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Tuesday, February 06, 2007
Before You Drill, Check The Other Side Of The Wall
On August 28, 2006, at the Idaho National Laboratory, a maintenance worker accidentally drilled into a pressurized fire extinguisher, releasing its contents. The worker was drilling into a wall and did not realize that a recessed fire extinguisher cabinet was located on the other side of the wall. The maintenance worker was not injured.
The worker drilled an inspection hole through the 5/8-inch sheetrock wall, then used a flashlight to look for any obstructions. When he saw no obstruction, he started drilling holes for thermostat wires and the 1/4-inch diameter center guide using a 1-inch hole saw. As the worker began to drill the holes for the center guide, he penetrated the fire extinguisher, which released its contents into the cabinet and into the room where it was located.
Investigators determined that the team leader and workers walked down the area before work began. The workers had a building drawing that indicated which rooms required a thermostat, but the workers received no direction on exact locations where the thermostats should be hung. Instead, they were given latitude to mount the thermostats wherever it was convenient to do so.
The procedure used by the workers permitted removal of a section of wall surface material (i.e., plasterboard or drywall) to inspect for wires or piping in the interior of the wall or to install a receptacle when cutting would not penetrate significantly beyond the interior surface of the wall surface material.
Investigators learned that the worker who drilled into the fire extinguisher did not walk around the wall to see what was on the other side because he did not intend to drill completely through the wall. This event would not have occurred if the worker had simply checked the other side of the wall before drilling. However, the procedure that was used for this work has been changed as a result of the event, and exploratory penetrations must now be performed with a non-powered tool. The revised procedure also does not permit workers to use a power tool before they have made absolutely certain that there is no interference inside the wall. When performing similar drilling tasks, workers and their supervisors should remember that recess-mounted panels, unlike surface-mounted panels, reduce the margin for error when drilling into the wall from the other side. Workers must also remember that the depth of the recess must be accounted for when drilling.
As the following similar events show, inattention to detail and inadequate procedures can have potentially serious consequences.
On October 14, 2003, at Lawrence Livermore National Laboratory, a carpenter mounting a key box set penetrated a 480/277-volt panel on the other side of the wall, resulting in arcing in the panel and between the screw head and the box. The carpenter was mounting the key box set directly below existing boxes and when some anchors did not "bottom-out" on the sheet rock, he thought it was because there were metal studs in the wall. Since he ran out of 2-inch sheet rock screws, he decided to use 3-inch screws, and one of them penetrated the panel box and contacted the bus bar. The screw disintegrated, but the carpenter did not receive an electrical shock.
(ORPS Report DP-OAK--LLNL-LLNL-2003-0036)
Investigators determined that no special procedure or permit was required for the job and that the contractor made no effort to check the other side of the wall for any potential obstructions. The worker, who had worked in the facility for many years, did not consider that there might be a recessed breaker box in the next room because he had never encountered one during previous, similar tasks.
Preventing Hazardous Events
Walk down the work site and perform the following checks.
• Identify equipment you will be working on.
• Ensure that equipment requiring isolation is clearly marked.
• Verify that drawings reflect as-built conditions.
• Identify any safety hazards or issues that may not be immediately apparent (e.g., check the other side of the wall
before work begins).
Drilling into electrical components is far more common across the DOE complex than drilling into a fire extinguisher, but both types of events can stem from similar problems. An analysis performed for an August 2004, Lessons Learned Report on
Electrical Safety at DOE found that about three-quarters of the electrical work occurrences were caused by personnel errors (e.g., procedure violations or inattention to detail) or work control weaknesses. The report presented measures to prevent such occurrences, including walking down the work site to (1) identify equipment to be worked on; (2) ensure that equipment to be isolated is clearly marked; (3) verify or modify drawing to reflect as-built conditions; and (4) identify any additional hazards or safety issues.
Although the maintenance workers and their team leader at Idaho National Laboratory performed a walkdown, it was not thorough enough to identify the safety hazard presented by the fire extinguisher on the other side of the wall.
OSHA regulations in 29 CFR 1926.416(a)(3) state that before work is begun the employer shall ascertain by inquiry or direct observation or by instruments whether any part of an energized electric power circuit, exposed or concealed, is so located that the performance of work may bring any person, tool, or machine into physical or electrical contact with the electrical power circuit. However, workers also must take responsibility for their own safety by performing an independent check of the area in which they intend to perform work tasks that are potentially hazardous.
These events illustrate the importance of taking responsibility for one’s own safety, as well as the necessity of developing procedures that adequately address work performance. Even when a task appears to be uncomplicated and easily performed, workers must check for any unseen hazards before they begin a work task. Supervisors and managers must also ensure that all work is adequately planned, that all hazards are identified, and that appropriate controls are in place before work begins. The simplest “skill of the craft” task can present serious hazards and may require additional, task-specific procedures to ensure worker safety.
