What Does Arcing Mean?
Arcing, or electrical arcing, occurs when an electric current flows through the air from one conductive point to another. The heat and energy emitted by the arcing current can cause significant injury or death to anyone exposed to it.
Safeopedia Explains Arcing
Undesired arcing occurs when equipment is damaged in such a way that the current conducted through the equipment becomes uncontrolled, producing an arc fault. This causes the current to ionize the air, creating a conductive pathway through the air to another conductor - either a grounded object or person. As energy travels through the air, the resulting arc flash may produce temperatures of over 10,000oF (5537oC) capable of causing an electrical fire.
Not all instances of arcing are undesired. For example, arc welding, like TIG and MIG welding, relies on the purposeful and controlled production of electrical arcs.
Causes of Arcing
Arcing can be caused by numerous flaws in electrical systems including breaks in the insulation and the presence of impurities such as dust or rust. Major causes of electrical arcing include:
- Overload – When the circuits in a panel are overloaded, arcing can take place. In case of excess current flow, the circuit breakers may malfunction and allow the current to keep flowing instead of tripping, causing overheating and arcing.
- Faulty panels – Some electrical panels may have design flaws such as defective circuit breaker links. They may not be directly responsible for arcing but play a role and can be considered a safety hazard.
- Surroundings – Too many fuses in the box will allow additional current to flow through the circuit causing overheating and arcing. The presence of flammable material such as gasoline or thinner should never be kept near an electrical panel.
Replacing or refurbishing electrical equipment is necessary to prevent arcing, since degradation of electrical equipment can occur simply from its use.
Dangers of Electrical Arcing
Arcing, arc faults, and arc flashes are extremely dangerous as it concentrates current and voltage in a single place, releasing a massive amount of energy. Some of the dangers associated with arcing include:
- Heat generated can damage wire insulation, potentially resulting in electrical fires
- Generated heat can also cause a fire if the arc strikes a flammable material
- The extreme temperature of the arc can vaporize the conductors forming a considerable pressure of wave and sound resulting in damage to hearing
- Poisonous gasses capable of causing lung damage can be released from arcing
- Arcing can cause substantial damage to electrical equipment
Safety Requirements for Workers
The Occupational Safety and Health Administration (OSHA), National Fire Protection Association (NFPA), and other occupational safety organizations require electrical workers to wear personal protective equipment (PPE) that will not melt or burn upon contact with an arc flash.
In the United States, there are numerous standards designed to protect against arcing hazards. OSHA 1910.269 App E describes the requirement for protecting employees from dangers of arcing. The most recognized of these is the NFPA 70e standard, which OSHA relies upon to determine whether employers are providing workers with sufficient protection against electrical hazards.