Ensure Electrical Safety by Following New Arc Flash Guidelines
Written by Jack Rubinger
It's time to revisit Arc Flash.
To ensure standards remain relevant, National Fire Protection Agency (NFPA) updates their 70E guide every three years and 2012 falls on one of those years. In the 2009 version of the NFPA 70E, standards for electrical equipment only required arc flash labels to display available incident energy or required level of PPE. NFPA did not single out specific pieces of electrical equipment for customized labeling. In fact, electrical equipment labeling has never been a well-defined standard or code by NFPA until now.
NFPA sets the majority of safety standards for electrical work in the U.S. Their 70E guide is used throughout America and is the standard for safe electrical work practices.
In current NFPA 70E standards, labels used on specific electrical equipment must now display specific details about a hazard. Many facilities may lack required arc flash labels on hundreds of pieces of electrical equipment - which could compromise the safety of workers and others while also putting them in violation.
Let's focus on the new 70E labeling changes. Arc flash labels are now required on:
- Industrial Control Panels
- Panel Boards
- Industrial Control Panels
- Meter Socket Enclosures
- Motor Control Centers
Also, arc flash labels must now contain Nominal System Voltage and Arc Flash Boundary.
Finally, labels must also contain at least one of the following:
- Available Incident Energy and the Corresponding Working Distance
- Minimum Arc Rating of Clothing
- Required Level of PPE
- Highest Hazard Risk Category for the Equipment
Here are the components of an arc flash label:
- SAFETY ALERT SYMBOL: The triangle-exclamation point symbol
- THE SIGNAL WORD: The word used at the top of the label such as danger, warning or caution,
- THE SIGNAL WORD PANEL: The panel in which the signal word appears
- THE SAFETY MESSAGE: The text describing the hazard
- THE MESSAGE PANEL: The white panel (beneath the signal word panel) containing analysis information, PPE requirements and safety message
Every arc flash label starts with the word "DANGER" or "WARNING" signifying the level of hazard. Danger labels contain a red and white bar and are reserved for a hazard presenting an eminently hazardous situation which will result in death or serious injury. These are typically posted around higher calorie locations.
It's up to the individual to assess the hazard level of an arc flash location. Everyone should know arc flash hazard levels vary by calorie, voltage and work performed. Some locations may present an eminently hazardous situation which will result in death or serious injury that do not necessarily produce an arc flash of 40-cal or greater. These locations will require a danger sign, too.
Generally, danger signs should be reserved for arc flash locations deemed too dangerous to work on without being de-energized. In this case, the danger label should indicate no PPE exists to safely perform work while energized.
Warning utilizes an orange and black bar, reserved for locations presenting a potentially hazardous situation, which could result in death or serious injury. Apply the correct arc flash label to accurately describe the level of hazard. A life may depend on it.
Caution signs are used to mark arc flash analysis locations. Caution signs indicate a potentially hazardous situation which may result in minor injury. Even though caution signs are not appropriate to use in an actual arc flash location, they do provide workers with appropriate information wherever an analysis has been performed and the hazard is deemed to be non-life-threatening. Plus, caution signs signal a piece of electrical equipment has been analyzed and determined to pose a lower level of hazard.
Electrical Equipment Requiring Labels
Meter socket enclosures are usually one of the first pieces of electrical equipment to require arc flash labeling. These enclosures may serve many purposes. A meter socket is generally described as an enclosure that has matching jaws to accommodate the bayonet type blade terminals of a detachable watthour meter. It has a means of connection for the termination of the circuit conductors. It may be a single position socket for 1 meter or multi-position trough-socket for two or more meters.
The panelboard is often the next enclosure downstream from the meter socket. It is used in many other locations. Large facilities may have hundreds of these. NFPA describes a panelboard as a single panel or group of panel units designed for assembly in the form of a single panel including busses and automatic overcurrent devices and equipped with or without switches for the control of light, heat or power circuits - designed to be placed in a cabinet or cutout-box placed against a wall, partition or other support and accessible only from the front.
Switchboards are generally the point at which an incoming power supply divides into separate circuits - each of which is controlled and protected by the fuses or switchgear of the switchboard. In many cases, a switchboard will be the next piece of equipment downstream. The NFPA describes a switchboard as a large single-panel frame or assembly of panels on which are mounted, on the face back or both, switches overcurrent, and other protective devices, busses and usually instruments. Switchboards are accessible from the rear as well as from the front and are not intended to be installed in cabinets. These are your electrical cabinets that have exposed switches, breakers and metering devices on the face.
The NFPA describes a motor control center as an assembly of one or more enclosed sections having a common power bus and containing motor control units.
Industrial control panels are described by Underwriters Laboratories as an assembly incorporating two or more pieces of industrial control equipment or related control circuit devices and provided with interconnecting wiring and terminals for connections in the field. Industrial control panels span various U-L categories.
All the new, required information can be clearly printed onto a single label. The goal is to make labels as legible as possible and display everything a worker needs to work safely.