Over the last 10 years, more than 45,000 workers have been injured by electrical hazards in the workplace. These injuries aren’t isolated to any particular industry or occupation. In fact, practically all members of the workforce are exposed to electrical hazards every day. Over half of all electrical fatalities are not even in traditional electrical fields. The victims are general laborers, drivers, maintenance workers, and managers – those least likely to be educated about the hazards. Most electrical accidents result from unsafe equipment, environments and work practices.

How do you protect your people? Start with an understanding of the fundamentals.

Before you can understand prevention techniques, you have to know what you’re working to prevent. There are three hazards that you need to know about.

Electrical shock

Electrical shock occurs when a person’s body completes the current path between two energized conductors of an electrical circuit or between an energized conductor and a grounded surface or object. Essentially, when there is a difference in potential from one part of the body to another current will flow. The degree of damage depends on the amount of current, path of the current through the body, duration of the current flow and body resistance. There is a common misconception that 120V – the lowest standard U.S. voltage – can’t hurt you. This couldn’t be further from the truth. All it takes is the right amount of current – which is a result of your body’s resistance (ohm’s law current=voltage/resistance) – to be fatal. The body’s resistance is highly variable depending on where the contact is made, the skin type, body composition and moisture levels. The effects of an electrical shock can vary from a slight tingle to immediate cardiac arrest. Often shock is accompanied by entry and exit burns and can cause falls from a height.

Bodily Effect	Gender	DC	60 Hz AC	10 kHz AC
Slight sensation at point(s) of contact	Men	1 mA	0.4 mA	7 mA
	Women	0.6 mA	0.3 mA	5 mA
Threshold of bodily perception	Men	5.2 mA	1.1 mA	12 mA
	Women	3.5 mA	0.7 mA	8 mA
Pain, with voluntary muscle control maintained	Men	62 mA	9 mA	55 mA
	Women	41 mA	6 mA	37 mA
Pain, with loss of voluntary muscle control	Men	76 mA	16 mA	75 mA
	Women	51 mA	10.5 mA	50 mA
Severe pain, difficulty breathing	Men	90 mA	23 mA	94 mA
	Women	60 mA	15 mA	63 mA
Heart fibrillation after 3 seconds typical	Men	500 mA	100 mA
	Women	500 mA	100 mA
Internal tissue burns, fatal or requires amputation	Men	501< mA	101< mA
	Women	501< mA	101< mA

Arc flash

An arc flash is the sudden release of electrical energy through the air when an arcing fault occurs between phase-to-phase, phase-to-neutral, or phase-to-ground conductors. An arc flash gives off thermal radiation (heat) and bright, intense light. Temperatures have been recorded as high as 35,000˚F. This extreme temperature melts and vaporizes metals and can ignite clothing and cause fatal burns as far as 10 feet away. The degree of the arc flash is determined by short circuit current and clearing time or arc duration – not voltage. It’s possible to generate greater arc energies from low voltages than from high voltages. An arc flash can have a variety of causes, including accidental contact with electrical systems, dropped tools, build up of conductive dust, corrosion, insulation breakdown, loose connections and improper work procedures or equipment utilization.

Arc blast

The vaporization and resulting expansion of metals causes an arc blast, which produces immense sound and pressure waves similar to a dynamite explosion. These pressure waves can rupture eardrums, collapse lungs, and propel workers across the room or cause them to fall from ladders. Molten metal droplets and fragments of surrounding equipment will be expelled at speeds up to 700 miles per hour causing blunt-force trauma, cuts and abrasions. In environments which contain explosive gases or combustible materials, even low-energy arcs can create violent explosions.

 

Beating the Odds

No single intervention strategy can eliminate electrical injuries at work. But accidents and fatalities can be avoided through a multi-faceted approach that includes engineering controls, organization of work, training and personal protective equipment. If only one major accident occurs, the associated costs of equipment damage, downtime, medical bills, insurance premium increases, workers compensation, attorney fees, accident investigation costs, retraining and bad publicity will far exceed what it would have cost to do it right in the first place.

