Fighting electric fires

[john signorelli]

Is their inforation available on "approach distances" for fighting energized (eg.- exposed conductors, high voltage (13 kV)) electric fires with water stream (jet) or spray ??

[eyecue]

Yes there is! Its in a book called the FIRE CHIEFS handbook and may also be in Mordern Suburban Firefighting. It lists stream size and distance from source of electric current and how much conduction the nozzleman will take with the application of water.

[eyecue]

I wouldnt like to have been in this study!
Voltage nozzle 1 1/8" nozzle 1 1/2"
1,100..............6'......... ...... 9'
2,200.............11'......... ......16'
3,300.............15'......... ......22'
5,500.............18'......... ......27'
6,600.............19 ...............29'
11,000............20 ...............30
22,000............25 ...............33
33,000............30 ...............40

Those are distances that you can be from a live source and apply water safely. A fog stream doesnt conduct water as well as a solid stream. The following chart takes into account how much current flows back through the nozzleman. The resistance rating of t he fireman is USUALLY about 3000 ohms

Voltage 500ohm 1000 ohm 2000ohm 3000ohm 4000
440......11.......7.....4.5... ......3......3
1,100....30.......18....12.... .....8.5....6.5
2,200....*........30....20.... .....15.....12
4,400....*........35....28.... .....23.....19
6,600....*........*.....33.... .....30.....26
13,200...*........*......*.... .....33.....31
22,000...*........*......*.... ......*......*

The nozzle is 1.25" The nozzle pressure is 50 psi. This chart takes into account that 30 milliamps is all that you can take.

[This message has been edited by eyecue (edited 06-10-2001).]

[john signorelli]

Your last sentence states 30 milliamps. Should this have been 3.0 milliamps ?

Besides the references cited, do you know of any National Standards that include these or similar facts of information? (NEC, OSHA, IEEE, NFPA, etc.) I have only been able to find approach distances that apply to AIR as the medium between conducting points.

[eyecue]

3 is the threshold of sensation. 30 is considered painful and may result in injury
loss of consciousness. But it is still not fatal in most cases. I am not sure what you mean about air as the medium to approach in. What other types of medium do you approach in?