Tuesday, August 12, 2008
System maintenance a key part of arc flash safety
An article in IMPO Magazine, written by Joseph Weigel of Square D Services, Schneider Electric, discusses the important role that electrical system maintenance plays in protecting against arc flash.Fault clearing time is central to mitigating the danger posed by an arc flash. However, without proper maintenance, upstream overcurrent protective devices may not be able to respond adequately in the event of an arc fault. Weigel writes,
When these devices are not maintained on a regular basis, their clearing time may increase, allowing more energy to be released in an event. If maintenance is deferred long enough, it may result in a worst-case condition that may render the device completely inoperable, meaning it will not open to clear a fault of any magnitude.
An improperly maintained electrical system may look safe on paper, but pose significant dangers in reality. Malfunctioning protective devices can greatly increase the incident energy released by an arc flash; devices which don't function at all may as well not exist.
NFPA 70B, "Recommended Practice for Electrical System Maintenance," provides a useful guide to ensuring that protective devices maintain full functionality. Unfortunately, NFPA 70B compliance is far from universal, as it is a voluntary standard not required by OSHA.
Labels: Arc Flash, Electrical Hazards
posted by Daniel Nighting
| This Arc Flash Post and 4 Comments
| 
NFPA 70E Blog | Arc Flash Labels | Arc Flash Label Printers | DuraLabel Supplies | Free Trials
4 Comments:
Would an arc flash necessarily shock a person who was hit by it or could he or she just be burned?
Arc flash and electrical shock are two separate hazards. It is possible that they can be combined--if fault current arcs between equipment and a worker's body, for instance.
Workers up to 10' from an arc fault can be burned, blinded, knocked down, or otherwise injured by the blast; anyone in the vicinity runs a risk of injury. By contrast, electrical shock is usually a hazard only for the worker closest to live equipment.
what changestakes place in human body when itgot electric shock and when it got arc flash
Introductory information about the effects of electrical shock is available online at: http://www.allaboutcircuits.com/vol_1/chpt_3/2.html
An arc flash is very different. At it's worst it is a violent explosion that includes extremely high temperatures, a strong shock wave, vaporized metal, other dangerous gases, shrapnel (pieces of metal and other materials), and loud noise. The effects vary depending on the severity of the arc flash blast, protective measures taken, the equipment arrangement, and closeness to the source of the blast.
Post a Comment
Links to this post:
Create a Link
<< Home