Electrician U

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Electrical power is often expressed in two units, Watts and VA.  Wattage and Volt-Amps rather, get misused because many people do not understand the differences in them and when they should be used.  In this episode I break down the differences in the two terms and how they relate to one-another in the electrical industry.Wattage (Watts)

Most people use the word wattage or watts on a pretty regular basis when talking about power consumed in an electrical circuit.  If we have a 75-watt light bulb, we might say that this bulb is “burning” at 75-watts.  This is because this bulb is rated at this wattage based on the materials inside of it.  There is a filament (coil of wire) inside the bulb that has a very specific resistance.  When connecting 120-volts across this filament a certain amount of heat and light is produced because 0.83 amps of current are flowing through the filament. 

The heat and light coming from the filament is technically waste, or “power loss” – however it’s not REALLY lost.  The light, and sometimes heat, is a wanted effect of running current through the high-resistance filament.  In fact, that is the entire purpose of it’s design.  We want that filament to be crammed with current so much that it starts to glow red-hot.  This light bulb is consuming 75-watts of energy when it is turned on. Wattage is the actual power consumed, or “true power” that is recorded by the electrical meter and charged for by your utility company.

Volt-Amps (VA)

Volt-Amps are very similar to Watts, but are not the same thing.  A volt-amp is a calculated value, or assumed value that represents how much “theoretical power” should be present to be consumed.  Think of it this way: In the example above we said the Wattage of that lightbulb was 75-watts.  Well if we take the voltage (120v) of the circuit times the amperage (0.83amps) we get 75-volt-amps.  So in this light-bulb, the VA or volt-amps are equal to the wattage being consumed.  But that’s not always the case.

Say we have a 75kva transformer in a building.  75kva is equivalent to 75,000 volt-amps.  This could be because the transformer is a 480-volt transformer that can handle 156-amps of current flowing into it, or a 240-volt transformer that can handle 312-amps of current.  Either way by multiplying the voltage by the amperage we get the calculated VOLT-AMP rating of the available power present at the transformer. (480v x 156a = 75,000 va or 240v x 312a = 75,000 va)  We cannot simply say that this is a 75,000 watt transformer or 75KW transformer because the 75,000 figure represents a calculation for how much power is available.  This is called the “apparent power,” and must be represented in Volt-Amps (VA).  If we said this transformer was a 75,000 watt transformer then we would be saying this transformer will burn 75,000 watts of power when turned on, which is simply not true.  A transformer needs to provide a certain amount of power, that on the primary side is capable of producing a certain amount of power, and on the secondary is capable of producing the exact same power but with different voltage/amperage.

Remember the volt-amps are looking at the calculation of the circuit to see how much “apparent power” S

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This Husky 22″ Rolling Tool Bag is a beast! I was fortunate enough to have Husky send it to me to try out, and I’m really in love with it. It’s a bit larger than I was anticipating, but the capacity it has to reduce several bags down to one is impressive. I’ve used other… Continue reading Tool Review – Husky 22 inch Rolling Tool Bag (Tote)

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Resistance is one of the most crucial aspects of an electrical circuit.  Along with Voltage and Amperes, Resistance plays a major role in how a circuit operates.

In this episode talk about how electrical current travels through a resistive load, and how changing voltage or resistance can effect the amount of current flowing through a circuit. Resistance is a very important element of an electrical circuit.  As electricians we use the term impedance more than we use resistance, as impedance refers to AC circuits – whereas resistance refers to DC.  However either way we’re talking about a physical object that is used to stand in the way or oppose electrical current.

Resistance in an electrical circuit is most often a complex coil of wire.  When a difference of potential (voltage) is connected across a resistance (load) current will flow through the circuit.  Without the load present, so much amperage will flow that it can cause serious harm to the system.  So resistance helps to slow the current down, and make it useful rather than harmful.

We cannot simply change amperage with a dial, but we can control the voltage and the resistance so in effect the amperage will change by altering either of these two values.  Ohm’s Law shows us that there is a very specific relationship that current has with both voltage and resistance.

If you keep a load the same, meaning that the resistance stays the same, but increase the voltage – the amperage will also increase.  This is because voltage and amperage are directly proportional to one another.  Conversely if you keep the voltage the same, but increase the resistance, the amperage will decrease.  Also if you keep the voltage the same but decrease the resistance, the amperage will increase.

