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Understanding Electricity – Simple Answers to Common Questions

Our electrical safety trainers field some pretty tough questions from electricians during NFPA 70E training classes. But they also get simple questions quite often from people not as well versed in electrical safety as the electricians. Here are a few of the most common simple questions posed, along with answers.

What is electricity, and how is it produced for use?

Electricity is the movement of tiny particles called electrons. You’ve probably experienced static electricity—like when you rub your feet on a carpet and then touch a doorknob, feeling a little shock. What’s happening is that you’re building up extra electrons, and when you touch the metal, they quickly jump from your hand, creating a spark.

Now, imagine if we could control that electron movement in a steady, predictable way. That’s what power plants do!

In most U.S. power plants, electricity is made using generators, which work kind of like giant versions of a hand-crank flashlight. Instead of your hand turning the crank, power plants use energy sources like burning coal, natural gas, or even rushing water to spin a turbine (a big fan). The turbine then spins a generator, which moves a magnet inside coils of wire. This motion pushes electrons through the wire, creating electricity.

This electricity travels through power lines to homes, schools, and businesses, where it powers everything from lights to computers!

What is the difference between AC and DC current?

Electricity flows in two main ways: Alternating Current (AC) and Direct Current (DC).

• • AC (Alternating Current) is the type of electricity that comes from power outlets in homes and buildings. The electric charge moves back and forth very fast, changing direction many times per second. This is great for sending electricity over long distances.
  • DC (Direct Current) is electricity that flows in only one direction, like in a battery. Devices like laptops and smartphones use DC power, which is why they need chargers to convert AC from the wall into DC.

What do the terms volts, amps, and watts all mean, and how are they related to each other?

Let’s break down these terms using a 100-watt light bulb installed on a 10-amp, 110-volt circuit:

• • Volts (V) – Think of voltage like water pressure in a hose. It’s the force that pushes electricity through the wires. In the U.S., most homes have 110-120 volts in regular outlets.
  • Amps (A) – This measures how much electricity is flowing, like how much water is coming out of the hose. Your circuit can handle up to 10 amps.
  • Watts (W) – This is the total power being used. It’s like how much total water is spraying from a hose. A 100-watt bulb means it needs 100 watts of power to light up.

The relationship between these is simple: Watts = Volts × Amps
For your light bulb: 100 watts = 110 volts × about 0.9 amps

That means your light bulb uses less than 1 amp of electricity, so your 10-amp circuit can safely handle several of them.

How is it that electricity can shock someone even when they do not actually touch an energized line or part?

Electricity doesn’t always need direct contact to shock you—it can jump through the air if the voltage is high enough. This is called an arc flash or electrical arcing.

Think of lightning—it’s electricity moving through the air from a cloud to the ground. The same thing can happen with high-voltage electrical lines and equipment. If you get too close, electricity can find a path through the air to your body, especially if you are standing on the ground or touching something that can conduct electricity.

That’s why electricians use insulated tools and keep a safe distance from high-voltage equipment. Even household outlets can cause small electrical arcs if you plug in something improperly or have damaged wiring.

Why is it important not to break the ground pin off a power cord on a tool or appliance?

The ground pin—the round third prong on a plug—is there for safety. It provides a path for electricity to go safely into the ground if something goes wrong, like a loose wire inside the tool or appliance.

If you break off the ground pin, that safety path is gone. If the tool has a short circuit, electricity could travel through the metal parts of the tool—or even through you!—causing a dangerous shock. That’s why it’s important to always use three-pronged plugs with properly grounded outlets.

Why don’t birds get electrocuted when they sit on an overhead power line?

Birds can safely perch on power lines because they are only touching one wire at a time. Electricity moves when there’s a difference in voltage between two points, and since the bird’s whole body is at the same voltage as the wire, there’s no reason for electricity to flow through it.

However, if the bird were to touch two wires at once, or one wire and a metal pole or transformer, electricity would flow through its body, and it would get electrocuted. That’s why power line workers wear special insulated gear and follow strict safety rules when working around electrical lines.