When Is Wire Size An Electrical Hazard
Recognizing Hazards
Inadequate Wiring Hazards
OSHA inspects for inadequate wiring.
Inadequate or improper electrical wiring was i of OSHA'due south top 10 most commonly cited violations during 2016. An electric wiring hazard exists when:
- the wire is too minor for the electric current it will carry: could crusade a fire, or
- is not connected properly: could cause a shock hazard.
Ordinarily, the circuit breaker in a excursion is matched to the wire size. Nonetheless, in older wiring, co-operative lines to permanent ceiling light fixtures could be wired with a smaller estimate than the supply cable. Let'southward say a light fixture is replaced with another device that uses more current. The current chapters (ampacity) of the branch wire could exist exceeded. When a wire is too modest for the electric current information technology is supposed to carry, the wire volition heat upwards and could cause a fire.
When you utilize 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 exist the correct size for the circuit but not right for the smaller-gauge extension string. A tool plugged into the extension cord may employ more than electric current than the cord can handle without tripping the circuit breaker. The wire will overheat and could crusade a burn down.
The kind of metallic used as a usher can cause an electric gamble. Special care needs to exist taken with aluminum wire. Since it is more breakable 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 must recognize that inadequate wiring is a take a chance.
1. In which state of affairs beneath may an electric wiring fire hazard exist?
a. When the wire is not rated for the voltage information technology will conduct
b. When the wire is not the proper length for the current information technology will carry
c. When the wire is too small for the electric current it volition acquit
d. When the wire is to big and is inherently besides resistant
Exposed electrical parts.
Exposed Electrical Parts Hazards
Being "exposed" to electric parts occurs when a person tin inadvertently make contact with an energized conductor or circuit part.
- Wires and parts can be exposed if a embrace is removed from a wiring or billow box.
- The overhead wires coming into a home may exist exposed.
- Electrical terminals in motors, appliances, and electronic equipment may exist exposed.
- Older equipment, or equipment that is being service, may accept exposed electrical parts.
- If you contact exposed alive electrical parts, you will be shocked.
If you are possibly exposed to alive electrical parts in any of the situations above, earlier you work on the equipment, beginning turn off the power, if possible, or otherwise use lockout/tagout procedures or other hazard control measures to preclude or reduce exposure.
You must recognize that an exposed electrical component is a hazard.
Real-Life Scenario
Five workers were constructing a chain-link fence in front of a house, straight below a seven,200-volt energized power line. As they prepared to install 21-pes sections of metallic peak track on the fence, one of the workers picked up a section of track and held it up vertically. The track contacted the 7,200-volt line, and the worker was electrocuted. Following inspection, OSHA determined that the employee who was killed never received any safety training from his employer and no specific instruction on how to avoid the hazards associated with overhead power lines. In this case, the visitor failed to obey these regulations:
2. What precautions should y'all accept when working around old motors, appliances, and electric equipment to eliminate or reduce exposure to live electrical parts?
a. First, turn off the power
b. Test high-voltage with a meter
c. Post alert sign
d. Utilise the spark examination for voltage
Approach Boundaries
The take chances from exposed live parts depends on your distance from the parts. Iii "boundaries" are key to protecting yourself from electric shock and 1 to protect you from arc flashes or blasts. These boundaries are set by the National Fire Protection Association (NFPA 70E-2015).
The risk from exposed live parts depends on your distance from the parts.
- The Restricted Approach Boundary. This is the closest boundary to exposed alive parts. Only a Qualified Person wearing appropriate PPE, as adamant by the Stupor Adventure Assessment, may enter. The Qualified Person must as well have an Energized Electrical Work Permit (EEWP). When you're this close, if you movement the wrong way, you and your tools could bear upon live parts.
- The Limited Arroyo Boundary. An Unqualified Person may enter this surface area, just only if continuously supervised and escorted by a Qualified Person, and advised of potential hazards. Both persons must wearable appropriate PPE every bit determined by the Shock Risk Assessment. A qualified person is someone who has demonstrated the skills and knowledge on the hazards and on the construction and operation of equipment involved in a task.
- The Arc Flash Boundary. Only Persons wearing appropriate PPE for the Arc Flash Purlieus, every bit determined by an Arc Flash Risk Assessment, may enter.
three. Merely an electrical Qualified Person wearing appropriate PPE, equally determined by the Shock Risk Assessment, may enter _____.
a. the Arc Blast Zone
b. the Arc Flash Boundary
c. the Express Approach Boundary
d. the Restricted Approach Boundary
Overload Hazards
Watch out for overload hazards.