Resistance and Impedance are both methods of slowing down current enough for it to be usable.  When current is unimpeded (meaning no resistance in it’s way) it can create an immense amount of heat, which may melt the insulation off of the wires or cause the wires to start welding themselves together.  This is a very dangerous and dramatic event when it does happen.

So putting a coil of wire in the middle of the circuit slows the current down to a usable level.  Most appliances on electrical circuits operate because there is a coil of wire on the inside of them.  When current leaves the source and travels into the appliance, it has to travel through instructors and capacitors on its way out of the appliance and back up to the source.  In an AC circuit the direction alternates this happens 60 times per second.  This works the same way in a standard DC circuit, except with the DC circuit there are resistors, so we call these circuits resistive circuits.

Impedance in an AC circuit has 2 parts that make it up.  Inductive reactance and capacitive reactance.  I will get more into these in a later video, but for now just understand that there is a definite relationship between a capacitor and and inductor in how they affect current in an AC circuit.  An inductor and a capacitor act to cancel some of the effects of each other out if they are both introduced in a circuit.  However if only one is in the circuit it will act opposite than the other one would.  For example if an inductor is in the circuit, you would have an inductive circuit that would ma

Want to learn more about becoming an electrician or mastering the craft? Visit ElectricianU.com for courses, resources, and everything you need to succeed! 

Resistance is a very important element of an electrical circuit. As electricians we use the term impedance more than we use resistance, as impedance refers to AC circuits – whereas resistance refers to DC. Resistance and Impedance are both methods of slowing down current enough for it to be usable. When current is unimpeded (meaning… Continue reading What is Resistance/Impedance (Ohms) – Why electricians need to know it

A lot of green apprentice electricians ask about how panels work, and more specifically what the roll of the circuit breaker is. Some guys think that breakers “put out” electricity, or that they “send” a certain amount of amperage to a load from the panel. This is not how it works.

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A lot of green apprentice electricians ask about how panels work, and more specifically what the roll of the circuit breaker is.  Some guys think that breakers “put out” electricity, or that they “send” a certain amount of amperage to a load from the panel.  This is not how it works.

To start out, an electrical panel is simply a place where all of the many loads throughout the house meet up with the main feeders or service entrance conductors coming into the building.  It’s essentially a large junction box.  But rather than just joining all of the branch circuits and feeders to the service entrance wires, we put breakers in between each circuit to protect that circuit from any problems that may arise.

To understand how electricity flows we must understand the idea of “difference of potential.”  When a difference of potential energy exists between 2 wires, connecting those wires together will allow current to flow through them.  It will be extremely dangerous due to the amount of electrons flowing through the circuit, and you will most likely see an explosion happen in front of you.  So don’t do this.  Electricity is extremely dangerous in a circuit without a load or impedance in it.  So to make electricity useful, we have to introduce a load to the circuit.  A load is essentially a resistance.  It is something that slows current down.  Loads can also be inductive/capacitive and therefore reactive rather than resistive, but we won’t get into the semantics of this topic, in this post.  For now just understand that for electricity to be useful it must be slowed WAY down.

When a circuit has a proper resistance on it (say a toaster or lightbulb), the current slows down to a usable level and does not allow an explosion to happen.  But sometimes parts wear out and when this happens current can rise to dangerous levels (essentially speeding back up).  When this happens we want to have a protective device in place to disconnect the circuit so it doesn’t melt or cause a fire.  Enter the circuit breaker.  (By the way…fuses are very similar to breakers and serve the same function.  More on that in another episode)

A circuit breaker does not “output” any power.  It simply allows current to flow through it until that current gets to a dangerous level, in which case it automatically opens or “trips” the circuit.  A breaker is essentially an automatic switch.  It can be manually opened or closed (turned on or off), or it can automatically trip by sensing how much current is flowing through it.

Breakers “sense” current flow by a small electromagnet inside of the device.  For instance, a 40 amp breaker will have an electromagnet inside of it that when more than 40 amps flows through it, magnetically (mechanically) pulls the contacts apart – stopping current from continuing to flow through the device.
 

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Want to learn more about becoming an electrician or mastering the craft? Visit ElectricianU.com for courses, resources, and everything you need to succeed! 

