UNDERSTANDING ELECTRICAL HAZARDS
SOMETIMES lovers say to each other that “love flowed in my body like electricity the first day I saw you.” Such imaginary electricity is totally harmless and it only occurs in the love world. But when the real electricity found in the real world flows in you, you will never wish for it to flow in you again – that is if you survive. Electricity is dangerous. Electricity is a human need. Yes electricity may not be a basic human need but it is definitely an essential need to everyone. Life without electricity would make human survival unbearable, if not impossible. Electricity has become an integral part of our lives. Without electricity, homes would be in dark at night, factories world shut down and mortuaries locked. All electrical appliances would become useless and technology impractical. Electricity is widely used in our homes, offices, factories, mines, farms and hospitals just to mention a few. Among other uses, electricity is used in operating machines, heating, cooling, lighting, cutting and welding. Electricity has made our lives more pleasant and convenient. But this commodity that has simplified our lives has serious hazards and risks. We need to understand these hazards and know how to control them.
Every time you are using electricity, you should bear in mind that electricity is dangerous. Every electrical equipment must be selected, installed, used and maintained properly and safely. All electrical works such as installation, maintenance and repair must be carried out by a competent person. Awareness of electrical hazards is necessary to avoid accidents. The major hazards and risks of electricity include electric shock, electric burns, damage to equipment and electrical fires. Let’s start by discussing what electricity is and how it behaves. Electricity is the flow of electrons in a conductor. An electron is an electrical charge. When this electrical charge is flowing, it results in electricity. But if this electrical charge is stationary, it results in static electricity. Both electricity (flow of electrical charge) and static electricity (static electrical charge) are dangerous. In this article, we are looking at electricity, not static electricity. The flow of electrons is referred to as current. Technically speaking, electricity doesn’t flow. What flows is current. But in everyday life, we often use the phrase ‘electricity is flowing.’ Since we are not training electrical engineers, we will maintain the everyday language common to everyone. I am using current and electricity interchangeably. If I use ‘electricity flowing,’ bear in mind that I refer to the flow of current – electrons or electrical charge.
The electrons require energy to move or flow in a conductor. This energy is provided by potential difference or voltage. The conductor provides the path which electricity follows. So any material that allows electricity to flow in it is called good conductor.
On the other hand, any material that does not allow electricity to flow in it is a bad conductor. Bad conductors are used as insulators. Electrons experience some opposition or resistance as they flow in the conductor.
This resistance is known as electrical resistance. The path followed by electricity is called electric circuit.
A complete electric circuit starts and ends with the power supply. The power supply is connected by a conductor to an electric equipment and another conductor from the equipment connects the equipment to the power supply. The electron moves from the power supply to the equipment and back to the power supply to start the cycle again. For the electrons to continue making this motion continuously, continuous supply of energy is required.
The journey of electrons start at the power supply. The electrons gain energy from the power source and flow to the equipment through the conductor. This conduct which connects the power source to the equipment is called live conductor or live wire. Once the electrons reach the equipment, the energy they acquired from the power source will be lost to the equipment which will convert it into another form of energy depending on its function.
As you might recall from your physics, energy cannot be created or destroyed but it can be changed from to another. For instance, an electric motor will convert electrical energy into motion which is kinetic energy, an electric heater from electrical energy to heat energy and an electric bulb from electrical energy to light energy. From the equipment, electrons will start the journey back to the power source through a conductor to get some more energy and repeat the process. This conductor which links the equipment to the power source is called neutral conductor or neutral wire.
As you can see, the complete circuit is made up of two wires – a live wire and a neutral wire. However there is an extra conductor to every circuit for safety. This third conductor is called earth conductor or earth wire.
The earth wire connects the circuit to the earth or ground. This connection is called earthing or grounding. Earthing is very important because, whenever there is unintended interruption to the circuit, the earth wire will provide an alternative path to the ground and discharge the harmful energy to the earth.
In simple terms, the earth wire provides an ‘emergency exit’ for electricity to safely flow to the earth and discharge the electrical energy.
Assuming that unintended interruption occurs to the circuit and earthing is not provided, the electrical energy which should have been discharged safely via earthing may cause harm. Let’s recap on what we have discussed so far. Current is the flow of electrons or charge which is basically electricity. Voltage provides energy electrons require to flow. Resistance is the opposition to the flow of electrons. A circuit, which is a path electrons follow, is made up of a power source and an equipment connected to each other by conductors. Conductors are usually wires. A circuit has three wires – a live, neutral and earth wires. Earth wire is included for safety reasons.
