www.firefightingincanada.com

Features Structural Training
Trainer’s Corner: Hydro guide for first responders


March 19, 2008
By Ed Brouwer

Topics

As I was researching this column on electrical safety I came across some exciting news – BC Hydro is in consultation with the B.C. Fire Training Officers Association to develop a train-the-trainers course on electrical hazards for firefighters.

edbrouwerAs I was researching this column on electrical safety I came across some exciting news – BC Hydro is in consultation with the B.C. Fire Training Officers Association to develop a train-the-trainers course on electrical hazards for firefighters.

BC Hydro has given us permission to reproduce a portion of its Electricty Take Care book, a guide to electrical hazards facing firefighters. We hope the information will benefit your department.

According to the BC Hydro publication, about 80 per cent of the human body is water, which is one of the best conductors of electricity. Electricity will go through the body to reach the ground about as easily as it goes through a power line. The body’s tolerance to electric shock depends on the amount of current and how long it lasts.

We have an electrically powered brain, which is so efficient that it operates on currents so tiny that they can barely be detected. Our brains use these tiny signals to operate our heart and other muscles by remote control. Unfortunately, there’s no fuse box.

The closest thing we have to a fuse is the sensation known as pain, which is the body’s way of warning us to stop doing whatever it is that’s causing it. But pain is no defence against a stiff shot of electricity, because even a small amount of electricity can overwhelm the signals the brain puts out.

Since our muscles obey the strongest current, they clench up and twitch in an almost unbelievable case of cramps when they are exposed to an electrical current. Current that’s just strong enough to run a five- or 10-watt lightbulb can kill; current strong enough to run a 100-watt bulb is more than 10 times what it could take to kill a human being.

trainers
BC Hydro’s Electricity Take Care book is a guide to electrical hazards faced by firefighters.

TOUCH POTENTIAL
If an object such as a tree or ladder comes in contact with a high-voltage power line, and then a person touches the object, electricity will flow through the object, then through the person, to the ground. This may easily result in serious injury or worse.

STEP POTENTIAL
Electricity seeks all paths to the ground. When it reaches ground, it spreads out like ripples in a pool of water. At the point where it reaches ground, voltage (pressure) is at full force. That’s a danger. Picture yourself standing next to a downed wire that’s pumping electricity into the ground. With both feet together, you’re fairly safe; there’s no reason for the electricity to flow up one of your legs and down the other because the pressure is the same under both feet.  If you step away from the wire, you can create a difference in pressure and become part of the electrical circuit. If possible, stand still until someone cuts the power. If not, shuffle away without moving your feet more than a couple of inches at a time. Or, if you must, hop, but take very small hops to ensure that you keep your balance.

Emergency personnel should be aware of the potential for electrical shock involving trees and tree limbs on and near power lines. This the single biggest cause of fatalities among rescue workers.

Power lines are programmed to shut down if an object like a tree limb touches them but this doesn’t always happen. During storms, for example, some lines may remain live and power will continue to flow through the object to the ground, making it dangerous to be in the the area around the object. Even if a line does “kick out” or shut down, it can quickly be re-energized by remote equipment. 

Firefighters called to a fire or rescue should first size up the situation and determine if trees, branches or any other objects are contacting the lines or are in danger of contacting them. If this is the case, do not approach until a representative from the local electric utility authority has made the area safe.

DOWNED POWER LINES
Your main role is to stop people from getting hurt. Downed power lines are one of the most common emergency situations firefighters face because lines can be brought down by a storms, ice, trees or vehicles hitting power poles.
Park well away from fallen lines. At night, use a flashlight through the windows and make sure there are no power lines nearby before you step out of the vehicle.

Live wires seldom leap about and give off sparks like they do in the movies. What’s more, a line that’s not energized can come to life at any moment because automatic switching equipment is designed to restore power to subscribers when there’s a fault. Don’t become a victim.

No matter how badly someone is injured, firefighters can’t help if they get electrocuted. So, never touch anything that’s in contact with a downed line – not a car, not a victim, not a puddle of water, not a tree.

Unapproved rubber gloves will not protect rescue personnel nor will a dry stick, rubber hose or piece of rope. Call the local electrical utility authority immediately. Secure the area and keep everyone at least 10 metres back from any hazard.

If a live line falls on a metal object such as a fence, electricity may be conducted to other points. The ground surrounding a downed wire will be energized. A live wire may burn through when in contact with something on the ground. One end may then curl up and roll along the ground, causing injury.

DOWNED LINES ON VEHICLES/VEHICLES ON DOWNED LINES
If the driver is able and if the vehicle is operable, instruct the driver to slowly drive 10 to 15 metres clear of the wires and any pools of water (these could be energized by the wire). Keep onlookers well back as a wire can spring in any direction when it’s released by the vehicle.

If the driver is injured and/or the vehicle cannot move, instruct everyone in the vehicle to stay put until hydro crews arrive.

If the vehicle is on fire, use the following as a last resort if you can’t extinguish the fire: if the occupants are uninjured, instruct them to get out with a standing jump or by taking large steps away from the vehicle but make sure they understand the danger of touching the vehicle and the ground at the same time.

Tell the occupants to keep their feet together as they jump. Then, make them aware that the safest way to move away from the vehicle is to shuffle their feet, if the terrain permits, or keep both feet together and take small hops away from the vehicle. This is necessary to avoid becoming a victim of step potential.

FOG SPRAY
If fire control is necessary at any incident involving the electrical system, apply water with a wide fog spray. The water pressure must be a minimum of 100 psi with a minimum 30-degree fog pattern. The use of a straight stream could result in electricity passing through the stream and back to the nozzle. The fog spray should be applied from a distance of at least 10 metres. Electricity can be conducted through the ground, especially wet ground at a fire scene.
Do not use foam as it is a very good conductor.

The information here represents a small part of BC Hydro’s training manual and associated firefighter training program and was developed to provide guidance to British Columba firefighters. Readers should speak with their local power utility regarding firefighter safety within the context of the electrical system in their area. Thanks to BC Hydro for its contribution to firefighter safety.

Ed Brouwer is the chief instructor for Canwest Fire in Osoyoos, B.C., and the training officer for West Boundary Highway Rescue. The 18-year veteran of the fire service is also a fire warden with the B.C. Ministry of Forests, a first responder, level III, instructor/evaluator and fire-service chaplan. E-mail: ed@thefire.ca


Print this page

Related



Leave a Reply

Your email address will not be published. Required fields are marked *

*