Can an MSDS Spark Electrical Safety?

Feb. 3, 2004
While given little thought in many workplaces, electrical energy represents a potentially lethal hazard. To help your employees understand this invisible hazard, you can use a familiar tool the material safety data sheet.

An electrical safety material safety data sheet or "ES MSDS" is a communication tool that can characterize electrical hazards using a familiar format often seen in training for chemical safety.

For employers, the ES MSDS provides a vehicle for addressing risks from electrical hazards using strategies in place for toxic exposures managed under federally mandated hazard communication programs.

Most workers use electricity every day, which means employers face a formidable educational challenge. Many employees working on or near electrical sources require specific task-related training, in particular in craft and trades activities. However, others do not fall under obligations for routine electrical safety meetings or compliance with electrical codes and standards. Whether for employees in a trade or an office, an ES MSDS is an efficient way to alert them to the specifics of electricity that can lead to trauma or death.

An ES MSDS can be developed as part of an employer's general safety program, with the information here serving as a basic reference. The ES MSDS can also be incorporated into a company's electrical safety program designed in compliance with NFPA 70E Standard for Electrical Safety Requirements for Employee Workplaces, 2000 Edition. Finally, the information in an ES MSDS complements the installation labeling requirements of NFPA 70 National Electrical Code (NEC), 2002 Edition.

Electrical safety education presents unique challenges. First, as a hazard, electricity is silent, odorless and invisible, like oxygen.

Second, the use of electricity is commonly viewed as a safe experience. Every time a light is switched on, or a mouse points a cursor on a video display, electrons flow while injury or damage rarely, if ever, occur. There are numerous daily instances that reinforce the experiential learning that electricity is essential but not noticeable in the completion of work.

This again is similar to our collective knowledge of oxygen. Most people understand life depends on the presence and flow of oxygen in our bodies and environment. However, too much oxygen can be toxic and explosive. Similarly, electricity can be toxic and explosive. Advances in occupational electrical safety have reduced injuries and deaths from working on or near electrically energized installations and equipment. Yet, people continue to be harmed by occupational electrical sources.

According to published data from James Cawley and Gerald Homce at the National Institute for Occupational Safety and Health (NIOSH) Pittsburgh Research Laboratory, from 1992-1998, there were 2,268 occupational electrical fatalities, with 1,225 attributed to other than overhead power line sources. In the same period, 32,309 nonfatal occupational electrical incidents were reported, resulting in at least one day away from work; 31,089 of these were not associated with overhead power line sources.

Based on these figures, on average, there are about one electrical fatality and 12 electrical injuries occurring each day in U.S. workplaces.

Energy Damage

The analogy between a physical hazard like electricity and a chemical like oxygen rests on the recognition that these exposures are fundamentally electrochemical in nature. It is not common to think of this analogy. Just as when a chemical's containment is breached, when power frequency (50-60 Hz) electrical energy's containment within its intended conducting path is unintentionally faulted by installation failure or human error, the electrical energy's interaction with the surrounding environment can lead to oxidation-reduction reaction, combustion, thermo-acoustic gas expansion and plasma ignition. Electro-mechanical effects can accompany the electro-chemical phenomena, creating further destructive results.

Since William Haddon's pioneering publications in the mid-20th century, safety researchers have understood that all occupational injury fatalities share an energy damage process. In a fatality, the occupational incident has resulted in sufficient energy transfer, in such ways and amounts, from the work environment to the person (via electrical, mechanical, radiation, acoustic or pressure exposure) to create an unrecoverable destructive effect on the body. Non-fatal incidents result from sub-lethal exposures.

An electrical event can happen with the simplest act for example, a screwdriver slipping in an energized panel. Such a discrete failure can be associated with catastrophic results.

Prior to the start of an electrical event, electricity flows from a power source, usually a public utility connection, through a facility's electrical system via metallic conductors into the installation. At an electrical event's start, there is an electro-chemical conversion or energy transformation that can be recognized as the event's initiation.

Once energy transformation occurs, the energy flowing into the event is no longer necessarily contained or held in the installation's metallic conductors. Electro-mechanical effects can follow. Transformed energy can "transfer" or release into the installation's space.

When the energy transfer occurs into space that is also occupied by a worker, worker injury or death may occur, depending on the magnitude, duration and quality of the energy transfer. As a rough rule, for power frequency (50/60 Hz) electrical energy, the destructive potential of 1 megawatt (MW) is approximately equal to that of one stick of dynamite.

ES MSDS Elements

An electrical safety MSDS communicates that electricity is toxic to humans. The language of the electrical industry can be translated into MSDS terms:

Chemical Nature and Ingredients. The chemical nature of electricity is electrons, the charge carriers in metallic conductors. The ingredients are power frequency (50/60 Hz) electricity as electrical energy flowing in metallic conductors, including conductors composed of copper, aluminum, iron and other metals.

Flash Point. The MSDS chemical parameter of "flash point" can be recognized as the dielectric breakdown characteristic of the power frequency electrical source.