The above article is from: U.S. Department of Energy Office of Health, Safety and Security OE Summary 2006-13 November 17, 2006
The worker drilled an inspection hole through the 5/8-inch sheetrock wall, then used a flashlight to look for any obstructions. When he saw no obstruction, he started drilling holes for thermostat wires and the 1/4-inch diameter center guide using a 1-inch hole saw. As the worker began to drill the holes for the center guide, he penetrated the fire extinguisher, which released its contents into the cabinet and into the room where it was located.
Investigators determined that the team leader and workers walked down the area before work began. The workers had a building drawing that indicated which rooms required a thermostat, but the workers received no direction on exact locations where the thermostats should be hung. Instead, they were given latitude to mount the thermostats wherever it was convenient to do so.
The procedure used by the workers permitted removal of a section of wall surface material (i.e., plasterboard or drywall) to inspect for wires or piping in the interior of the wall or to install a receptacle when cutting would not penetrate significantly beyond the interior surface of the wall surface material.
Investigators learned that the worker who drilled into the fire extinguisher did not walk around the wall to see what was on the other side because he did not intend to drill completely through the wall. This event would not have occurred if the worker had simply checked the other side of the wall before drilling. However, the procedure that was used for this work has been changed as a result of the event, and exploratory penetrations must now be performed with a non-powered tool. The revised procedure also does not permit workers to use a power tool before they have made absolutely certain that there is no interference inside the wall. When performing similar drilling tasks, workers and their supervisors should remember that recess-mounted panels, unlike surface-mounted panels, reduce the margin for error when drilling into the wall from the other side. Workers must also remember that the depth of the recess must be accounted for when drilling.
As the following similar events show, inattention to detail and inadequate procedures can have potentially serious consequences.
On October 14, 2003, at Lawrence Livermore National Laboratory, a carpenter mounting a key box set penetrated a 480/277-volt panel on the other side of the wall, resulting in arcing in the panel and between the screw head and the box. The carpenter was mounting the key box set directly below existing boxes and when some anchors did not "bottom-out" on the sheet rock, he thought it was because there were metal studs in the wall. Since he ran out of 2-inch sheet rock screws, he decided to use 3-inch screws, and one of them penetrated the panel box and contacted the bus bar. The screw disintegrated, but the carpenter did not receive an electrical shock.
(ORPS Report DP-OAK--LLNL-LLNL-2003-0036)
Investigators determined that no special procedure or permit was required for the job and that the contractor made no effort to check the other side of the wall for any potential obstructions. The worker, who had worked in the facility for many years, did not consider that there might be a recessed breaker box in the next room because he had never encountered one during previous, similar tasks.
Preventing Hazardous Events
Walk down the work site and perform the following checks.
• Identify equipment you will be working on.
• Ensure that equipment requiring isolation is clearly marked.
• Verify that drawings reflect as-built conditions.
• Identify any safety hazards or issues that may not be immediately apparent (e.g., check the other side of the wall
before work begins).
Drilling into electrical components is far more common across the DOE complex than drilling into a fire extinguisher, but both types of events can stem from similar problems. An analysis performed for an August 2004, Lessons Learned Report on
Electrical Safety at DOE found that about three-quarters of the electrical work occurrences were caused by personnel errors (e.g., procedure violations or inattention to detail) or work control weaknesses. The report presented measures to prevent such occurrences, including walking down the work site to (1) identify equipment to be worked on; (2) ensure that equipment to be isolated is clearly marked; (3) verify or modify drawing to reflect as-built conditions; and (4) identify any additional hazards or safety issues.
Although the maintenance workers and their team leader at Idaho National Laboratory performed a walkdown, it was not thorough enough to identify the safety hazard presented by the fire extinguisher on the other side of the wall.
OSHA regulations in 29 CFR 1926.416(a)(3) state that before work is begun the employer shall ascertain by inquiry or direct observation or by instruments whether any part of an energized electric power circuit, exposed or concealed, is so located that the performance of work may bring any person, tool, or machine into physical or electrical contact with the electrical power circuit. However, workers also must take responsibility for their own safety by performing an independent check of the area in which they intend to perform work tasks that are potentially hazardous.
These events illustrate the importance of taking responsibility for one’s own safety, as well as the necessity of developing procedures that adequately address work performance. Even when a task appears to be uncomplicated and easily performed, workers must check for any unseen hazards before they begin a work task. Supervisors and managers must also ensure that all work is adequately planned, that all hazards are identified, and that appropriate controls are in place before work begins. The simplest “skill of the craft” task can present serious hazards and may require additional, task-specific procedures to ensure worker safety.
The above article is from: U.S. Department of Energy Office of Health, Safety and Security OE Summary 2006-13 November 17, 2006
Labels: Industrial Safety
posted by Steve Hudgik |
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