Normally, the circuit breaker in a circuit is matched to the wire size. However, in older wiring, This hand-held sander has exposed wires and should not be used. The current capacity ampacity of the branch wire could be exceeded. When a wire is too small for the cur-rent it is supposed to carry, the wire will heat up. The heated wire could cause a fire.
When you use an extension cord, the size of the wire you are placing into the circuit may be too small for the equipment. The circuit breaker could be the right size for the circuit but not right for the smaller-gauge extension cord. A tool plugged into the extension cord may use more current than the cord can handle without tripping the circuit breaker. The wire will overheat and could cause a fire.
The kind of metal used as a conductor can cause an electrical hazard. Special care needs to be taken with aluminum wire. Since it is more brittle than copper, aluminum wire can crack and break more easily.
Connections with aluminum wire can become loose and oxidize if not made properly, creating heat or arcing. You need to recognize that inadequate wiring is a hazard. Incorrect wiring practices can cause fires! If you touch live electrical parts, you will be shocked. Exposed electrical parts hazards Electrical hazards exist when wires or other electrical parts are exposed.
Wires and parts can be exposed if a cover is removed from a wiring or breaker box. The overhead wires coming into a home may be exposed. Electrical terminals in motors, appliances, and electronic equipment may be exposed. Older equipment may have exposed electrical parts. If you contact exposed live electrical parts, you will be shocked. You need to recognize that an exposed electrical component is a hazard.
Overhead powerline hazards Most people do not realize that overhead powerlines are usually not insulated. More than half of all electrocutions are caused by direct worker contact with energized powerlines. Powerline workers must be especially aware of the dangers of overhead lines. Due to such incidents, all linemen now wear special rubber gloves that protect them up to 34, volts.
Today, most electrocutions involving overhead powerlines are caused by failure to maintain proper work distances. Overhead powerlines kill many workers! Back to Table of Contents. More like this. Other Resources. This hand-held sander has exposed wires and should not be used. Overloaded wires get hot! Watch out for exposed electrical wires around electronic equipment.
Electrical line workers need special training and equipment to work safely. Shocks and electrocutions occur where physical barriers are not in place to prevent contact with the wires. When dump trucks, cranes, work platforms, or other conductive materials such as pipes and ladders contact overhead wires, the equipment operator or other workers can be killed. If you do not maintain required clearance distances from powerlines, you can be shocked and killed.
The minimum distance for voltages up to 50kV is 10 feet. For voltages over 50kV, the minimum distance is 10 feet plus 4 inches for every 10 kV over 50kV.
Never store materials and equipment under or near over-head powerlines. You need to recognize that overhead powerlines are a hazard. Operating a crane near overhead wires is very hazardous. Five workers were constructing a chain-link fence in front of a house, directly below a 7,volt energized powerline. As they prepared to install foot sections of metal top rail on the fence, one of the workers picked up a section of rail and held it up vertically.
The rail contacted the 7,volt line, and the worker was electrocuted. Such changes shall require the changing and posting of revised capacity and instruction decals or plates. These new ratings or limitations shall be as provided by the manufacturer or other equivalent entity. When working with poles in piles or stacks, work shall be performed from the ends of the poles as much as possible, and precautions shall be taken for the safety of employees at the other end of the pole.
During pole hauling operations, all loads shall be secured to prevent displacement. The requirements for installation, removal, or other handling of poles in pole lines are prescribed in paragraph n of this section which pertains to overhead lines. In the case of hoisting machinery equipped with a positive stop loadholding device, it shall be permissible for the operator to leave his position at the controls while a load is suspended for the sole purpose of assisting in positioning the load prior to landing it.
Prior to unloading steel, poles, crossarms, and similar material, the load shall be thoroughly examined to ascertain that the load has not shifted, that binders or stakes have not broken, and that the load is not otherwise hazardous to employees. Cable reels in storage shall be checked or otherwise restrained when there is a possibility that they might accidentally roll from position.
Employees shall be warned, by such techniques as briefing and tagging at all affected locations, to stay clear while the voltage is applied. Electric power conductors and equipment shall be considered as energized unless the employee can visually determine that they are bonded to one of the grounds listed in paragraph m 4 of this section.
Nonworking open wire communications lines shall be bonded to one of the grounds listed in paragraph m 4 of this section. Temporary bonds used for this purpose shall have sufficient conductivity to carry at least amperes for a period of one second without fusing. Acceptable grounds for protective grounding are as follows:. When attaching grounds bonds , the first attachment shall be made to the protective ground.
