While on-site at a customer's location performing preventive maintenance to the primary switch our technicians came across a severely burnt arc chute. This was caused by the arcing blade becoming stuck. The electrical current arced and burnt a hole in the arc chute. Powertech replaced the arc chute and serviced the switch.
Primary switch at customer's location blew up. The picture is of the copper bus in the primary switch. The insulation failed and burnt a hole to the copper bus piece. This resulted in the main breaker opening and causing loss of power to a third of the facility. Powertech repaired the insulation to the copper bus piece and reinstalled.