There was a topic which came up at our last night at our dept. meeting about what should be done at an electrical fire. The question I need an answer to is... Taking into account length and diameter of hose(creating friction loss) which nozzle, hose stream and distance away would not allow the electricity to jump through the water droplets back to the nozzle. We use f-500 at 3% on some fires and our pump runs at 125psi with a preconnect 200 feet of 1and 3/4 inch hose with a 1 and 1/2 fog nozzle that maxes out at 100psi.
I agree that the power should be shut off first thats only common sense, but, the area we are in is a small cottage and resort community and there are alot of "bandaids " used to fix homes here and shutting down the main breaker does not always shut the power down completely ie. sub panels and owners who dont know or dont care about how the past owners "fixed" the house in order to sell. We had an incident where the power was shut off to a burning breaker panel near some boat docks and after the fire was out there was still electricity to that area. Owner had no idea how to shut it down and wasting time trying to find out could have meant several boats and docks would have been damaged.
The IFSTA manual says use fog patterns with at least 100 psi nozzle pressure but that sounds low to me im thinking 150psi to be safe and what angle of fog pattern is to tight to allow electricity to jump, it does not say. And will f-500 help or hinder this attack on the fire.
You do not use water on a live electrical fire! The power should always be turned off first. Even if water was used and you are still alive. The fire will still come back without disconnecting.
First off as stated many times already her POWER OFF! The fog pattern and stream droplet is a false sense of security. For 120volts you may get away with it, however as the voltage rises so does the potential for the electrons to arc across the gap. just go to youtube and type in electric arc and a bunch of good illustrations will come up showing high voltage arcing across big gaps. i work for an electric utility and we have minimum safe distances for different voltages because of the potential. Electricity is invisible, odorless, silent, and deadly. An energized conductor can lay quietly on the ground until something or someone gives it a path to earth. If you are the unlucky conductor death is the likely result. Our philosophy is a wire, ANY wire is considered energized until tested, grounded and tagged as de-energized. Utilities spend big bucks training their workers in how to safely deal with energized lines of ANY voltage and we in the fire service are for the most part lacking in this area.
In 12 years i have never had a problem ir ever heard of a problem with house hold current coming back thru a hose line. from the meter thru the house that does not concern me. but from the meter to the pole wouldnt try it ever. Not sure what voltages your talking about on boat docks but as long as its not over house hold current i wouldnt worry about it. I KNOW THIS IS WHAT EVERYONE SAYS LIKE A BROKEN RECORD BUT I WOULD LIKE TO HAVE IT CUT OFF FIRST JUST FOR PEACE OF MIND. When we pull meters at houses im not concerned as much with house hold current from the meter into the house as i am with a fireman accidentally getting tangled or touching a live interior line.
1) if you don't de-energize the power, it's likely to re-ignite. Don't dick around fighting it, protect your exposures and figure out how to shut her down
2) You talk about foam - BAD IDEA! The foam layer is quite conductive.
3) If you can't shut it down, back off, protect your exposures, and thank the gods that most western countries have building codes that prohibit that sort of construction.