# Quick Course in Electricity



## Herb Stoops (Aug 28, 2012)

Study this and then take the test for journeyman.
Herb


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## DonkeyHody (Jan 22, 2015)

That's well put. I've always used the analogy of water in a pipe, which I can understand intuitively. But when trying to use the analogy with others, I find that a lot of people, even a lot of engineers, don't have an intuitive understanding of electricity in a circuit or water in a pipe either.


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## JFPNCM (Dec 13, 2009)

Andy:

Good points. The real difference is that water leaks, electricity doesn't.


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## Cherryville Chuck (Sep 28, 2010)

That's always the analogy I've used too Andy. Water is like the amp and the pipe pressure is like the voltage and pipe size and elbows and changes in diameter is like the ohm. There are a few correlations to it such as adding a wire to a circuit is like adding a tee to a water line and going up a wire size or pipe size makes it flow easier.

The problem with trying to explain lots of things I've noticed has nothing to do with how simple it is. It has to do with how complex the person you are explaining it to thinks the problem is. The more complex they think it is, the less likely they are to understand your explanation.


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## Herb Stoops (Aug 28, 2012)

Cherryville Chuck said:


> That's always the analogy I've used too Andy. Water is like the amp and the pipe pressure is like the voltage and pipe size and elbows and changes in diameter is like the ohm. There are a few correlations to it such as adding a wire to a circuit is like adding a tee to a water line and going up a wire size or pipe size makes it flow easier.
> 
> The problem with trying to explain lots of things I've noticed has nothing to do with how simple it is. It has to do with how complex the person you are explaining it to thinks the problem is. The more complex they think it is, the less likely they are to understand your explanation.


Your analogy works for airflow in Dust Collection too, Chuck.
Herb


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## MT Stringer (Aug 15, 2012)

I have always had trouble with electricity. Even spending 33 years working in operations at a chemical plant. The electrical part was difficult to understand, until the lights went out!

Piping and flows were no problem. If need be, I could always follow the piping to see where it started and where it ended, but not the electrical part. Mostly I was happy when the emergency generator started during the monthly test.


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## DaninVan (Jan 1, 2012)

Everybody wishes they _HAD_ paid attention when the HW tank starts leaking...


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## TenGees (Sep 12, 2012)

JFPNCM said:


> Andy:
> 
> Good points. The real difference is that water leaks, electricity doesn't.


Corona discharge?


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## Herb Stoops (Aug 28, 2012)

TenGees said:


> Corona discharge?[/QUOT
> When I lived next to the power line right of way, You could stand under the power lines and hold a florescent tube overhead and it would light up.
> 
> Herb


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## artman60 (Nov 22, 2015)

What’s black, crisp, and hangs from a chandelier? An inept electrician.


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## Gene Howe (Jul 10, 2007)

Herb Stoops said:


> TenGees said:
> 
> 
> > Corona discharge?[/QUOT
> ...


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## JFPNCM (Dec 13, 2009)

Paul:

Appreciate the note on the corona discharge. Forgot about that one.


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## TenGees (Sep 12, 2012)

A college professor of mine had worked with hydro. He told us that cows near hydro towers always stand with their side toward the towers. Standing facing or facing away causes a greater voltage difference between their legs which would be uncomfortable.


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## TenGees (Sep 12, 2012)

JFPNCM said:


> Paul:
> 
> Appreciate the note on the corona discharge. Forgot about that one.


I took electronics in school. When soldering the high voltage on old style TVs if you left a 'point' in the joint, it could 'leak'. A rounded joint was necessary. You could hear a really bad one fizz.


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## Cherryville Chuck (Sep 28, 2010)

Gene Howe said:


> Herb Stoops said:
> 
> 
> > Just beyond our back property line there are those high voltage power lines. And, what you say is true. We tried it. My BIL was a big gear electrician before he retired and moved to the ranch next to ours. He toyed with the idea of setting some sort of device under them and getting free power. He never did it. Couldn't figure out how to hide it.>
> ...


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## roxanne562001 (Feb 5, 2012)

My electrical engineering professor always used the analogy that resistance was like the A holes going the wrong way in the mall at Christmas time. Diagram depicts it well. LOL


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## DesertRatTom (Jul 3, 2012)

Since the electrical folks are reading this, perhaps someone could explain how 220 circuits are configured and what phase means in a 220 circuit?

When I was in high school, we did a production in the gym,and I rewired from the box to run our dimmers, but I can't recall how I did it.


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## BrianS (Nov 7, 2004)

TenGees said:


> I took electronics in school. When soldering the high voltage on old style TVs if you left a 'point' in the joint, it could 'leak'. A rounded joint was necessary. You could hear a really bad one fizz.


