Inspection Detail

Inspection: 316270206 - Siemens Industry Inc

Inspection Information - Office: Hi-E-Honolulu

Investigation Summary

At approximately 9:15 a.m. on April 25, 2013, Employee #1, #2, and #3 were preparing for a scheduled test of a motor controller (MC) starter system in the control building of a water supply deep well and reservoir facility. The MC was a Series 81000 motor controller manufactured by Siemens Industry Inc. that would serve a 600 hp submersible pump, operating on 3-phase, 4,160 volt electric power. The pump was to be installed in the well at the site. Employee #1 was a senior engineer working for the Siemens. He was the primary designer of the Series 81000 and had 20 years of experience with similar equipment. Employee #2 was a design engineer for Phasetronics LLC, which manufactured a motor starter that was incorporated in the Siemens motor controller starter system. Employee #3 was the sole proprietor of Scada & Control Systems LLC, which had purchased and provided the electronic and control systems equipment for the deep well and reservoir facility. Employee #1 and #2 arrived at the facility with Employee #3 earlier in the week to troubleshoot and repair the MC starter system, which had failed during initial testing in August 2012. The MC system was in a metal cabinet in one of two banks of cabinets that faced each other 6.58 ft apart inside the control building. The door of the MC cabinet was approximately 90 in. high and 36 in. wide. The interior of the cabinet was divided into three physically separate compartments from top to bottom with the 120 volt MC system control panel in the middle compartment. The bottom compartment contained various wiring, leads for the three phases of the pump motor and a movable carriage that held contactors, fuses and other circuit parts for the pump motor and the MC control panel. The carriage was 18 in. wide. It fit on a track on the right side of the bottom compartment and occupied slightly over half of the compartment's 35 in. interior width. It was racked (moved forward or back) by a lever next to the cabinet door on the lower right side. At its rearmost position, the contactors engaged the main busbar and energized the system at 4,160 volts. This was stepped down to 120 volts for the control panel. An interlock inside the cabinet was designed to accept a tab on the cabinet door so that the lever could not be moved to rack the contactors if the door were open. With the carriage removed from the cabinet and the system de-energized, Employee #1 installed a monitoring instrument behind the control panel and attached a cable from it to one of the motor leads at the left rear of the bottom section. He and Employee #3 then placed the contactor carriage back on its track. Employee #1 knelt on the concrete floor in front of the open cabinet and used a screwdriver to defeat the interlock. He told Employee #3 to slowly raise the lever to rack the contactor (which would engage the busbar) while he watched to see that the carriage did not pinch the instrument cable. Employee #2 stood a few feet away by the opposite bank of cabinets preparing a laptop computer to monitor the system test. None of them was wearing any form of electrical protective equipment, such as insulated gloves or gauntlets, face shield, or flame resistant clothing. After the contactor was racked, which energized the exposed parts on the carriage at 4,160 volts, Employee #1 said the cable "looked okay." As Employee #2 and #3 turned away, Employee #1 reached with his left arm into the cabinet and his forearm contacted one of the energized parts on the carriage. Employee #3 saw Employee #1's body shaking and tried to pull him away from the cabinet while he threw the lever to rack out the contactor. In the process, he received an electric shock. Employee #2 was also shocked when his left arm touched the open cabinet door as he also tried to pull Employee #1 away. Employee #2 threw the main breaker for the building, which was roughly 12 ft to the left of the MC cabinet. He and Employee #3 pulled Employee #1 out of the cabinet and onto hi

Keywords: BURN, INSTALLING, PPE, ELECTRICAL TESTING, ELECTROCUTED, STRUCK AGAINST, ELEC CIRC PART--MISC, ELECTRIC SHOCK