Synopsis: The hammer drill and impact set from Dewalt was one of the first tools I got to use as a part of the #THDproSpective program.  I’ve traditionally been an 18v Makita guy for the past decade, so I was really excited to test out Dewalt’s 20v stuff. I took a poll recently on my… Continue reading TOOL REVIEW – Dewalt Combination Hammer-Drill & Impact Driver Set

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Electric current is one of the hardest things to wrap your head around when you’re first getting into the electrical trade.  Many apprentice electricians get confused with the difference between current and amps.  Well, that’s because people talk about electrons and charges and interchange the terms without really knowing what the difference is.

Electric current can be thought of like water current or wind current.  Its a flow of an invisible force that can have tremendous power.  In water current you have movement of oxygen and hydrogen molecules.  In air current you have movement of oxygen, nitrogen, and hydrogen molecules.  In electrical current you have movement of electrons in copper molecules.  The movement of these electrons creates a magnetic current.

Electrons move about in many directions normally, but when a negative charge is introduced to a negative electron, they repel each other.  Viola!  We have movement.  When we put a negative charge on one side and a positive charge on the other, we have a direction or path for the electrons to travel.  This path is never straight, because the very nature of electrons is that they traverse their atom in a circular fashion.  So when they leave their orbit, they enter another orbit and sort of swing from atom to atom, always randomly.

The more force you put behind a current the more “straight” the electrons will travel…relatively…but still never in a straight line.  The more force you put behind current, as well as the amount of current flowing through a conductor, the more heat can build up.  When more current passes through a conductor than it can handle, it will start to glow red hot (like a light bulb filament or a toaster element).  This is overloading the conductor, and depending on the material it can melt or cause a fire over enough time.  This is why we install fuses or breakers on electrical circuits.  These fuses/breakers can detect how much current is flowing through a circuit and will disconnect the circuit before a dangerous situation arises. 

There is a lot more to know about how current works, and some of the different things it does when introduced to certain components.  But for now this is a crash course on the basics.  If you have any questions feel free to comment below.

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**Disclaimer – These videos are for training purposes alone, all work done on electrical systems should be done by a licensed and insured electrical contractor.  If you are not an electrician, do not attempt any of the work you are seeing in these videos.**

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Want to learn more about becoming an electrician or mastering the craft? Visit ElectricianU.com for courses, resources, and everything you need to succeed! 

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Automatic circuits work on the philosophy that some external/automatic switch turns power on and off to a circuit.  This can be a photocell or timeclock that controls a set of relays or contactors which allow or disallow current to flow in a circuit.

A photocell takes in light from a photovoltaic eye, and opens/closes a coil inside the photocell.  It does this completely independently of human interaction.  A timeclock has a constant clock that ticks and spins a dial which trips a lever to engage or disengage a circuit to allow current to flow through it.

There are some dangers associated with working on automatic circuits.  Chief among them is the knowledge that at a certain time this circuit may become energized while you’re working on it. If you’re working on a parking lot pole light at sundown and a photocell decides to kick on because it’s no longer sensing photons in it’s eye, the circuit could turn on while you’re hand is in the hand-hole.

Always shut power off to a circuit before you work on it, especially when working on automatic circuits. The tricky part about automatic circuits is knowing which breakers to shut off.  Most automatic circuits have a photocell or some sort of timer that controls the circuit.  We call this circuit the “control circuit.” By shutting this breaker off, the photocell or timeclock will no longer engage, but this does not mean that the other circuit feeding the light/load is off.  There are separate circuits that leave the panel, go to a contactor or relay, then go out into the field.  These breakers could still be on if you have a normally closed contactor or relay feeding the load.  You should always test the circuit before working on it, but taking the extra time to shut the load circuits off as well as the control circuit is a great habit to get into.

In this video I show how contactors and ice-cube relays work, and how to wire them.  I also explain the difference between normally-open and normally-closed contacts.

If you like these videos please subscribe, and click the notification bell to be notified every time I do a new video.  Also check out the Electrician U facebook page or find me on instagram @electrician_uhttp://electricianu.com/wp-content/uploads/2019/07/Episode15-SCHEMATICS-AutomaticCircuits28Contactors2CRelays2CPhotocells2C26Timeclocks.mp3

Want to learn more about becoming an electrician or mastering the craft? Visit ElectricianU.com for courses, resources, and everything you need to succeed! 

Electric current is one of the hardest things to wrap your head around when you’re first getting into the electrical trade.  Many apprentice electricians get confused with the difference between current and amps.  Well, that’s because people talk about electrons and charges and interchange the terms without really knowing what the difference is.