Electrocution Hazards.
Electrical power installers make up the greatest percentage
of deaths caused by electrical contact, then earth drillers, helpers,
electricians, ironworkers, welders, and roofers.
Types of electrocutions.
- Overhead power lines.
- Machinery and appliances.
- Electrical equipment and wiring
- Energized objects
The leading cause of these electrocutions.
- Failure to maintain a safe distance from an energized power source.
- Failure to lock and tag out an energized power source.
- Failure to use a ground fault circuit interrupter.
Electrical shock.
Electrical shock is received when current passes through the
body. Severity of the sock depends on 3 things. The passing of current through
the body, the amount of current flowing through the body, and the length of
time the body in the circuit. Most fetal electric shocks travel through the
heart.
Electricity’s effect on the body.
1 milliamp = shock is hardly noticeable.
5 milliamps = slight shock, not typically painful most can
control muscles.
6 to 30 milliamps = painful shocks, loss of muscular control
lost.
50 to 150 milliamps = extremely painful shock, breathing
stops, severe muscular contractions.
Electrical hazard by category.
1-Bruns.
From Electricity are one of three types.
Electrical.
Electrical burns result from heat generated by the flow of
electric current through the body.
Arcl flash.
Arcl flash burns are high temperature burns caused by an
electric or explosions.
Thermal contact.
Thermal contact burns occur when skin comes in contact with
overheated electric equipment.
2- Electrocution.
Electrocution mean death caused by electricity and it is
always fatal. Electrocution happen when a human is exposed to a lethal amount
of electrical energy.
3- Shock.
Shock result when the body becomes part of the electrical
circuit. Electrical shock is defined as reflex response to the passage of
electric current through the body.
4- Arc flash.
Arc flash is the sudden release of electrical energy
through the air when a high voltage gap exists and there is breakdown between
conductors.
Arc flash gives off thermal radiation (heat) and bright
intense light that can cause burns. Arc flash can reach temperature as high as
35000 degrees and can also produce considerable pressure waves by rapidly
heating the air creating a blast. Arc flash can be spontaneous or result from
inadvertently bridging electrical contacts with a conducting object. Other
causes may include dropped tools or the build up of conductive dust or
corrosion.
5- Fire.
Most of electrical distribution fires result from problem
with fixed wiring such as faulty electrical outlets and old wiring. Problem
with cords (such as extension and appliance cord), plugs, receptacles, and
switches also cause fires.
6- Explosions.
An explosion can occur when electricity ignites an explosive
mixture of materials.
Major electrocution hazards leading cause of death.
- Contact with overheated and burned power line.
- Contact energized sources.
- Improper use of extension and flexible cord.
OSHA standard requirements.
Specify minimum safe distance during operation of electric.
Must be 10 ft away from all overheated power.
If the line voltage is 750000 volts add 4 inches for every
increase of 10000 volts.
Minimum clearance distance to be:
- Up to 50 volts = 10 ft
- 50 to 200 volts = 15 ft
- 200 to 350 volts = 20 ft
- 350 to 500 volts = 25 ft
- 500 to 750 volts = 35 ft
- 750 to 1000 volts = 45 ft
- Over 1000 volts = as established by the power line owner/ operator or registered professional engineer.
Underground electrical hazard.
Temporary power system must be checked for polarity, ground
continuity, and ground resistance.
Competence person inspection required for electrical cord
sets, temporary receptacles, and equipment connected by cord and plug.
Only qualified employees should perform work or adjacent to
energized control panels.
The vertical clearance
of temporary wiring for circuits carrying 600 volts or less should be:
- 10 ft above finished grade, sidewalks, or from any platform.
- 12 ft over areas other than public street, alleys, roads and driveways, subject to vehicular traffic other than truck traffic.
- 15 ft over areas other than public streets, alley, roads, and driveways, subject to truck traffic.
- 18 ft over public streets, alleys, roads, and driveways.
Inspections.
Inspection extension cords and tools.
