Contractor Safety Share

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Hidden Hazards when Pin Welding

Hidden Hazards when Pin Welding




An employee was pin welding insulation onto a long run of duct when an arc flash occurred.  During the pin welding process, it is normal for the ground clamp to be attached to the support pieces holding up the duct in order to complete the electrical current.


The employee didn’t realize that support wire holding up a temporary light was resting against another support holding up the duct.  As the employee went to make a weld through the insulation, the electrical current found an easier route and went to ground on the wire supporting the temporary light.  The wire was severed due to the arc and resulted in the temporary light falling to the ground.  Luckily, no one was near the light when it fell.

Factors to consider at your site and/or project include, but not limited to the following:

  • Ensure that the person operating the pin welder is competent and trained in all aspects of the pin welding process.
  • Make certain that nothing is touching or resting against the duct system including all support pieces.  This will help eliminate the potential of grounding to another source.
  • Follow the manufacturer’s recommendations when operating the pin welder.
  • Whenever possible, ground directly to piece of duct that is being welding on.  In most cases, it’s not possible to ground directly to the duct because the duct is already enclosed with the insulation.
Consider this example as you complete today’s work activities.

Safety Flash Action Items:
  • Date Contractor Safety Flash posted for all employees to review: _______________
  • Safety Talk meeting date: _______________
  • Full employee attendance and participation at safety meeting to review this incident (documentation required).
  • Employees understand urgency in protecting themselves and others.
  • Supervisors and Employees are clear which items shared in this Safety Flash are mandatory.
  • Employees/Supervisors will focus on recommended actions during future work activities of a similar nature.
Contract Firm Management Rep Signature____________________

THINK about the hazards associated with your particular work, and the steps that can be taken to increase safety on your job.


If you have questions about this CONTRACTOR SAFETY FLASH, please contact

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