Inspection Detail

Inspection: 307153361 - City Of Scottsdale, Parks, Recreation & Facilities

Inspection Information - Office: Arizona Division Of Occupational Safety And Health (Adosh)

Investigation Summary

On December 3, 2003, an employee was addressing a "trouble call" within City Hall for the City of Scottsdale. After responding, he checked the variable frequency drive, VFD, for Air Handler Number 2. He verified that power was engaged and supplying power to the VFD supplied to the air handler. He proceeded to the electrical room in the basement of City hall and after disengaging the circuit on the outside of the panel, he opened the panel door. The three fuses were verified to be in proper working order. The panel door was closed again the switch was reengaged. He then opened, using by-pass, the panel door in the energized mode. He again checked the voltage and no reading was detected on the multimeter. Since there was no power being detected on the line or load side of the fuses, he assumed all power was off in the box. On the load side of the fuse, a small lug nut was tightened to ensure proper contact. Although the fuses were detecting as working properly, he decided to change the fuses believing that the installation of the new fuses could restore power. After returning with the new fuses, he pulled the three fuses beginning with the bottom fuse. After pulling the top fuse with electrically rated fuse pullers, the metal clip holding the line side of the fuse broke away from the mounting bracket. The clip however, was still attached to the panel via a small copper wire. While still holding the fuse pullers, he was able to reach behind him and picked up needle nose pliers from his tool bag. He used the pliers to secure the clip and was able to pull the fuse from the clip. While he did that, he recalled having seeing a spark generated between the fuse and metal clip. He then closed the panel door to deenergize the panel, but the door would not close and the switch box remained energized. He reset the three fuses in place using the fuse pullers. The top fuse was placed in, and while still loose, appeared to be in place, other clip was still secured to the panel. He attempted to call a supervisor to alert him that there was a problem. He contacted the Facilities Maintenance Director and he stated that an electrician would be sent immediately to the scene. The employee returned to the mechanical room. There, he met another a coworker, a HVAC technician, who was sent to the same scene responding to a different trouble call with the HVAC unit, Air Handler Number 1, and specifically, the City Attorney's office located at City Hall. The employee proceeded to demonstrate to the coworker the diagnostic steps he had performed in hopes that the coworker could verify the procedures he had taken. With the three) fuses in place, the employee closed the panel door and deenergized the panel, waited a few moments, and reenergized the panel. He opened the door and checked the three fuses again. Again, no voltage was detected. The employee and the coworker both determined that the switch must be bad and they would wait for an electrician. Not wanting to leave the panel in the energized position, the employee manually activated the mechanical slide was activated by the outside disconnect switch. He pulled out his standard channel locks and used those to grab onto the knob extending down from the slide. As he attempted to move the slide towards the right and put force attempting to move the slide, the panel exploded. The employee was hospitalized and treated for burns.

Keywords: BURN, ELECTRICAL CABINET, ELECTRICAL FAULT