Worker need to inspect extension cord prior to their use for
cuts or abrasion, damaged insulation, and strain relief.
Power tools / equipment.
Never carry a tool by the cord. Never yank the cord from
heat, oil, and sharp edges. Disconnect when not in use and when changing
accessories such as blades and bits. Avoid accidental starting, do not hold
fingers on the switch button while carrying a plugged in tool.
Example for misused tools.
Using multi-receptacle boxes designed to be mounted by
fitting thew with power cord and placing them on floor.
Fabricating extension cords with RomEx wire.
Using equipment outdoor that is labeled for use only in dry,
indoor location.
Controlling hazards energies.
Lockout/tagout.
A lockout/tagout is essential safety producer that protects
worker from injury while working on or near electrical circuit and equipment.
Prevent contact with operating equipment parts such as blades, gear, shafts,
etc. prevent the unexpected release of hazardous gasses, fluids, or solid
matter in the area where worker is present.
Lockout mean the practice of using locks to prevent unwanted
activation of mechanical or electrical equipment.
Tagout mean the practice of using tag with locks to increase
visibility and awareness that the lock is protecting someone’s life.
Basic specification worker in lockout/tagout.
Authorized person.
Someone who lockout or tagout machines or equipment in order
to performing serving or maintenance.
Affected person.
Someone who operates equipment on which maintenance is
performed under lockout/tagout or an employee that works in an area where
serving and maintenance is being performed.
Lockout/tagout checklist.
- Identify all sources of hazardous energy for the equipment or circuits in questions.
- Identify backup energy source such as generator battery.
- Identify all shut off for each energy source found.
- Notify all personnel that equipment and circuitry must be shut off, lockout, and tagout.
- Shut off energy sources and lock control in the off position.
- Each worker must apply an individual lock and the individual keys kept with each worker .
- Test the equipment and circuitry to ensure zero energy exists. This must be done by a qualified person.
Five major causes of lockout/tagout injuries.
1-
accidental restarting of equipment- 50%.
2- Failure to release residual
energy- 50 %.
3- Failure to disconnect from
power source- 25 %.
4- Failure to clear work area
before restarting- 10 %.
5- Failure to stop equipment- 5 %.
How can I protect myself from electrocution hazards?
- Use ground fault circuit interrupters(GFC)
- Maintain a safe distance from overhead power line.
- Inspect portable tools and extension cords.
- Use power tools and equipment as designed.
- Follow lockout/tagout procedures.
PPE for electrical work.
Foot protection.
Will marked EH (electrical hazard)
and must be dry.
Head protection.
Must be insulated-nonconductive
hard hat. Class B or E. does not store anything in the top of your hat.
Hand protection.
Must be rubber insulating gloves,
classified by level of voltage and protection they provide. should always be
worn over rubber insulating gloves to provide the mechanical protection needed
against cut, abrasions, and punctures.
Steps should be taken in case of an electrical fire.
- Active fire alarm system.
- Alert everyone in the area to evacuate.
- Never use a type A water extinguisher or water to extinguish an electrical fire.
- If trained use Co2 or dry chemical fire extinguisher
- Remain a safe distance away and wait for the fire department to arrive.
Steps should be taken if a person is being shocked.
- Do not touch him.
- Try to safely turn off the source of power.
- Using not conductive materials to move the person from the electrical source.
Employer requirement.
Three majors’ way employers should
be controlling power line hazards:
1- maintaining a safe distance
from lines.
2- having the power company
de-energized and ground the power line with a power company representative at
the site.
3- having the power company
install insulated sleeves over power lines.
Also, the employer should train
workers on power lines hazards and available protective measures.
The employer responsibility to
provide either ground fault circuit on construction site for receptable outlet
in use and not a part from the permanent wiring of the building, or a schedule
and recorded assured equipment grounding conductor program on construction
sites covering all cord sets, receptacles which are not part of permanent
wiring of the building.
Also, employer responsibility for
provide approved ground fault circuit interrupters for all 120 Volt, single
phase, 12 and 20 Ampere receptacle outlet.