Unformatted text preview: can cause a fire in the area where the overload exists, even inside a wall. In order to prevent too much current in a circuit, a circuit breaker or fuse is placed in the circuit. If there is too much current in the circuit, the breaker "trips" and opens like a switch. If an overloaded circuit is equipped with a fuse, an internal part of the fuse melts, opening the circuit. Both breakers and fuses do the same thing: open the circuit to shut off the electrical current. If the breakers or fuses are too big for the wires they are supposed to protect, an overload in the circuit will not be detected and the current will not be shut off. Overloading leads to overheating of circuit components (including wires) and may cause a fire. You need to recognize that a circuit with improper overcurrent protection devices--or one with no overcurrent protection devices at all-- is a hazard. Overcurrent protection devices are built into the wiring of some electric motors, tools, and electronic devices. For example, if a tool draws too much current or if it overheats, the current will be shut off from within the device itself. Damaged tools can overheat and cause a fire. You need to recognize that a damaged tool is a hazard. circuit breaker--an overcurrent protection device that automatically shuts off the current in a circuit if an overload occurs trip--the automatic opening (turning off) of a circuit by a GFCI or circuit breaker fuse--an overcurrent protection device that has an internal part that melts and shuts off the current in a circuit if there is an overload Circuit breakers and fuses that are too big for the circuit are dangerous (e.g., using a 30 amp fuse in a 20 amp circuit). Circuits without circuit breakers or fuses are dangerous. Damaged power tools can cause overloads. Damaged equipment can overheat and cause a fire. Wet conditions hazards
Working in wet conditions is hazardous because you may become an easy path for electrical current. If you touch a live wire or other electrical component--and you are standing in even a small puddle of water--you will receive a shock. Damaged insulation, equipment, Wet conditions are dangerous. Section 5 Page 31 S A F E T Y M O D E L S TAG E 1 -- r E C O G N I Z I N G H A Z A r D S
or tools can expose you to live electrical parts. A damaged tool may not be grounded properly, so the housing of the tool may be energized, causing you to receive a shock. Improperly grounded metal switch plates and ceiling lights are especially hazardous in wet conditions. If you touch a live electrical component with an uninsulated hand tool, you are more likely to receive a shock when standing in water. But remember: you don't have to be standing in water to be electrocuted. Wet clothing, high humidity, and perspiration reduce resistance and increase your chances of being electrocuted. You need to recognize that all wet conditions are hazards. n electrical circuit in a damp A place without a GFCI is dangerous! A GFCI reduces the danger. Additional hazards
In addition to electrical hazards, other types of hazards are present at job sites. Remember that all of these hazards can be controlled. here are non-electrical hazards T at job sites, too. There may be chemical hazards. Solvents and other substances may be poisonous or cause disease. Frequent overhead work can cause tendinitis (inflammation) in your shoulders. Overhead work can cause long-term shoulder pain. Page 32 Section 5 Intensive use of hand tools that involve force or twisting can cause tendinitis of the hands, wrists, or elbows. Use of hand tools can also cause carpal tunnel syndrome, which results when nerves in the wrist are damaged by swelling tendons or contracting muscles. Frequent use of some hand tools can cause wrist problems such as carpal tunnel syndrome. A 22-year-old carpenter's apprentice was killed when he was struck in the head by a nail fired from a powder-actuated nail gun (a device that uses a gun powder cartridge to drive nails into concrete or steel). The nail gun operator fired the gun while attempting to anchor a plywood concrete form, causing the nail to pass through the hollow form. The nail traveled 27 feet before striking the victim. The nail gun operator had never received training on how to use the tool, and none of the employees in the area was wearing PPE. In another situation, two workers were building a wall while remodeling a house. One of the workers was killed when he was struck by a nail fired from a powder-actuated nail gun. The tool operator who fired the nail was trying to attach a piece of plywood to a wooden stud. But the nail shot though the plywood and stud, striking the victim. Below are some OSHA regulations that should have been followed. Employees using powder- or pressure-actuated tools must be trained to use them safely. Employees who operate powder- or pressure-actuated tools must be trained to avoid firing into easily penetrated materials (like plywood). In areas where workers could be exposed to flying nails, a...
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This document was uploaded on 03/14/2014 for the course ECE 482 at University of Tennessee.
- Spring '09