Overloads in an electrical system are hazardous considering they can produce heat or arcing. Wires and other components in an electrical organization or excursion accept a maximum corporeality of electric current they tin conduct safely. If too many devices are plugged into a circuit, the electrical current will heat the wires to a very high temperature. If a tool uses too much current, the wires will heat up.
The temperature of the wires can be high plenty to cause a burn down. If their insulation melts, arcing may occur. Arcing can cause a burn down in the area where the overload exists, even inside a wall.
To preclude too much electric current in a excursion, a excursion 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 role of the fuse melts, opening the circuit. Both breakers and fuses practice the aforementioned 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.
Y'all must recognize a circuit with improper overcurrent protection devices - or 1 with no overcurrent protection devices at all - is a hazard.
Overcurrent protection devices are built into the wiring of some electrical motors, tools, and electronic devices. For example, if a tool draws likewise much current or if it overheats, the electric current will be shut off from within the device itself. Damaged tools tin can overheat and cause a fire.
You lot must recognize that a damaged tool is a gamble.
iv. Which of the following is Truthful about circuit breakers and fuses?
a. Circuit breakers are more reliable than fuses
b. Circuit breakers will melt and fuses will open
c. Both circuit breakers and fuses open the excursion
d. Fuses must always be located near a circuit breaker
Inadequate insulation caused a short and fire.
Defective Insulation Hazards
Insulation that is defective or inadequate is an electric risk. Usually, a plastic or rubber covering insulates wires. Insulation prevents conductors from coming in contact with each other and with people.
Extension cords: Extension cords may have damaged insulation. Sometimes the insulation within an electrical tool or appliance is damaged. When insulation is damaged, exposed metal parts may become energized if a live wire inside touches them.
Tools: Electric hand tools that are old, damaged, or misused may have damaged insulation inside. If you touch damaged power tools or other equipment, you will receive a shock. You are more likely to receive a shock if the tool is not grounded or double-insulated. Double-insulated tools have ii insulation barriers and no exposed metal parts.
You must recognize that defective insulation is a hazard.
5. While working with electrical manus tools, when are yous more likely to receive a stupor?
a. If the tool is not grounded or double-insulated
b. If the tool was made prior to 1989
c. When the tool has synthetic insulation
d. When a tool is used while wearing leather gloves
Next Section
Improper Grounding Hazards
Proper grounding is important.
When an electric system is non grounded properly, a hazard exists because unwanted voltage cannot be safely eliminated. The near common OSHA electrical violation is improper grounding of equipment and circuitry. The metal parts of an electrical wiring system that we touch (switch plates, ceiling low-cal fixtures, conduit, etc.) should be grounded and at 0 volts. If the arrangement is not grounded properly, these parts may become energized. Metallic parts of motors, appliances, or electronics that are plugged into improperly grounded circuits may exist energized. If there is no safe path to footing for fault currents, exposed metallic parts in damaged appliances can become energized.
Extension cords may non provide a continuous path to ground because of a broken ground wire or plug. If you contact a lacking electric device that is non grounded (or grounded improperly), you will be shocked.
You must recognize an improperly grounded electric organization is a chance.
half-dozen. What is the most common OSHA electrical violation?
a. Defective power tools
b. Failure to use GFCIs on worksites
c. Use of three-prong plugs with ability tools
d. Improper grounding of equipment and circuitry
Adjacent Section
Footing Mistake Circuit Interrupters (GFCI)
A ground mistake excursion interrupter, or GFCI, is an inexpensive life-saver. GFCIs detect any divergence in current betwixt the 2 circuit wires (the black wires and white wires). This deviation in current could happen when electrical equipment is not working correctly, causing leakage current. If leakage current (a ground error) is detected in a GFCI-protected circuit, the GFCI switches off the current in the circuit, protecting you from a unsafe shock.
More important points to think:
- GFCIs are set up at about 5 mA and are designed to protect workers from electrocution.
- GFCIs notice the loss of electric current resulting from leakage through a person who is beginning to be shocked. If this situation occurs, the GFCI switches off the current in the excursion.
- GFCIs are different from circuit breakers considering they detect leakage currents rather than overloads.
Circuits with missing, damaged, or improperly wired GFCIs may allow you to be shocked.
