In Ontario, Canada, there has recently been a well-documented case of an electrical explosion and at least one fatal electrocution due to damage in a facility’s electrical system where the root cause was identified as stray welding current (SWC). Often in industrial or construction environments, this trouble occurs due to a very simple error in setup by a welder. But how? Stray welding currentĪ stray current is a flow of electric current through unintended conductors such as building structures, electrical grounding or bonding conductors, or other equipment due to electrical supply system imbalances or improper equipment hookup. What is going on? Did a something come loose? Could it be a lightning strike? Is the foreign-made machine incompatible with our electrical network? Is the damage being caused by 1st, 3rd, 5th, 7th, or 9th level harmonics? Why hasn’t the over-current protection system reacted and tripped a breaker? There’s a very good chance that the problem has something to do with the common arc welding process being used to attach mechanical hardware as part of the new machine installation. If it continues, soon a live phase conductor will be in contact with a red-hot grounding wire, and an unsuspecting worker could be seriously hurt or even killed when they investigate the problem. Hundreds of amperes are flowing in an uncontrolled fashion, surging through metallic conduit and panels, melting EMT connectors, arcing the bonding wires in a 3-phase receptacle, and burning through the insulation of the power cord to the brand new, million-dollar machine from Europe.
Now that the power is on, the machinery installation crews are busy getting everything ready for production.īut suddenly there is trouble in the plant. The engineers have produced a state-of-the-art design the qualified electricians have completed a professional installation with quality hardware and the thorough electrical inspections verifying that everything is up to Code are complete. The new extension to the factory is finally finished.
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