Follow the
standard for electrical safety in the workplace
An electrician is repairing heavy machinery. He’s wearing minimal protective gear of leather gloves and safety glasses. Something goes wrong — possibly a dead short to ground — and there’s an arc flash right in the electrician’s face. It melts his polyester shirt and trousers, severely burning his body.
It’s the type of tragic incident John Talik, of the UAW-Ford Health and Safety staff, knows could have been avoided if workplace safety standards had been followed.
There are two critical National Fire Protection Association (NFPA) standards when it comes to electrical safety: NFPA 70, the National Electrical Code (NEC), and the Electrical Safety Requirements for Employee Workplaces (NFPA 70E). NFPA 70E deals with many scenarios in industry that can cause injury or death, including arc flash.
“A lot of your burns are caused by arc flash, if not all of them,” Talik said.
The UAW’s Health and Safety Department keeps track of workplace injuries and fatalities to members and the list is painful to read. Some examples: A 27-year-old electrician was electrocuted in 1983 when working on a live circuit that was not locked out. A 56-year-old electrician was killed in 1993 after coming in contact with a live 440-volt circuit. A 42-year-old electrician was killed in 1983 after being burned in a buss duct electrical explosion.
Nearly 60 electricians have died in workplace incidents since 1973, according to UAW statistics. About half those fatalities were from electrocution, electrical explosions or fires.
In many cases, the deaths could have been avoided if proper safety precautions were followed.
Employers were supposed to start using the new NFPA 70E standard beginning this year. It identifies the requirements necessary for a workplace to be generally free from electrical hazards in a variety of conditions.
Procedures and training are key to preventing injuries and fatalities. The NFPA defines an electronically safe working condition as a state in which the conductor or circuit component to be worked on or near has been:
• Disconnected from energized parts (Note: Current drawings are very important to make sure that alternate electrical supplies are known.)
• Locked-out/tagged-out in accordance with established standards.
• Tested to ensure the absence of voltage.
• Grounded if necessary.
Additional safety measures must be taken when qualified workers need to work on or near equipment that is not in an electrically safe work condition. The NFPA has adopted procedures to provide safe work distances from hazardous arcs.
The table below provides approach distances to the exposed energized electrical conductors. The table helps establish acceptable distances for limited approach, restricted approach and prohibited approach.
Avoiding Flashover
The minimum air insulation distances required to avoid flashover are:
300 V and less — 0 ft., 0.03 in.
Over 300 V, not over 750 V — 0 ft., 0.07 in.
Over 750 V, not over 2 kV — 0 ft., 0.19 in.
Over 2 kV, not over 15 kV — 0 ft., 1.5 in.
Over 15 kV, not over 36 kV — 0 ft., 6.3 in.
Over 36 kV, not over 48.3 kV — 0 ft., 10.0 in.
Over 48.3 kV, not over 72.5 kV — 1 ft., 3.0 in.
Over 72.5 kV, not over 121 kV — 2 ft., 1.2 in.
Over 138 kV, not over 145 kV — 2 ft., 6.6 in.
Over 161 kV, not over 169 kV — 3 ft., 0.0 in.
Over 230 kV, not over 242 kV — 4 ft., 2.4 in.
The limited approach boundary defines the distance an unqualified person must stay from a live part. Under no circumstances can an unqualified person be permitted to cross the restricted approach boundary.
The restricted approach boundary is the area where a person must:
• Be qualified, including CPR training.
• Have an approved plan.
• Use personal protective equipment (PPE) approved for the condition.
• Position his or her body in a way that minimizes risk of inadvertent contact.
The prohibited approach boundary is the minimum approach distance to an exposed energized conductor or circuit part and is the closest point to prevent flashover. To cross this boundary and enter the prohibited space is considered the same as making contact with exposed energized conductors or circuit parts.
To cross this boundary a qualified person must:
• Have specific training to work on energized conductors or circuit parts.
• Have a documented plan justifying the need to work inside the prohibited approach boundary.
• Perform a risk analysis.
• Have the documented plan and the risk analysis approved by the site manager.
• Use PPE appropriate for working on exposed energized conductors or circuit parts rated for the voltage and energy level involved.
Talik said PPE can be anything from leather gloves and safety goggles to a full “moonsuit.” “It’s a totally covered suit with a face shield and a hood,” he added.
The code also calls for electricians to wear 100-percent cotton work clothes, not polyester. If an arc flash occurs, polyester will melt, causing serious burns.
Talik said training for electricians is under way, as is surveying all workplaces to determine safe distances and the level of PPE they must wear to service each piece of machinery. Employers are required to label all electrical devices to show safe distances and the PPE required.
Proper engineering controls greatly reduce risk and the need for some PPE. Current-limiting fuses and other devices can reduce the potential arc flash and arc-blast energy.
All electricians should read a copy of NFPA 70E. To order one, call NFPA at (800)-344-3555 or visit the NFPA Web site at www.nfpa.org.
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| This illustration shows the relationship between the respective boundaries and the part to be serviced. |
