We had the opportunity to repair a customer's damaged section of Square D CP2540G bus duct (copper, 4000-amp, 4-wire). The bus duct shorted across the A, B, and C phases.
The bus duct had arced in one of the port holes that allow bus plugs to attach and draw power from the bus duct system. The resulting arc flash from the short circuit caused the bus bar to be melted and a hole to be blown through the steel housing.
After removing the bus bar from the housing, the damage to the neutral bar is evident (the bar closest to the bottom of the picture below. The neutral bar from the blown port hole has been melted and the insulation has been destroyed. The paired bus bar (CP2540G is a paired phase design) has been blackened by the explosion of the outside leg (where the bus plug was attached).
The damaged sections of the bus bar needed to be replaced. The housing needed repairing, including fixing the hole the explosion had created.
The port hole where the bus plug had been installed had to be replaced. The port hole next to the explosion site had to be replaced as well due to damage from the explosion.
After completing the repairs we reconditioned the section of copper bus duct.
One final image showing the end of the bus duct with the joint stack. The inspection covers have not yet been assembled onto the section of bus duct.
