Electrical Shocks, Arcs and Blasts
Anyone who has received even the most minor electrical shock is aware of the potential for serious injury or even death under certain circumstances.
This happens because the human nervous system is very fragile, explained David Frazelle, director of regulatory compliance, for ADM/Growmark, Decatur, IL.
The severity of an electrical shock and the amount of current flowing through the body depends on many factors: type of circuit, voltage, resistance of the body, amperage, what pathway the current takes through the body, and the duration of contact.
Frazelle was a speaker at a safety, health, and compliance seminar held in Overland Park, KS, in July and was there to present information on electrical safety-related work practices.
The seminar was jointly sponsored by the National Grain and Feed Association (NGFA/www.ngfa.org) and the Grain Elevator and Processing Society (GEAPS/www.geaps.com).
OSHA Standards
The Occupational Safety and Health Administration (OSHA/www.osha.gov) has set forth electrical safety standards that cover four major areas:
� Design safety standards for electrical systems.
� Safety-related work practices.
� Employee training.
� Safety requirements for Personal Protective Equipment (PPE).
The safety standards require that electrical-related equipment be free from recognized hazards that are likely to cause death or serious physical harm to employees. The three main hazards are electrical shock, electrical arc, and electrical blast.
Shocks, Arcs, and Blasts
Frazelle said electrical shock can cause severe damage to muscles and major organs. Every situation is different, but the damage happens because the human body has very little resistance to electrical current.
Electrical arcs cause about one-half of the serious electrical injuries each year; and injuries and fatalities can occur as far as 10 feet away.
An electrical arc may occur due to faulty equipment or circuits and is often caused unintentionally by the short-circuiting of conductors during troubleshooting or improper use of equipment.
An arc is extremely hot, as much as four times the temperature of the sun (36,000 degrees F). In comparison, irreparable cell death occurs at 203 degrees F. The heat from an arc will vaporize metals and ignite clothing.
Electrical blasts are caused by metal expanding from the extreme heat of an electrical arc. Blasts can cause fragmented or molten metal to become airborne, resulting in injuries or even death if you are not protected.
Approximately 136 people died last year from electrical accidents, Frazelle said. �Accidents don�t just happen,� he said. �There are always three possible factors: unsafe equipment, an unsafe workplace, and unsafe work performance.
�Unsafe acts by employees cause about 75% of the accidents. They fail to deenergize the system for repair, unintentionally use the wrong or defective tools, work too close to energized equipment, or engage in horseplay in the workplace,� he stated.
Hazardous Energy Control
Only qualified persons � those trained and familiar with the design, operation, and hazards surrounding electricity � should be allowed to work on or near it. A �qualified person� knows the technical side and the �safety-related work practices� mandated by OSHA, Frazelle said.
In general, OSHA requires that the electrical equipment be deenergized, tested, and locked out before service or maintenance is performed.
Specific details are outlined in OSHA�s Control of Hazardous Energy (Lockout/Tagout) Standard � 29 CFR 1910.147.
Equally, part 1910.333 covers additional requirements for electrical lockout/tagout that must also be implemented to control the additional hazards related to electrical systems.
The standard identifies the practices and procedures necessary to lock out and tag out machines and equipment. Employees must receive training in their role in the lockout/tagout program, and the standard mandates that periodic inspections be conducted to maintain or enhance the energy control program.
OSHA has determined that lockout/tagout is a more reliable means of deenergizing equipment than tagout alone.
In general, locking out and tagging is required prior to performing work on electrical systems. The only �exception to the rule� should be when equipment or electrical systems are to be worked �hot.�
According to OSHA, electrical systems must be deenergized, unless it would increase the hazard. These situations may include interrupting life support equipment, deactivating emergency alarm systems, ventilating systems, or testing electrical circuitry that must remain on for such testing.
Personal Protective Equipment
OSHA standard 1910.335 requires employees working in areas with potential electrical hazards to use personal protective equipment (PPE) that is appropriate for the specific parts of the body that need to be protected, Frazelle said.
This may include nonconductive head protection, adequate eye, face, hand, and foot protection. �Which parts of the body don�t you want to protect?� Frazelle questioned.
Alerting Techniques
Safety signs, symbols, or accident prevention tags must be used where necessary to warn employees about electrical hazards which may endanger them, Frazelle said.
The best safety plan begins with employee awareness, he said. �Your employees must understand the serious nature of electrical hazards and be properly trained.
�Provide proper PPE, and only allow qualified persons to work with or around electrical systems,� he said.
Written by Coreen Stevick, associate editor
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