All employees should be trained to be thoroughly familiar with the safety practices for their particular jobs. Training should address safety procedures for maintenance of specific electrical equipment, general electrical safety practices and associated standards in detail. Learn more about Training

Every good safety and health program provides measures to control electrical hazards. The responsibility for this program should be delegated to someone with a complete knowledge of electrical hazards, systems and work practices, and the appropriate standards. To develop your agenda, an electrical safety assessment will identify electrical safety hazards and compliance issues at your facility and provide an agenda for corrective action. Your electrical safety program and procedures should address employee exposure to specific hazards that exist in your workplace. Learn more about Safety Solutions

Analyze your power systems to identify conditions that cause instability and create hazardous workspaces. An arc flash hazard analysis defines flash protection boundaries and appropriate personal protective equipment for use by employees within the flash protection boundary. A protective device coordination study will reduce the amount of equipment affected by an overcurrent trip and the amount of incident energy a technician is subjected to when an arc flash occurs. A short circuit analysis will prevent extensive equipment damage and personnel injury because of underrated equipment in the event of a fault. Learn more about Power Studies.

Articles

Electrical Hazards Analysis
As the awareness of electrical hazards increase many are puzzled by phrases like "Limited", "Restricted", "Prohibited Approach Boundary", and "Flash Protection Boundary". This article will address the requirements to perform the "Shock Hazard Analysis" and the "Flash Hazard Analysis" required by the NFPA 70E-2004, Section 110.8(B)(1), "Electrical Hazard Analysis" as well as the "Blast Hazard Analysis" and personal protective equipment requirements.

Electrical PPE 101
Do you need to protect your workers from electrical hazards while working on energized equipment? How do you figure out what you need? The National Electrical Safety Code (for utilities) and the NFPA 70E (for industry) try to make selection easier. But, in the end, virtually every facility needs an Arc Flash Hazard Analysis done there is no way around it. BUT, if you have not completed your Arc Flash Hazard Analysis yet, what do you do? In this short document, we try to give you some guidance on how to select PPE in the meantime.

Electrical Safety and Maintenance Training
There is nothing more important to an electrical safety program than to have a staff of technicians who have been properly trained and who are qualified to do their jobs efficiently and safely.

Electrical Safety in Battery Maintenance and Testing
There are specific hazards associated with working on or near batteries and associated equipment. This article addresses the most common issues associated with performing maintenance and testing on various types of batteries, battery rooms and service areas.

Electrical Safety in Motor Maintenance and Testing
Working on motors has the same requirements as any other work that involves working on or near exposed energized and deenergized parts of electrical equipment operating at 50 volts or more. Learn what they are and how they affect motor maintenance and testing!

Electrical Safety in the Mining Industry
In resolving the issues in electrical safety in the mining industry, a path must be followed that will lead to a comprehensive analysis of the problems and hazards that exist or may exist and provide a quantified value to ensure the selection of appropriate personal protective equipment and clothing as well as safe work practices and procedures. Analysis of all three hazards: electrical shock, electrical arc flash, and electrical arc blast must be completed and steps taken to prevent injuries and fatalities.

Electricity - The Silent Killer
Electricity is often referred to as a "silent killer" because it cannot be tasted, seen, heard, or smelled. It is essentially invisible. Electricity has long been recognized as a serious workplace hazard, exposing employees to electrical shock, which can result in electrocution, serious burns, or falls that result in other injuries or even death.

Establishing an Electrical Safety Program
Establishing an effective electrical safety program is vital to the safety of employees. The employer is required to develop and implement an electrical safety program that addresses employee exposure to each specific hazard that exists. This program and the related training must be appropriate for all existing conditions and is required to be written, published and available to all employees who might be exposed to the hazards.

Protective Devices Maintenance and Arc Flash Hazard Implications
Preventative electrical maintenance is not only important for the reliability and integrity of electrical distribution systems, but also for the safety and protection of people. This paper addresses: Guides for maintenance and testing of circuit breakers and protective relays, failure statistics, and flash hazard implications.

Rail Transit Systems and Arc Flash
As population centers grow and expand into the suburbs these systems are experiencing pressures to expand. System operators have long been keenly aware of the need to keep the trains moving and the role reliable electricity plays in that mission. Trains that fail, in-transit,present significant safety and rider convenience issues, as well as expensive recovery efforts. This critical emphasis provides incentive for management to perform electrical procedures and repairs without taking down the power (de-energizing).

The Hazards of Electricity - Do You Know What They Are?
Electrical accidents are largely preventable through safe work practices. But, you must know the three hazards of electricity and their characteristics. If you can't STAY OUT OF THE CIRCUIT, know how to properly protect yourself!

 

Assessment Tests

AVO’s free assessment tests are designed to help you: determine the skill level of your technicians, test your subcontractors knowledge, help justify your training budget, or verify the skill level of a potential new hire. These tests are FREE and the scores are not recorded or used in any way. Use the latest version of Acrobat Flash – free download. Click the test title and a new browser window will open.

 

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