You demand to recognize that a excursion improperly protected past a GFCI is a hazard.
seven. Ground Fault Excursion Interrupters (GFCIs) detect the loss of current resulting from _____.
a. a disconnected basis wire in the circuit
b. leakage through a person who is beginning to be shocked
c. short circuits directly to basis
d. an open circuit due to a person non properly grounded
Overhead Powerline Hazards
Working virtually overhead power lines is very unsafe.
Most people do non 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 exist especially enlightened of the dangers of overhead lines.
In the by, lxxx% of all lineman deaths were caused past contacting a alive wire with a bare hand. Due to such incidents, all linemen at present vesture special rubber gloves that protect them up to 34,500 volts. Today, most electrocutions involving overhead powerlines are caused by failure to maintain proper work distances.
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 yous do not maintain required clearance distances from powerlines, yous 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 virtually over-caput powerlines. We'll talk more about this topic in the next department.
viii. In the past, what has been the major cause of all lineman deaths due to electrocution?
a. Touching the live wire with a bare hand
b. Falling beyond a live wire at pinnacle
c. Unintentionally contacting some part of the body with a live wire
d. Completing the circuit between ii live wires
Minimum Arroyo Distances
Minimum Approach Distance.
Altitude Correction Factor for Minimum Arroyo Distances. Minimum arroyo distances ensure that workers do not approach or have any conductive object closer to the energized parts. If the piece of work is performed at elevations greater than iii,000 ft (900m) in a higher place hateful sea level, the minimum arroyo distance must be determined past multiplying the distances by the correction factor corresponding to the distance at which the work is performed.
Depending on the voltage of the line, a worker or a conductive object, must keep the minimum distance specified below between them and any energized role of the power line.
For more information on minimum approach distances and evaluating piece of work zones, run across Oregon OSHA's Fact Sail on Ability Line Safety.
See 29 CFR 1910.269 Tables R-3 through R-9 for more than data on calculating approach distances.
9. Which of the factors beneath will increase the safe altitude (phase to ground exposure) from a loftier voltage line?
a. Decrease in humidity
b. Increase in humidity
c. Subtract in distance
d. Increase in altitude
Next Section
General Indicators of Electrical Hazards
Where there is smoke, in that location is fire.
There are a number of general situations and conditions in the workplace that indicate electric hazards:
- Tripped circuit breakers and blown fuses show that too much electric current is flowing in a circuit. This status could be due to several factors, such as malfunctioning equipment or a short betwixt conductors. Yous need to determine the cause in order to control the chance.
- An electric tool, appliance, wire, or connection that feels warm may indicate too much electric current in the circuit or equipment. You lot need to evaluate the situation and determine your risk.
- An extension cord that feels warm may indicate besides much current for the wire size of the cord. You must decide when activity needs to be taken.
- A cable, fuse box, or junction box that feels warm may indicate likewise much current in the circuits.
- A burning odor may signal overheated insulation.
- Worn, frayed, or damaged insulation around whatsoever wire or other conductor is an electrical hazard because the conductors could be exposed. Contact with an exposed wire could crusade a shock. Damaged insulation could cause a short, leading to arcing or a fire. Inspect all insulation for scrapes and breaks. You demand to evaluate the seriousness of whatever damage you find and decide how to deal with the hazard.
- A GFCI that trips indicates at that place is electric current leakage from the circuit. Outset, you lot must decide the likely crusade of the leakage by recognizing any contributing hazards. Then, you must decide what action needs to be taken.
x. Tripped excursion breakers and blown fuses prove that _____.
a. the speed of the current in the circuit is too fast
b. the resistance in the excursion has increased
c. there has been a fasten in voltage
d. likewise much electric current is flowing in a circuit
Check your Work
Read the material in each section to find the correct answer to each quiz question. Afterward answering all the questions, click on the "Check Quiz Answers" button to grade your quiz and come across your score. You will receive a message if you lot forgot to answer i of the questions. Later on clicking the push, the questions you missed will exist listed beneath. You tin can correct any missed questions and cheque your answers over again.
Video
Video
This is an excellent electrical presentation past Rodney Sherman given at Holy Cantankerous Energy. It volition make a believer out of you.
When Is Wire Size An Electrical Hazard,
Source: https://www.oshatrain.org/courses/mods/615m2.html
Posted by: greenvory1971.blogspot.com
0 Response to "When Is Wire Size An Electrical Hazard"
Post a Comment