Thursday, June 25, 2009

Safe Shelters and Indoor Safety from Lightning

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE HUNTSVILLE AL
800 AM CDT THU JUN 25 2009

...LIGHTNING SAFETY AWARENESS WEEK CONTINUES...
...SAFE SHELTERS AND INDOOR SAFETY...

A HOUSE OR OTHER SUBSTANTIAL BUILDING OFFERS THE BEST PROTECTION
FROM LIGHTNING. IN ASSESSING THE SAFETY PROVIDED BY A PARTICULAR
STRUCTURE...IT IS MORE IMPORTANT TO CONSIDER WHAT HAPPENS IF THE
STRUCTURE GETS STRUCK BY LIGHTNING...RATHER THAN WHETHER THE
STRUCTURE WILL BE HIT BY LIGHTNING. FOR A SHELTER TO PROVIDE
PROTECTION FROM LIGHTNING...IT MUST CONTAIN A MECHANISM FOR
CONDUCTING THE ELECTRICAL CURRENT FROM THE POINT OF CONTACT TO THE
GROUND. THESE MECHANISMS MAY BE ON THE OUTSIDE OF THE
STRUCTURE...MAY BE CONTAINED WITHIN THE WALLS OF THE STRUCTURE...OR
MAY BE A COMBINATION OF THE TWO. ON THE OUTSIDE...LIGHTNING CAN
TRAVEL ALONG THE OUTER SHELL OF THE BUILDING OR MAY FOLLOW METAL
GUTTERS AND DOWN SPOUTS TO THE GROUND. INSIDE A
STRUCTURE...LIGHTNING CAN FOLLOW CONDUCTORS SUCH AS THE ELECTRICAL
WIRING...PLUMBING...AND TELEPHONE LINES TO THE GROUND.

UNLESS SPECIFICALLY DESIGNED TO BE LIGHTNING SAFE...SMALL STRUCTURES
DO NOT PROTECT OCCUPANTS FROM LIGHTNING. MANY SMALL OPEN SHELTERS ON
ATHLETIC FIELDS...GOLF COURSES...PARKS...ROADSIDE PICNIC AREAS...
SCHOOL YARDS...AND ELSEWHERE ARE DESIGNED TO PROTECT PEOPLE FROM
RAIN AND SUN...BUT NOT LIGHTNING. A SHELTER THAT DOES NOT CONTAIN
PLUMBING OR WIRING THROUGHOUT...OR SOME OTHER MECHANISM FOR
GROUNDING FROM THE ROOF TO GROUND...IS NOT SAFE. SMALL WOOD...
VINYL...OR METAL SHEDS OFFER NO PROTECTION FROM LIGHTNING AND SHOULD
BE AVOIDED DURING THUNDERSTORMS.

THERE ARE THREE MAIN WAYS LIGHTNING ENTERS HOMES AND BUILDINGS: A
DIRECT STRIKE...THROUGH WIRES OR PIPES THAT EXTEND OUTSIDE THE
STRUCTURE...AND THROUGH THE GROUND. REGARDLESS OF THE METHOD OF
ENTRANCE...ONCE IN A STRUCTURE...THE LIGHTNING CAN TRAVEL THROUGH
THE ELECTRICAL...PHONE...PLUMBING...AND RADIO OR TELEVISION
RECEPTION SYSTEMS. LIGHTNING CAN ALSO TRAVEL THROUGH ANY METAL WIRES
OR BARS IN CONCRETE WALLS OR FLOORING.

IN THE PAST...THE USE OF CORDED PHONES WAS THE LEADING CAUSE OF
INDOOR LIGHTNING INJURIES IN THE UNITED STATES. HOWEVER...WITH MORE
AND MORE CORDLESS AND CELL PHONES IN USE...THE NUMBER OF PHONE
INJURIES HAS BEEN DIMINISHING. AT THE SAME TIME...THE NUMBER OF
CHILDREN INJURED WHILE PLAYING VIDEO GAMES THAT ARE PLUGGED INTO A
WALL OR TELEVISION HAS BEEN INCREASING. LIGHTNING CAN TRAVEL LONG
DISTANCES IN BOTH PHONE AND ELECTRICAL WIRES...PARTICULARLY IN RURAL
AREAS. STAY AWAY FROM WINDOWS AND DOORS AS THESE CAN PROVIDE THE
PATH FOR A DIRECT STRIKE TO ENTER A HOME. DO NOT LIE ON THE CONCRETE
FLOOR OF A GARAGE AS IT LIKELY CONTAINS A WIRE MESH. IN GENERAL
BASEMENTS ARE A SAFE PLACE TO GO DURING THUNDERSTORMS.
HOWEVER...THERE ARE SOME THINGS TO KEEP IN MIND. AVOID CONTACT WITH
CONCRETE WALLS WHICH MAY CONTAIN METAL REINFORCING BARS. AVOID
WASHERS AND DRYERS WINCE THEY NOT ONLY HAVE CONTACTS WITH THE
PLUMBING AND ELECTRICAL SYSTEMS...BUT ALSO CONTAIN AN ELECTRICAL
PATH TO THE OUTSIDE THROUGH THE DRYER VENT.

LIGHTNING ALSO CAUSES SIGNIFICANT DAMAGE TO PERSONAL PROPERTY EACH
YEAR. IN ADDITION TO DIRECT STRIKES...LIGHTNING GENERATES ELECTRICAL
SURGES THAT CAN DAMAGE ELECTRONIC EQUIPMENT SOME DISTANCE FROM THE
ACTUAL STRIKE. TO THE EXTENT POSSIBLE...UNPLUG SENSITIVE ELECTRONIC
EQUIPMENT FROM ALL CONDUCTORS WELL BEFORE A THUNDERSTORM THREATENS.
FOR YOUR SAFETY...DO NOT UNPLUG EQUIPMENT FROM THE WALL WHEN A
THUNDERSTORM IS NEARBY. DONT FORGET TO DISCONNECT TELEVISIONS OR
RADIOS FROM OUTDOOR ANTENNAS! IF YOU PLAN TO BE AWAY FROM YOUR HOME
WHEN THUNDERSTORMS ARE POSSIBLE...BE SURE TO UNPLUG UNNEEDED
EQUIPMENT BEFORE YOU LEAVE.

SUMMARY OF LIGHTNING SAFETY TIPS FOR INSIDE THE HOME

1. AVOID CONTACT WITH CORDED PHONES.
2. AVOID AVOID CONTACT WITH ELECTRICAL EQUIPMENT OR CORDS. IF YOU
PLAN TO UNPLUG ANY ELECTRONIC EQUIPMENT...DO SO WELL BEFORE THE
STORM ARRIVES.
3. AVOID CONTACT WITH PLUMBING. DO NOT WASH YOUR HANDS...DO NOT TAKE
A SHOWER...DO NOT WASH DISHES...AND DO NOT DO LAUNDRY.
4. STAY AWAY FROM WINDOWS AND DOORS...AND STAY OFF PORCHES.
5. DO NOT LIE ON CONCRETE FLOORS AND DO NOT LEAN AGAINST CONCRETE
WALLS.

FOR ADDITIONAL INFORMATION ABOUT LIGHTNING AND LIGHTNING
SAFETY...VISIT THE LIGHTNING SAFETY AWARENESS WEB SITE AT:

HTTP://WWW.LIGHTNINGSAFETY.NOAA.GOV/ (ALL LOWER CASE)

$$

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