This sounds pretty simple. So where is the danger of electricity? Well, electrical danger can arise from anywhere
Electricity is widely used in our homes, offices, factories, mines, farms and hospitals just to mention a few. Among other uses, electricity is used in operating machines, heating, cooling, lighting, cutting and welding. Electricity has made our lives more pleasant and convenient.
in this seemingly simple process. Electrical danger arises when the two conductors meet together, when the conductors are forced to carry more electricity than they can handle, when equipment is forced to handle more electricity than its design capacity or when electricity flows in a human body. The key to electrical safety is to ensure that none of the above occurs. Let’s now look at the electrical hazards in more detail. The first electrical hazard is the effects electricity has when it flows in a human body. When it flows in your body, electricity can cause electric shock or electrical burns or both. Most people know that electricity kills. But what they don’t know is how it kills. For most people when they think of good conductors, they only think of wires.
Very few people realize that even the human body is a good conductor. You must always remember that electricity is designed to flow in wires, not in you. When electricity flows in you, it can cause serious injuries which, in certain cases, may be fatal.
The effects of electricity flowing in your body depends on the pathway taken, frequency of current, duration of flow and amount of current.
The effects become more severe if the pathway includes vital body organs like the heart. For instance electricity following through hand-tohand path across the chest is more dangerous than electricity following through the hand-to-foot path.
As for the other factors, the higher the frequency, the more the severity; the longer the duration of flow, the more the severity and the more the amount of current, the more the severity.
Electric shock is the abrupt reaction of the human body to the flow of electricity. This is accompanied by pain and, in severe cases, electrical burns. The flow of electricity in your body will cause the vibration of the muscle which makes it difficult for you to release the conductor. If the chest is in the path of electricity, electricity will disrupt the respiratory movement causing asphyxia- deprivation of oxygen.
Furthermore, electricity passing through the chest may also cause fibrillation of the heart which is the vibration of the heart muscle disrupting the normal rhythm of the heart. In certain cases, electricity flowing in your body can also cause the heart to completely stop functioning causing cardiac arrest. Electric shock usually occurs when you become the route of electricity to the earth for a live conductor.
Electrical burns are burns caused by electricity. When electricity experiences high electrical resistance of your body usually on the skin, the result is an electrical burn. Electrical burns are more severe than burns from heat or fire as they are usually deep and slow to heal. Heat or fire burns the body surface which is the skin but electricity can penetrate and burn tissues deep inside the body causing damage to the muscles and blood cells. Research shows that the human body has the highest resistance on the skin. The body beneath the skin has very little resistance due to high water content.
The skin which is wounded, bruised or damaged will have low resistance increasing the risk of electric shock. When the skin is dry, electrical resistance can reach approximately 100 000ohms. However when the skin is wet, electrical resistance can reduce to as low as 100ohms.
This means that wet skin allows the flow of electricity better than a dry skin. The implication is that the dry skin can easily result in electrical burns while the wet skin can easily result in electric shock.
The second electrical hazard is the effects electricity has on nonhuman materials.
These materials can be the circuit, equipment and materials around it. It is common knowledge that electricity can cause damage to equipment or electrical fire. I am sure you have heard of fire incidences reported to have been caused by electric fault. Electric fault is caused by different things including short circuit and overheating. Short circuit occurs when the circuit is broken in some way so that current flows directly from live wire to neutral wire or directly to the earth rather than to the equipment.
Overheating is caused by overloading the circuit which is basically allowing more electricity to flow in it beyond its designed capacity. Poor ventilation, loose cables and bunching of cables promote overheating thereby increasing the risk of fires and explosions especially if there are flammable materials nearby.
Electricity is good but dangerous. We need to use it safely. Electricity poses many hazards such as electric shock, burns, fire and damage to the equipment. These risks have other secondary effects. In future we will explore more exciting topics under electrical safety. So keep on reading. You can’t afford to miss. Don’t just use electricity, use it safely. Until next week, stay safe. Zambia needs you.
For your comments, contact the author on cell +260 975 255770 or email: marksucceed@gmail.com Mark Kunda—Safety Consultant