When removing bonds, the connection to the line or equipment shall be removed first. Insulating gloves shall be worn during these operations. This bonding is not required where crossings are made on a common crossing pole unless there is an upward change in grade at the pole.
Unless temporary guys or braces are attached, the following poles shall be tested in accordance with paragraph n 3 of this section and determined to be safe before employees are permitted to climb them:. On joint use poles, one power line wire shall be considered as two communication wires for purposes of this paragraph n 2 v.
One of the following methods or an equivalent method shall be used for testing wood poles:. The hammer will produce a clear sound and rebound sharply when striking sound wood.
When decay pockets are indicated, the pole shall be considered unsafe. Also, prod the pole as near the ground line as possible using a pole prod or a screwdriver with a blade at least 5 inches long. If substantial decay is encountered, the pole shall be considered unsafe. Caution shall be exercised to avoid causing power wires to swing together. The force may be applied either by pushing with a pike pole or pulling with a rope.
If the pole cracks during the test, it shall be considered unsafe. Poles or structures determined to be unsafe by test or observation may not be climbed until made safe by guying, bracing or other adequate means. Poles determined to be unsafe to climb shall, until they are made safe, be tagged in a conspicuous place to alert and warn all employees of the unsafe condition. Where the strand crosses above power wires or railroad tracks it may not be tested but shall be inspected in accordance with paragraph n 6 of this section.
On joint lines, the rope shall be passed over the strand using tree pruner handles or a wire raising tool. If two employees are present, both shall grip the double rope and slowly transfer their entire weight to the rope and attempt to raise themselves off the ground. If only one employee is present, one end of the rope which has been passed over the strand shall be tied to the bumper of the truck, or other equally secure anchorage. The employee then shall grasp the other end of the rope and attempt to raise himself off the ground.
Where strand passes over electric power wires or railroad tracks, it shall be inspected from an elevated working position at each pole supporting the span in question. The strand may not be used to support any splicing platform, scaffold or cable car, if any of the following conditions exist:. Unless adequate railings are provided, safety straps and body belts shall be used while working on elevated work platforms such as aerial splicing platforms, pole platforms, ladder platforms and terminal balconies.
Safety straps and body belts shall be worn when working at elevated positions on poles, towers or similar structures, which do not have adequately guarded work areas. Before installing or removing wire or cable, the pole or structure shall be guyed, braced, or otherwise supported, as necessary, to prevent failure of the pole or structure. When cranes, derricks, or other mechanized equipment are used for setting, moving, or removing poles, all necessary precautions shall be taken to avoid contact with energized power conductors or equipment.
For voltages not exceeding 15kV to ground, insulating gloves shall have a breakdown voltage of at least 17kV. To the extent feasible, remain on the vehicle as long as the possibility of contact exists.
As a last resort, if a blanket is not available, the employee may jump cleanly from the vehicle. Climbing and working are prohibited above the level of the lowest electric power conducter on the pole exclusive of vertical runs and street light wiring , except:.
The provisions of this paragraph apply to the guarding of manholes and street openings, and to the ventilation and testing for gas in manholes and unvented vaults, where telecommunications field work is performed on or with underground lines.
Examples of manhole worksite hazards which shall be considered to constitute a safety hazard include, but are not limited to:. While work is being performed in a manhole occupied jointly by an electric utility and a telecommunication utility, an employee with basic first aid training shall be available in the immediate vicinity to render emergency assistance as may be required.
The employee whose presence is required in the immediate vicinity for the purposes of rendering emergency assistance is not to be precluded from occasionally entering a manhole to provide assistance other than in an emergency. The requirement of this paragraph o 3 does not preclude a qualified employee, working alone, from entering for brief periods of time, a manhole where energized cables or equipment are in service, for the purpose of inspection, housekeeping, taking readings, or similar work if such work can be performed safely.
Ladders shall be used to enter and exit manholes exceeding 4 feet in depth. When open flames are used in manholes, the following precautions shall be taken to protect against the accumulation of combustible gas:. Employers shall insure that employees do not look into an open waveguide which is connected to an energized source of microwave radiation.
The lower half of the warning symbol shall include the following: Radiation in this area may exceed hazard limitations and special precautions are required. When an employee works in an area where the electromagnetic radiation exceeds the radiation protection guide, the employer shall institute measures that insure that the employee's exposure is not greater than that permitted by the radiation guide.
