In 2017, about 4.03 trillion kWh of electricity was generated in the United States alone. The average home uses about 10,400 kWh in a year. We've got electricity on a grand scale here, without a doubt. With all those electrons flowing around freely, it's no wonder there are so many electricians out there and there always seems to be a demand for more. Having an understanding of and respect for how electricity works is an important skill and will likely remain so for a very long time to come.
Your average electrician has to understand a lot of things. Just the math alone in figuring out resistance or power based on current or capacitance sounds utterly daunting to a layman, not to mention all the codes and standards that need to be adhered to when doing wiring and installations in a home or commercial environment. A person could take years to master it all. But we don't need you to be a master! If you think you know the basics, the stuff you might need to understand for an electrician's entrance exam, now's the chance to show your stuff. Plug yourself into this quiz and prove you've got what it takes. Will it be shockingly easy ... or not?
What law states that the current in a conductor is proportional to the voltage and inversely proportional to the resistance?
Ohm's Law was named for George Ohm, who studied electrical resistance way back in the years 1825. Even though it seems like one of the most basic tenets of the study of electricity today, critics really hated Ohm for suggesting it back in the day. Go figure.
What should be used to put out an electrical fire?
CO2 or a dry chemical extinguisher
You never want to use water to handle an electrical fire, as water conducts electricity too well and can cause more damage as well as putting people in the area in harm's way as well. The best option is a CO2 or dry chemical powder extinguisher.
A multimeter doesn't have that name for no reason - it measures multiple things. A multimeter is capable of measuring current, voltage and resistance. They're remarkably common items and can be picked up at a hardware store for just a few dollars.
Of what material is electrical wiring in homes normally made?
Copper is far and away the most common material for wiring in North America. Other metals conduct electricity just as well, and some will do an even better job, but because of how resilient copper is, how well it conducts and the relative cost, it's the popular choice.
What do you call a device that can raise or lower voltage?
A transformer is a device that uses coiled wire to transfer electrical energy by way of a changing magnetic field. It transfers electric current from one circuit to another at a constant frequency while allowing the voltage to increase or decrease.
Ohm s a measure of electrical resistance. It was named for German physicist Georg Simon Ohm. The dictionary says it's a unit of electric resistance equal to the resistance of a circuit in which a potential difference of one volt produces a current of one ampere. Fun!
Tamper-resistant outlets should be installed according to according to the National Electric Code. They prevent children from inserting foreign objects like paperclips into the outlet and injuring themselves.
What do you call the path from an energy source through wires or devices and back to the energy source?
A circuit is the path energy travels, like a full circle back where it came from. This is easily visualized with a battery hooked to a light bulb by wires. It creates a circle with wire from the positive end of the battery to the bulb back to the negative end of the battery.
A typical outlet has two slots and then a small, half-oval opening. What's that half oval for?
The large slot in an outlet is neutral while the smaller one is hot. the half oval on the bottom is the ground. Older outlets will likely not have a ground, but that makes them more prone to shorting out.
A capacitor stores an electric charge, kind of like a battery in the sense that it will hold and transmit electrons along a circuit. A capacitor's ability to hold a charge is called its capacitance, and the unit to measure that capacitance is the farad.
In an effort to make things easier and safer, wires are meant to be color coded and a ground wire should be green. Wiring a house with incorrect wire colors could prove incredibly dangerous for another electrician.
Direct current is current that flows in one direction, like from a battery. When power first started to be used for lighting in homes, it was direct current. Alternating current proved to be a superior choice and eventually replaced it.
What do you call a substance capable of transmitting electricity?
Any substance that can transmit electricity is a conductor. This is obviously something like copper wire, but the reason we need to be cautious around electricity is that humans can also work as conductors.
A mogul base is a kind of large light bulb base. Because a larger base generally means more power, the bulb that fits with a mogul base is usually pretty big, like the sort of bulb you might find in an industrial setting.
A megger is another name for a megohmmeter, and it's used to measure insulation resistance. The resistance of insulation like cable jackets needs to be measured when things are installed and then as part of regular maintenance to make sure they are still working normally.
How many amps does it take to cause heart failure in a human?
You would be able to detect 0.001 amps running through your body. 0.009 amps would shock you enough that you would pull away. At 0.5 amps, you run the risk of heart failure and if you get up to 1.5 you can literally burn your organs.
Watts are the unit of measurement used for electrical power. It's defined as a derived unit of 1 joule per second. It's named for Scottish inventor James Watt. During your average workday, you sustain an output of about 75 watts.
Electrical current is measured in amperes. The ampere is usually abbreviated into "amps" and is named for Andre-Marie Ampere. It's proportional to the number of electrons flowing through a conductor past a given point in one second.
What do you call the amount of flowing electric charge in one second?
Current is the flow of electrical charge. In practical terms, this is the flow of electrons moving through something like the copper wires in your wall. In a nutshell, that's what electricity in your house is, just a bunch of electrons in wires.
Roughly how much energy does a modern refrigerator use?
A modern refrigerator uses about 350 kWh per year, as an energy-efficient appliance. In the early '80s, a fridge might have used around 1400 kWh a year. Neither of those figures includes an ice maker, mind you.
What renewable energy source is the most cost-effective source of electricity?
Solar power is remarkably cost-effective for both businesses and individual homeowners. A solar system will pay for itself. on average, after about 8 years. Many cities also offer rebates and incentives to switch to solar, further increasing the value.
Equalizes the voltage potential between conductive systems
Bonding is sometimes confused with grounding, but it serves a different purpose. Bonding equalizes the voltage potential between conductive systems. This can stop you from being the path a current takes between systems, and can also prevent lightning strikes from causing fires.
Tin or a tin alloy is often used inside household fuses as opposed to copper for a very specific reason - tin has a lower melting point than copper and the wiring in the fuses is meant to melt if it overheats, thus safely breaking the circuit
In what kind of current does a Wattmeter measure power?
AC and DC Current
A wattmeter measures current in alternating current (AC) and also direct current (DC). It measures the total power across a circuit. As you might expect based on the name, it measures the power in watts.
About how much of the electricity generated in the US comes from nuclear plants?
About 1/5 of the power in the US is generated in nuclear power plants. Nuclear fuel undergoes a fission reaction, which in turn heats water. The heated water generates steam and that steam moves turbines to create electricity.
How much of the energy in a typical light bulb actually creates light?
A mere 10% of the energy that flows through a traditional light bulb actually produces any light. The other 90% becomes heat that the bulbs give off. That's why newer, energy-efficient bulbs are a much better option.
What kind of outlet should be protected by an arc circuit breaker?
A bedroom outlet needs to be protected by an arc-fault circuit interrupter that breaks the circuit when it detects an electrical arc. It's required in bedroom outlets as a life-saving measure to prevent deadly bedroom fires.
A coulomb is a measurement for electric charge. It's equal to the amount of electricity conveyed in one second by a current of one ampere. It was named for Charles-Augustin de Coulomb, who also got a law named for himself. Good job, Charles!
Technically there's a different between electrocution and electric shock. What is it?
Shocks are less powerful.
Shocks don't cause permanent damage.
Electrocution is always fatal.
Electrocution is when electricity is used to execute someone.
Electrocution is a portmanteau word that originally meant "electrical execution." It was literally meant to refer only to people executed by electricity. In time it just came to mean any kind of electric shock.
At a certain height off the ground, an outlet is not required to be tamper-proof. What's the height?
At 5.5 feet and above, an outlet is not required to be tamper-proof. Since a tamper-proof outlet is a safety precaution for children, at that height it's safe to assume most children won't accidentally come into contact with it.