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November 23, 2016 Previous day Next day

When many of us think of fire in high-rise buildings, our minds go first to the terrorist attacks on the World Trade Center in New York City on September 11, 2001. That means that we remember the deadliest high-rise fire in world history.  In reality, fires in high-rise buildings are usually smaller than fires in other buildings.

In high-rise buildings, fire spread beyond the room of origin in 1% of the dormitory fires; in 4% of the fires in apartments or multi-family housing, hotels, and properties that care for the sick; and in 10% of the office buildings.  In buildings that were not high-rise, fire spread beyond the room of origin in 2% of the dormitory fires, 9% of the fires in properties that care for the sick, 10% of the apartment or multi-family housing fires, 11% of the hotel or motel fires, and 21% of the office building fires.

According to NFPA’s new report on High-Rise Building Fires, U.S fire departments responded to an estimated average of 14,500 structure fires in these properties per year in 2009-2013.  These fires caused an average of 40 civilian deaths, 520 civilian injuries, and $154 million in direct property damage annually.  For this analysis, a high-rise building is a building that has at least seven stories above grade.  

Just five occupancy groups accounted for almost three-quarters (73%) of all high-rise building fires:

  • Apartments or other multi-family housing (62%);
  • Hotels (4%)
  • Dormitories (4%)
  • Office buildings (2%)
  • Facilities that care for the sick (2%)

The report provides more details about high-rise fires and fires in shorter buildings in these five occupancy groups.

Compared to fires in buildings that were not high-rise, fires in high-rise buildings were much less likely to spread beyond the room or floor of origin. High-rise buildings were more likely to have fire detection and much more likely to have wet pipe sprinklers than shorter buildings.  While construction type was dropped from the current version of the National Fire Incident Reporting System, data from 1980 to 1998 showed that high-rise buildings were much more likely to have fire-resistant construction.

Most high-rise building fires start below the seventh floor. The kitchen or cooking area was the leading area of origin in all five occupancies, regardless of height. 

And for those of you interested in the really big high-rise fires, Appendix A of NFPA’s High-Rise Building Fires report has a list of the ten deadliest high-rise building fires in the world.  Most in the list link to previously published NFPA material about these blazes. 

The causes of high-rise building fires have a lot in common with fires in other properties. We know that smoke detection, fire sprinklers, and compartmentation are vital to fire safety.  Today’s high-rise buildings are more likely to have this protection than are other properties.  The statistics remind us how important this protection is.

NFPA joins CPSC to demonstrate the fire dangers of turkey fryers in this live burn. NFPA strongly discourages the use of turkey fryers and continues to believe that turkey fryers that use cooking oil, as currently designed, are not suitable for safe use by even a well-informed and careful consumer. These turkey fryers use a substantial quantity of cooking oil at high temperatures and units currently available for home use pose a significant danger that hot oil will be released at some point during the cooking process. In addition, the burners that heat the oil can ignite spilled oil. The use of turkey fryers by consumers can lead to devastating burns, other injuries, and the destruction of property. NFPA urges those who prefer fried turkey to seek out professional establishments, such as grocery stores, specialty food retailers, and restaurants, for the preparation of the dish, or consider a new type of "oil-less" turkey fryer."

 

For more safety tips and information on safe cooking visit www.nfpa.org/thanksgiving

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There are many statements being made in the field that NFPA 70E® has a preference to use the incident energy analysis method over the PPE category method. One of the stated reasons for this has been that it is first in the standard and the first requirement is always the preferred method.  None of this is true.  Either method can be used if applicable. Something is only a hierarchy if the standard states the list is in a discrete order (think hierarchy of risk controls which are in a specific descending order of effectiveness or that the explicit primary requirement is that an electrically safe work condition be established.)

NFPA 70E permits the use of either the PPE category method or the incident energy analysis method. The standard does not have a preference since each method has its merits and its limitations. Both achieve a level safety for the worker when energized work is justified. Why use one method over the other? Let’s look at some reasons for each. First, both require that the hierarchy of risk controls be used.  Both require that you know the available short-circuit current and fault-clearing time. From there the methods diverge.

To use the PPE category method the equipment must be listed on the table. The specific parameters for that piece of equipment cannot be exceeded. The PPE category and the arc-flash boundary are given. A benefit of the table method is that it does not require that an extensive incident energy evaluation be conducted. It is potentially a quick and effective way to properly label equipment. It provides a simple four level system for required PPE within the facility.

There are limitations in the use of the table method. If the equipment is not on the table or if even one parameter is exceeded the method cannot be used. If the working distance will be closer than specified the method cannot be used.  A detriment is that if the actual circuit parameters are well below those specified the PPE category remains the same. Although the hierarchy of risk controls may lower the risk to the worker the PPE category remains the same. The table is either GO or NO GO. There is no interpolation.

A benefit of using the incident energy analysis method is that it can be used on any piece of electrical equipment. It allows a finer pinpoint on the incident energy rather than the broad range of the category method. It can be adjusted for a change in current, clearing time or working distance.  One detriment is that it is a very detailed process typically requiring the assistance of an outside consultant or the use of a computer program to perform the calculation. Although no specific method of calculation is required by NFPA 70E, the incident energy analysis method requires that you select the most appropriate calculation method for the type of circuit. This method is often a longer process than the table method. Depending on your viewpoint, having the ability to specify individual PPE for each piece of equipment may be a benefit or detriment.

There are other benefits, detriments and shortcomings of both methods. Regardless of the method selected, of the reason for selecting one method over the other, or other issues associated with a particular method, the main concern is protecting the worker. NFPA 70E allows both methods to used equally. Both may be used in the same facility but must not be used on the same piece of equipment.  You must decide which one is applicable for your equipment.

Next time: A misuse of the PPE category tables.

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