Such measures shall include, but not be limited to those of an administrative or engineering nature or those involving personal protective equipment. Simultaneous contact with two energized conductors will also cause electric shock which may result in serious or fatal injury. Reliance shall not be placed on their dielectric capabilities.
Aerial lifts include the following types of vehicle-mounted aerial devices used to elevate personnel to jobsites above ground:. These devices are made of metal, wood, fiberglass reinforced plastic FRP , or other material; are powered or manually operated; and are deemed to be aerial lifts whether or not they are capable of rotating about a substantially vertical axis. This consists of a platform, approximately 3 ft. It is furnished with fiber or synthetic ropes for supporting the platform from aerial strand, detachable guy ropes for anchoring it, and a device for raising and lowering it with a handline.
A small tent usually constructed of vinyl coated canvas which is usually supported by light metal or plastic tubing. It is designed to protect employees in inclement weather while working on ladders, aerial splicing platforms, or aerial devices. Electrically connected to a source of potential difference, or electrically charged so as to have a potential significantly different from that of the earth in the vicinity.
The term live is sometimes used in the place of the term current-carrying, where the intent is clear, to avoid repetition of the longer term. A physical obstruction which is intended to prevent contact with energized lines or equipment, or to prevent unauthorized access to work area. An electrical connection from one conductive element to another for the purpose of minimizing potential differences or providing suitable conductivity for fault current or for mitigation of leakage current and electrolytic action.
A conductor with insulation, or a stranded conductor with or without insulation and other coverings single-conductor cable , or a combination of conductors insulated from one another multiple-conductor cable. A protective covering applied to cables. A conductor or system of conductors through which an electric current is intended to flow. The conductors and their supporting or containing structures for telephone, telegraph, railroad signal, data, clock, fire, police-alarm, community television antenna and other systems which are used for public or private signal or communication service, and which operate at potentials not exceeding volts to ground or volts between any two points of the circuit, and the transmitted power of which does not exceed watts.
When communications lines operate at less than volts to ground, no limit is placed on the capacity of the system. Specifically designed communications cables may include communication circuits not complying with the preceding limitations, where such circuits are also used incidentally to supply power to communication equipment. A material, usually in the form of a wire, cable, or bus bar, suitable for carrying an electric current. Intentionally connected to earth through a ground connection or connections of sufficiently low impedance and having sufficient current-carrying capacity to prevent the build-up of voltages which may result in undue hazard to connected equipment or to persons.
A general term which includes materials, fittings, devices, appliances, fixtures, apparatus, and similar items used as part of, or in connection with, a supply or communications installation. That conductive body, usually earth, to which an electric potential is referenced. A conductive connection, whether intentional or accidental, by which an electric circuit or equipment is connected to reference ground.
The connecting or establishment of a connection, whether by intention or accident, of an electric circuit or equipment to reference ground. A small tent usually constructed of vinyl coated canvas supported by a metal or plastic frame.
Its purpose is to protect employees from inclement weather while working at buried cable pedestal sites or similar locations. A system or circuit conductor which is intentionally grounded. A system of conductors in which at least one conductor or point usually the middle wire, or the neutral point of transformer or generator windings is intentionally grounded, either solidly or through a current-limiting device not a current-interrupting device. Grounding conductor. A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode.
Separated from other conducting surfaces by a dielectric substance including air space offering a high resistance to the passage of current. That which is relied upon to insulate the conductor from other conductors or conducting parts or from ground.
The sharing of a common facility, such as a manhole, trench or pole, by two or more different kinds of utilities e. A removable seat used to facilitate work at an elevated position on rolling ladders in telecommunication centers. A platform consisting of separate planks which are laid across steel platform supports. The ends of the supports are engaged in the manhole cable racks. The act of communicating or signaling utilizing a frequency between 1 GH z gigahertz and GH z inclusively.
The nominal voltage of a system or circuit is the value assigned to a system or circuit of a given voltage class for the purpose of convenient designation. The actual voltage may vary above or below this value. A platform intended for use by a workman in splicing and maintenance operations in an elevated position adjacent to a pole.
It consists of a platform equipped at one end with a hinged chain binder for securing the platform to a pole. A brace from the pole to the underside of the platform is also provided. Any worker who by reason of his training and experience has demonstrated his ability to safely perform his duties. A tree worker who through related training and on-the-job experience is familar with the special techniques and hazards involved in line clearance.
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