HD Electric Products

More Information

Home » Library / Archives » Focus on Safety Equipment & Clothing

Focus on Safety Equipment & Clothing

Power Delivery Product News, September/October 1998
Software Helps Protect Workers from Electrical Arcs

Safety is extremely important to utilities whether it is climbing to the top of utility poles or handling power lines. To prevent injury to utility workers, utilities provide safety equipment, including gloves, proper tools and fall prevention equipment. To protect workers from dangerous electrical arcs, utilities also have guidelines on protective clothing.

The sudden discharge of electricity, causing an electrical arc, can cause clothing to ignite without warning. The hazard can be prevented with proper planning and analysis of clothing types, weight and distance from the potential hazard. OSHA has established standards to assist utilities in determining their clothing needs.

OSHA Requirements

According to a Department of Energy (DOE) OSHA Technical Reference, arc burns, caused by electric arcs, are heat burns similar to burns from high-temperature sources. The temperatures generated by electric arcs can melt material nearby, vaporize metal in close vicinity and burn flesh and ignite clothing at distances up to 10 feet.

To assist employers in protecting their employees, OSHA regulations have made it necessary for employers to ensure that the clothing worn by workers exposed to electrical arcs must not contribute to the extent of an injury. OSHA requires utilities and industries to show compliance with such regulations if there is an accident.

According to OSHA policy, the types of clothing that are acceptable under the rule are all flame-resistant and flame-retardant (FR) clothing under all conditions. This includes FR cotton and wool, as well as Nomex and PBI/Kevlar. Clothing made from 11-ounce cotton is acceptable for employees exposed to electric arcs that are comparable to a 3800-ampere, 12-inch arc lasting for 1/6 second at a distance of 12 inches from the employee. It is the responsibility of the employer to determine proper clothing for the particular circumstances that its employees may be exposed to.

Clothing Analysis Tool

To help utilities determine the proper clothing, HD Electric Company has released an electric arc hazard assessment software program, ArcPro v.2. It is a software program developed to calculate the thermal parameters of electrical arcs and to aid in the selection of protective clothing by defining the arc hazard for workers who may be accidentally exposed to electrical arcs. The user can then specify clothing that will withstand the level of predicted arc hazards.

ArcPro v.2 is designed to provide the user with a method to calculate heat exposure regarding total heat flux and heat energy on a surface at various distances from an electrical arc. The software is used to predict the potential arc hazard in a particular work environment and thus it can help in choosing the appropriate protective clothing.

The computer program is based on a state-of-the-art electrical arc model. Temperature-dependent gas properties, the electrode materials and configuration are taken into account in the model.

According to C. Thomas Baker, safety consultant at Detroit Edison, ArcPro is an extremely user friendly program to use. Coming from a non-technical background, Baker believes that the program input windows and results are easy to learn and analyze.

Most of the calculation results are provided in numeric and graphic forms on the screen and can be sent to a printer. Users provide several input parameters describing the arc and then simply click on the menu items to run calculations and view results. The typical input to the program includes arc current, arcing gap and distance from the arc. The typical output from the computer program includes the total energy available, the heat and heat flux at any location around the arc, illustration of the zone in which a particular fabric will ignite, radiated heat flux, convected heat flux, clothing database, second degree burn criteria and waveforms of the arc current, arc voltage and arc diameter.

At Detroit Edison, Baker uses the program for hazard analysis of FR clothing. According to Baker, the 1998 update to the program has been extremely helpful. The new version includes clothing updates that have been useful in Detroit Edison's hazard analysis operations.

Protection from any hazard is important to all utility workers. Analysis of the hazard before actually going out in the field is critical and, according to HD Electric Company, ArcPro provides this analysis.

Click here to visit the ArcPro Arc Analysis Software product page

Click here to return to Library/Archive page

Back | Top