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Unformatted text preview: the hinges. Do not stand on the top step. 6. When using scaffolding, use a ladder to access the tiers. Never climb the cross braces. 7. Do not use metal ladders. Instead, use ladders made of fiberglass. (Although wooden ladders are permitted, wood can soak up water and become conductive.) 8. Beware of overhead powerlines when you work with ladders and scaffolding. Learn how to use ladders and scaffolding properly.
Section 8 Page 63 S A F E T Y M O D E L S TAG E 3 -- C O N T r O L L I N G H A Z A r D S : S A F E W O r K P r AC T I C E S A crew of 7 workers was painting a 33-foot sign at a shopping mall. The crew used tubular welded frame scaffolding that was 31 feet tall and made up of several tiers. The sign was partially painted when the crew was instructed to move the scaffolding so that concrete could be poured for an access road. The crew moved the scaffolding 30 feet without disassembling it. An overhead powerline was located about 10 feet away from the scaffolding. After the concrete hardened, the workers lifted the scaffolding to move it back to the sign. The top tier came loose, fell, and contacted the powerline. All seven workers were knocked away from the scaffolding. Two died; five were hospitalized. You must take certain precautions when working with scaffolding. Scaffolding should not be moved until all potential safety hazards are identified and controlled. In this case, the scaffolding should have been taken apart before it was moved. Locking pins must be used to secure tiers to one another. Always make sure you have enough time to complete your assignment safely. If you are rushed, you may be more likely to take deadly short-cuts (such as failing to dismantle scaffolding before moving it). Employers must have a written safety program that includes safe work procedures and hazard recognition. Do not do any tasks that you are not trained to do or that you do not feel comfortable doing! A company was contracted to install wiring and fixtures in a new office complex. The third floor was being prepared in a hurry for a new tenant, and daily changes to the electrical system blueprints were arriving by fax. The light fixtures in the office were mounted in a metal grid that was fastened to the ceiling and properly grounded. A 23-year-old male apprentice electrician was working on a light fixture when he contacted an energized conductor. He came down from the fiberglass ladder and collapsed. Apparently, he had contacted the "hot" conductor while also in contact with the metal grid. Current passed through his body and into the grounded grid. Current always takes a path to ground. In this case, the worker was part of that path. He was dead on arrival at a nearby hospital. Later, an investigation showed that the victim had crosswired the conductors in the fixture by mistake. This incorrect wiring allowed electricity to flow from a live circuit on the completed section of the building to the circuit on which the victim was working. Below are some safety procedures that should have been followed in this case. Because they were ignored, the job ended in death. Before work begins, all circuits in the immediate work area must be shut off, locked out, and tagged out--then tested to confirm that they are de-energized. Wiring done by apprentice electricians should be checked by a journeyman. A supervisor should always review changes to an original blueprint in order to identify any new hazards that the changes might create. Page 64 Section 8 Avoid wet working conditions and other dangers
Remember that any hazard becomes much more dangerous in damp or wet conditions. To be on the safe side, assume there is dampness in any work location, even if you do not see water. Even sweat can create a damp condition! Do not work wet--Do not work on circuits or use electrical equipment in damp or wet areas. If necessary, clear the area of loose material or hanging objects. Cover wet floors with wooden planking that can be kept dry. Wear insulating rubber boots or shoes. Your hands must be dry when plugging and unplugging power cords and extension cords. Do not get cleaning solutions on energized equipment. Use a GFCI--Always use a GFCI when using portable tools and extension cords. Avoid wet conditions! Even avoid damp conditions! Avoid overhead powerlines
Be very careful not to contact overhead powerlines or other exposed wires. More than half of all electrocutions are caused by contact with overhead lines. When working in an elevated position near overhead lines, avoid locations where you (and any conductive object you hold) could contact an unguarded or uninsulated line. You should be at least 10 feet away from high-voltage transmission lines. Vehicle operators should also pay attention to overhead wiring. Dump trucks, front-end loaders, and cranes can lift and make contact with overhead lines. If you contact equipment that is touching live wires, you will be shocked and may be killed. If you are in the vehicle,...
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This document was uploaded on 03/14/2014 for the course ECE 482 at University of Tennessee.
- Spring '09