NFPA 70E states that the goal of an arc flash risk assessment is a three-step process: Identify a Hazard . Estimate the Likelihood of Occurrence and the Potential Severity of Injury . Determine If Additional Protective Measures are Needed .
What two factors determine arc flash incident energy?
- Distance from the Arc. ...
- Absorption Coefficient of Clothing Worn. ...
- Arc Temperature. ...
- Arc Duration. ...
- Arc Length.
What two factors do arc flash risk assessments determine?
Three factors determine the severity of an arc flash injury: Proximity of the worker to the hazard , Temperature and Time for the circuit to break . Because of the violent nature of an arc flash exposure, when an employee is injured, the injury can be very serious and can even result in death.
What determines arc flash rating?
Incident energy determines the severity of an arc flash. The higher the incident energy, the more severe the event. ... The relationship between distance and incident energy is an inverse squared relationship. In other words, if the working distance is doubled, the incident energy at that distance reduces by a factor of 4.
What is an arc flash risk assessment?
An Arc Flash Risk Assessment or Arc Flash Hazard Study / Analysis is a calculation performed by Professional Engineer to determine the thermal incident energy found at each location which determines the various arc flash boundaries and what personal protective equipment (PPE) must be used in approaching each boundary .
What is needed for an arc flash study?
The nominal voltage and arc flash boundary are required on all labels and at least one of the following: available incident energy with the corresponding working distance, minimum arc rating of clothing or specific level of PPE .
What can cause an arc flash?
It can result from accidental contact with the electrical systems , the buildup of conductive dusts, corrosion, dropped tools, or improper work procedures. The plasma arc has a virtually unlimited current carrying capacity once it’s established. The energy of an arc flash converts primarily to heat and light.
What are the arc flash boundaries?
Simply put, the arc flash boundary is the distance at which an electrical arc can flash/expand outward , which may endanger employees working on electrical equipment. People that are not adequately protected must stay away from a potential arc flash source by this calculated minimum distance at all times.
Who requires an arc flash study?
Since the 2002 edition of the National Electrical Code (NEC) there has been the requirement, in Section 110.16 Arc-Flash Hazard Warning (see Figure 1) to install arc flash warning labels on industrial control panels, motor control centers, panelboards, and switchboards that are likely to require examination, adjustment ...
At what voltage can arc flash occur?
Most 400 V and above electrical services have sufficient capacity to cause an arc flash hazard. Medium-voltage equipment (above 600 V) is higher potential and therefore a higher risk for an arc flash hazard.
What does an arc flash study tell you?
An arc flash study is the evaluation of a workplace facility by an electrical safety expert to determine hazards and risks in relation to electrical systems . ... A review and analysis of the facilities written electrical safety program can also be included.
What are the dangers of arc flash?
Dangers of arc flashes
An arc flash can cause minor injuries, third degree burns and potential death as well as other injuries including blindness, hearing loss, nerve damage and cardiac arrest. Fatal burns can occur when the victim is several feet from the arc.
How often does an arc flash study need to be done?
the NFPA-70E still recommends that arc flash studies be updated when a major modification or renovation takes place and at intervals not to exceed 5 years .
Is arc flash required by OSHA?
The § 1910.335 (a)(2)(ii) safeguard selected — shield, barrier, or insulating material — must fully protect employees from electric shock, the blast, and arc-flash burn hazards associated with the incident energy exposure for the specific task to be performed.
How do you choose arc flash PPE?
- Carry out a Risk Assessment. This will involve an Arc Flash hazard analysis to determine the potential incident. ...
- Determine the Arc Rating. This calculates the Arc Thermal Performance Value (ATPV) in cal/cm2 and. ...
- Select the PC & PPE.