In safety practice, as a rough rule, equipment is designed to allow 1 inch of space for each 1,000 V electrical force, to reduce the chance for "flash" or electrical arcing. Used as a "space break" or "air cushion," a distant gap between surfaces of conductors in installations uses the poor electrical conductance physical parameter of environmental air to reduce the likelihood of electrical arcing. Worker training about distant gaps are built into the concepts of flash, prohibited and permitted boundaries during electrical work.

Explosivity. Just as too much oxygen concentrated into a very small space can lead to an explosion, concentrating power delivery into a small geometric space can exceed the spatial and temporal limits of performance of the equipment. The explosivity parameter of power frequency electrical energy is characterized in electrical terms by the power density in the installation. More power concentrated in smaller installations over fractions of time (nano to milli seconds) increases the explosion hazard.

As a practical matter, electrical codes guide the safe design and building of electrical installation by indicating the ratings of equipment. Typically, these ratings are supported by nationally recognized laboratory (N.L.) testing of the installations. As well, this is the reason that electrical inspectors insist on the installation of "rated and tested" equipment.

Threshold Limit. The toxicity threshold limit of power frequency electrical energy exposure is a fractional amount of current flowing from a voltage source that can be of less than 110 V electrical force. (Note: the Occupational Safety and Health Administration (OSHA) requires safe electrical work practices for exposures of 50 V electrical force.)

The threshold limit concept is incorporated in the electrical industry via the engineering and deployment of ground fault current interrupters, or GFCI devices, where there is a risk of power frequency electrical current exposure.

These electrical devices are set to interrupt the flow of electrical current between 3-6 one-thousandths of 1 ampere, to avoid the potentially fatal exposure of people who might be working with an electrical tool or near an electrical source.

Lethal Dose. The lethal dose of power frequency electrical energy is typically considered to be the current exposure that interferes with the human body's electrical conduction patterns in the heart. As a result of exposure to less than one-tenth of 1 ampere current flow (0.1 A) at 110 V electrical force, electrical conduction in the heart can be disrupted, resulting in inefficient blood flow through the heart, with subsequent poor circulation to the brain and other vital organs. Without intervention, death can be reasonably expected in this situation, hence the assignment of this exposure as potentially lethal.

Flammability Warning. Electrical sources are extremely flammable. This truth lies behind the historical evolution of the National Electrical Code as a document published by the National Fire Protection Association (NFPA). An ES MSDS can build on the communications approach popularized through codes and standards published through NFPA consensus processes by using a NFPA hazard rating scheme.

For example, power frequency electrical energy is rated a level 4 flammability hazard, or the highest level assignable.

Reactivity Warning. The reactivity of electrical installations can be characterized as "may be explosive if shocked, heated, under confinement or mixed with water." Using an NFPA rating scheme, this would be level 3 reactivity, where "0" is "not reactive with water" and "4" is "reactive at room temperature."

Health Hazards. Power frequency electrical energy exposure may be fatal on short exposure. Specialized protective equipment is required when working on or near energized installations. Using a NFPA rating scheme, electrical hazards deserve a level 4 or highest hazard assignment. Note that a "0" would connote "no unusual hazard."

Control Measures and Precautions for Safe Handling. As a worksite develops its ES MSDS documentation, specific design, engineering, policies, procedures and containment strategies, including barrier protection and personal protective equipment, can be incorporated. An ES MSDS communication tool provides a focus and method to organize the diverse activities necessary to integrate comprehensive electrical hazard management.

Additional Information for Post-Incident Planning. The MSDS format has a space for additional information for post-incident planning.

Specific information items an employer may wish to include are:

  • Local utility supplier of electrical energy
  • Local electrical contractor or onsite electrical service provider
  • Local emergency response contact (e.g., 911) for fire service and medical first response
  • Triage location and evacuation sites
  • Designated Emergency Medical System (EMS) American Burn Association (ABA) certified burn center.

Specific first responder guidance should conform to the ABA recommendations. Training on electrical event first response needs to include:

1. Procedures for how to disconnect and de-energize the event source.

2. How to stabilize the victim's cervical spine prior to cardiopulmonary resuscitation.

3. How to initiate CPR.

Questions for Electrical Event Survivor Care Givers. When a responder brings an electrical event survivor into the medical care delivery system, they can organize the workplace specific information which may be obvious from their triage and transport activities in response to 16 questions about the electrical incident, shown in Table 1. In providing organized site-specific descriptions of an electrical event survivor's exposure, first responders can directly influence the medical care the patient receives in the critical care setting.

In conclusion, an ES MSDS can optimize education and communication about electrical hazards using terms familiar from chemical safety training.

By creating greater hazard awareness, an ES MSDS can take electrical safety management in the workplace to the next level, so that in the future, fewer people may be injured or killed while working on or near an electrical source.

Mary Capelli-Schellpfeffer, MD, MPA, is a principal with CapSchell Inc., a Chicago-based research and consulting business dedicated to the goal of preventing injury and death at work. For more information, contact (773) 960-5802 or [email protected].

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