Definitions :
- current—the movement of electrical charge
- voltage—a measure of electrical force
- circuit—a complete path for the flow of current -
- You will receive a shock if you touch two wires at different voltages at the same time.
- ground—a physical electrical connection to the earth
- energized (live, “hot”)—similar terms meaning that a voltage is present that can cause a current, so there is a possibility of getting shocked.
- conductor—material in which an electrical current moves easily.
- neutral—at ground potential (0 volts) because of a connection to ground.
NOTE : You will receive a shock if you touch a live wire and are grounded at the same time.
NOTE : When a circuit, electrical component, or equipment is energized, a potential shock hazard is present.
An electrical shock is received when electrical current passes through the body. Current will pass through the body in a variety of situations. Whenever two wires are at different voltages, current will pass between them if they are connected. Your body can connect the wires if you touch both of them at the same time. Current will pass through your body.
In most household wiring, the black wires and the red wires are at 120 volts. The white wires are at 0 volts because they are connected to ground. The connection to ground is often through a conducting ground rod driven into the earth. The connection can also be made through a buried metal water pipe. If you come in contact with an energized black wire—and you are also in contact with the neutral white wire—current will pass through your body. You will receive an electrical shock.
If you are in contact with a live wire or any live component of an energized electrical device—and also in contact with any grounded object—you will receive a shock. Plumbing is often grounded. Metal electrical boxes and conduit are grounded.
Your risk of receiving a shock is greater if you stand in a puddle of water. But you don’t even have to be standing in water to be at risk. Wet clothing, high humidity, and perspiration also increase your chances of being electrocuted. Of course, there is always a chance of electrocution, even in dry conditions.
You can even receive a shock when you are not in contact with an electrical ground. Contact with both live wires of a 240-volt cable will deliver a shock. (This type of shock can occur because one live wire may be at +120 volts while the other is at -120 volts during an alternating current cycle—a difference of 240 volts.). You can also receive a shock from electrical components that are not grounded properly. Even contact with another person who is receiving an electrical shock may cause you to be shocked.
To prevent an incident like this, employers should take the following steps:
• Establish proper rules and procedures on how to access electrical control cabinets without getting hurt.
• Make sure all employees know the importance of de-energizing (shutting off) electrical systems before performing repairs. • Equip voltage-regulating equipment with color-coded wiring.
• Train workers in CPR.
You can prevent injuries and deaths by remembering the following points:
• If you work on an electrical circuit, test to make sure that the circuit is de-energized (shut off)!
• Never attempt to handle any wires or conductors until you are absolutely positive that their electrical supply has been shut off.
• Be sure to lock out and tag out circuits so they cannot be re-energized.
• Always assume a conductor is dangerous