- nal welding circuit is insulated from the external enclosure. However, to avoid shocking hazards in the event that this internal insulation should fail, you must establish a separate earth ground for the welder's external enclosure. This will ensure that the metal enclosure of the welder and the internal welding circuit are at the same electrical potential.
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 H8151 external enclosure is located on the right rear of the welder (see Figure 4).
Workpiece Ground
The incoming power circuit to the welder and the welding circuit are two separate circuits that must have separate grounds. The welding circuit consists of the internal components of the welder, the welding cables, the electrode holder, the work clamp, and the workpiece.
In the publication Safety in Welding, Cutting, and Allied Processes, ANSI Publication Z49.1, 11.3.2.1, it is specified 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 welding circuit are never con- nected. Failure to comply with this warning could result in serious property damage, personal injury, or death.
However, you must also avoid "double grounding" of the workpiece. The ANSI Publication Z49.1 publication warns that "Care shall be taken to avoid the flow of welding current through a con- nection intended only for safety grounding since the welding current may be of a higher magnitude 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.
Figure 4. Location of external enclosure grounding terminal on the rear of the Model H8151.
H8151 230V Mini Welder |
