In the duration and aftermath of flooding, you may be faced with a situation where your house or surrounding area is flooded, and electrical points submerged. If you must wade into potentially electrified waters with no tools to test for electricity, there is a technique of last resort you can use. We also cover how to prepare for flooding and what to do if someone falls into electrified water.
Warning: live electricity, including when flowing in water is dangerous and can kill you, and you should avoid it where possible. This information is provided as-is based on a good-will basis based on an article first published for the 2011 Bangkok Floods, and may not be appropriate for your situation. We accept no liability for any damages as a result of use of this information. You should take appropriate precautions by evacuating before you are put into a position where you must use this information.
If your house in danger of flooding or is in the process of being flooded, and you have not evacuated before then, you should make all efforts to turn off the main switch in the switch box. When doing so, make sure you are standing on dry land and NOT submerged in water. Use clothes to cover your hands when switching off for additional safety.
Testing if there is electricity flowing through the water
If your house is flooded and you have not have had the chance to turn off the main switch, or have reached a flooded area, there is a possibility that electricity may be leaking from power points or submerged power lines from your own house or from others. If you don't have equipment to test for electrified water, and you need to enter the waters, you can use the following technique you can lightly touch the water using the back of your hand. Do NOT use the front, as that will electrocute you. Also, do NOT submerge your hand into the water as it may kill you.
In the event you feel a tingly sensation, it means there is a current still flowing. Identify the source of the current and turn it off before retesting and entering the water, or wait for rescue.
Why we should use the back of the hand only:
If you use the back of the hand, the electric shock will cause your muscles to cramp, automatically pulling your hand out of the water. If you use the front of the hand the electricity will make your muscles close & your hand will submerge into the water.Why having a Ground Fault Interrupter might be a good idea:
If you live in a flood area, it may be safer for your main circuit breaker to have a Ground Fault Interrupter (GFI), also known as an Earth Fault Breaker. This is a circuit which detects leaking current from the dangerous side of the circuit, and if the current does not return on its normal path. Not only will this automatically turn off your electricity during a flood but will protect your whole house all the time from possible electrocution and from some possible (but not all) electrical fires.Why electrified water will kill you:
Flood water has the same voltage as earth, which is 0 Volt. It is the best electrical earth that can be found, with virtually no resistance.
The danger comes from a person standing with feet in the water, so he is perfectly grounded to 0 Volt. Touching an electrical device that has voltage on the enclosure will lead to a current through body to earth. The lower the resistance, the higher the current.
A human can only hold 30mA, which is a very low current. Short circuits, wrong connections, ungrounded neutral are all causes that can lead to voltage on enclosure or other parts. If you are standing in water, do not touch any device that has an electrical connection (microwave, fridge, cooking stove, but also street lamps made from metal).
If someone has fallen into water with electricity still flowing, and is being electrocuted
Do NOT follow that person into the water, as you too will be electrocuted. Instead, use a rope, dry towel or anything to get the person to dry land. Do NOT touch the water.
Being electrocuted for more than 0.04 seconds will likely result in the victim’s heart stopping, so you must take their pulse and immediately perform CPR.