I've always found that once you let the smoke out of anything electrical, it just didn't work the same....


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## Knothead47 (Feb 10, 2010)

If I recall, I stayed at a Holiday Inn Express, 220 had four wires- black (hot), red (hot), white (neutral), and green (ground). The black and red supplied the current to add up to 220. Used to do R&D for two appliance manufacturers. Now single phase and 3 phase are a different ball game as we didn't have anything with those requirements. I do think it has something to do with the alternating current. Anyone else help out here?


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## DaninVan (Jan 1, 2012)

Tom; It'll take more electrical knowledge than I have...but basically, when we state an AC electrical voltage what we're actually referring to is the median voltage through the sine wave representing the energy as it flows from the generator
120v is a single phase, 240 is the total of the two phases...basically a figure 8 sine wave (not shown below).
3 phase is a bit different... 208V...see the diagram below representing the energy coming off the generator's windings. Again the number is the Root Means Squared (RMS).


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## DesertRatTom (Jul 3, 2012)

Thanks Dan. That helps a lot. Looks like a motor would be near the peak of the voltage at all times with 220/3 phase, vs half the time with 110 single phase. So Red & Green wires are both hot, but in 110 you only use the black, plus neutral. So, does a 220 motor have separate windings for each hot line?


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## JOAT (Apr 9, 2010)

Mechanical I can figure out. Electrical, might as well be magic, I don't understand magic either.


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## DaninVan (Jan 1, 2012)

*Can't Touch This...*



DesertRatTom said:


> Thanks Dan. That helps a lot. Looks like a motor would be near the peak of the voltage at all times with 220/3 phase, vs half the time with 110 single phase. So Red & Green wires are both hot, but in 110 you only use the black, plus neutral. So, does a 220 motor have separate windings for each hot line?


Green isn't a conductor,Tom. Here, in N.America, it's always the ground wire, or in some cables it's bare copper...in theory it shouldn't actually be carrying any current.
single ph. 120V black & wht.
2 ph. blk red @ wht.
3 ph blk, red, blue & wht.
In 240V (220V) electric heating ccts. they use a cable with red and black conductors, no white neutral required. If it's Non-metallic sheathed cable (Loomex/Romex etc) the outer nylon sheath is red in colour so you know that's what the cable is being used for. In older wiring the cable is supposed to be identified with red marking every few feet. 
If you have an electric HW tank, the cable could be #12 ga with the red outer covering, if it's maybe 15 yrs. or newer(?)...

"So, does a 220 motor have separate windings for each hot line?"
[/QUOTE]
I think you're correct but I'm going to defer to anyone who actually works with this stuff...


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## Cherryville Chuck (Sep 28, 2010)

Further to what Dan said, in 220 - 240 volt circuits no neutral is necessary unless you have an auxillary piece of equipment that needs it. For example an electric stove or oven usually has a light, timer, and maybe a plug in for a toaster or such. In that case you also need the neutral wire and the circuit works by tapping into one of the two hot legs and connecting the other side of the device to the neutral.

If you are connecting a motor, as to a tool in your shop, it only needs the red, black, and green. All electrical devices where the case or frame has the potential to be energized if there is a short must be grounded. That's the only time the ground wire should ever carry current. The black and red act as return wires for each other so no white is needed. You can switch just one wire in a 220-240 volt circuit because of that.

I also think that the motor would have 2 sets of windings but I'd let an expert confirm that.


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## roxanne562001 (Feb 5, 2012)

Its called magic smoke. Once you let it out there is no more magic


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## CAD-Man (Apr 28, 2013)

I worked in the electronics industry for almost 30 years. I started with tube gear in the 1970's (Military Gear) and finished with Field Programmable Gate Arrays (FPGA's) in the early 2000's. The one thing I learned that will always stick with me is what comes out of most electronic devices will burn you, what comes out of the wall will kill you. I have been zapped by 25,000 volts at a few micro amps and it really smarts but I have seen people knocked flat on their behind (and that's being lucky) from 115 Volts at 15 amps.

When I was a kid, my father rewired the fuse box ( the old screw in fuses) to a circuit breaker style box. My dad wore a belt with another belt hooked up to it. My mom would stand behind him holding the second belt. He told her, "if you see me shaking" pull hard on the belt. At that time, I thought, How Brave, later I found out, How Stupid. That would have been 220V at 50 to 100 Amps.

CAD-Man


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## harrysin (Jan 15, 2007)

BrianS said:


> I've always found that once you let the smoke out of anything electrical, it just didn't work the same....


That simply proves that electronics, especially transistors and integrated circuits work using smoke, once it escapes the device no longer works!


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## DaninVan (Jan 1, 2012)

!...I know this from personal experience.


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