Wired For Safety

Working with electricity can be dangerous.  Workers in the dental laboratory environment don’t typically work with electricity directly as do engineers and electricians, but they do work with electricity indirectly and may also be exposed to electrical hazards. OSHA recognizes electricity as a serious workplace hazard. Electrical injuries consist of four main types: electrocution (fatal), electric shock, burns and falls caused as a result of contact with electrical energy. OSHA’s electrical standards for general industry begin at 29 CFR 1910.301 (available at www.osha.gov).

Data obtained from the Bureau of Labor Statistics’ Annual Survey indicates that approximately 10 percent of all occupational fatalities are due to electrocutions. Data collected by the National Institute for Occupational Safety and Health (NIOSH) shows that fatalities due to electrocutions occur in a variety of ways. These include electrocution from workers contacting improperly grounded equipment, contact with overhead power lines, and use of damaged receptacles and connectors.

CHECKLIST FOR ELECTRICAL SAFETY

Here’s a checklist for you to use to survey your facility for electrical safety. These are some of the more common electrical safety issues that we observe in dental laboratories:

    *  Clear area in front of electrical panel so access is not impaired: this means three feet in front of the panels and one foot on the sides.
    * Ensure that Ground Fault Circuit Interrupters (GFCIs) are installed on all electrical outlets that are located within a close proximity to a water source. Six feet is the typical distance, but you should check with your local electrical codes to determine the correct distance. A GFCI is an electrical device, which protects personnel by detecting potentially hazardous ground faults and quickly disconnecting power from the circuit. A potentially dangerous ground fault is any amount of current above the level that may deliver a dangerous shock.
    * Extension cords may only be used on a temporary basis and are not a substitute for permanent wiring. When used on a temporary basis extension cords (flexible cords) must have a grounding conductor. They must be free of splices.
    * Electrical outlets that are located in an area that creates debris on the outlet (model department) should be protected in a manner to prevent the debris from entering the outlets.
    * Provide cover plates on all electrical outlets. If cover plates become broken, replace them immediately.
    * Mount power strips above counters, work surfaces, or floors.
    * Use chemical resistive electrical cords on equipment used in area where steam or acid may contact cords or outlets and cause corrosion of the outlet.
    * Cover outlets that are not in use that are located in close proximity to a water source, i.e. the plastic child-proofing type covers.
    * Do not overload electrical circuits by using multiple plug adapters.
    * The toaster oven being used to dry models is most likely UL rated for food preparation. If you can’t confirm that the UL rating covers your current usage of the equipment, you must replace the equipment with a commercial product rated for that purpose.
    * Ensure that portable electrical tools, appliances, and equipment are grounded.
    * Electrical installations in hazardous dust or vapor areas must meet the National Electrical Code (NEC).
    * Exposed wiring and cords with frayed or deteriorated insulation must be repaired or replaced.
    * Metal ladders are prohibited where the ladder or the person using the ladder could come in contact with energized parts of equipment, fixtures, or circuit conductors.
    *  All disconnecting switches and circuit breakers must be labeled to indicate their use or equipment served.
    * All unused openings in electrical closures and fittings must be closed with appropriate covers, plugs, or plates.
    * Electrical closures such as switches, receptacles, junction boxes must have tight-fitting covers or plates.

PREVENTIVE MEASURES

Use all receptacles and connectors only in accordance with the manufacturers' specifications, and the specific listing for the item as set forth by nationally recognized testing laboratories, such as Underwriter’s Laboratories (UL). Only use receptacles and connectors for applications for which they have been designed.

Develop and implement policies that address the proper use of receptacles and connectors.  Provide safety training that emphasizes awareness and recognition of electrical hazards associated with receptacles and connectors (i.e., broken receptacles and connectors, improper electrical connections, damaged cords, the importance of grounding, etc.). Stress the importance to workers of reporting immediately any damaged components so that they may be repaired. Enforce the safety policies and procedures.

Perform periodic inspections of all electrical system equipment and components to identify any electrical hazards present. Document the inspections and identify the hazards, then take appropriate corrective action immediately. Personnel using equipment should inspect it daily.

Use lockout/tagout procedures when servicing, maintaining or adjusting equipment.  OSHA Standard 29 CFR I910.147 should be consulted for the industry standards on lockout/tagout.  Equipment must be locked out and tagged out before any preventive maintenance or servicing is performed. Lockout is the process of removing the source of electrical power and installing a lock which prevents the power from being turned ON. Tagout is the process of placing a danger tag on the source of electrical power, which indicates that the equipment may not be operated until the danger tag is removed. JDTUnbound

Electrical Shock: It's not the voltage but the current that kills. The real measure of a shock's intensity lies in the amount of current (in milliamperes) forced through the body. Currents between 100 and 200 milliamperes (0.1 ampere and 0.2 ampere) are fatal. Anything in the neighborhood of 10 milliamperes (0.01) is capable of producing painful to severe shock.

First Aid for Electric Shock: Even though a person has stopped breathing he is not necessarily dead but is in immediate danger. Records show that seven out of 10 victims of electric shock were revived when artificial respiration was started in less than three minutes. After three minutes, the chances of revival decrease rapidly. Free the victim from contact with the electricity by turning off the supply switch or by removing the plug from its receptacle if a portable tool is being used. If the victim has suffered cardiac arrest or heart stoppage, then CPR may aid the person.

Do you have a question for Mary Borg? E-mail jdt@nadl.org.

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