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Old January 21, 2017   #20
Worth1
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Join Date: Feb 2006
Location: Den of Drunken Fools
Posts: 38,539
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Alright on with the show/class so to speak.
If at any time I am wrong and there is an expert here reading feel free to interrupt and set me and us straight please.
I am at a wee bit of a loss as of where to start.

We will start with a common misuse of a word that drives me nuts.
That is the term the wire must have a short in it.
This is used most often when something doesn't work.
No that is called an open circuit not a short.
A short is when the wire touches each other or ground before it gets to the load.
We will hope this trips a breaker or burns out a fuse before the wire starts glowing red and burns the house down.

Next, the misconception that if you touch the white neutral wire you wont get shocked.
Hog wash, been there done that.
Next rule of thumb.
Electricity follows the path of least resistance.
If you become that path you are going to get hit big time.
Or you just might become part of the load.

I have mentioned load two times now so what is a load?
A load is anything be it appliance or light fixture and even you that uses up the currant in the supply.

Lets look at it this way.
You can carry so much weight/load but instead of pounds we will call it amperage/amps.
The below is just an example not what this stuff draws.
The toaster oven lets say draws 5 amps the blender draws 5 amps the refrigerator draws 10 amps.
You now have 20 amps/pounds to carry.
And you can only carry 15 pounds/amps.
Something hast to give.
With you it is your legs breaking.
With the breaker it is the breaker tripping.
But before this happens your legs will get tired or your wire will start to warm up.
The warmer that wire gets the less currant it will draw.
This is why we need bigger wire or bigger legs to carry the so called load before the breaker trips.
Think of it as you having enough muscle to lift something but your bones break trying to lift it.
Muscle being wire and bones being the breaker.
Now lets compare wire length to leg/person length.
A short person with big legs can handle more load than the tall skinny person.
The same goes for wire.
That length is called resistance, resistance equals load.
So the short person uses up less load capacity than the tall skinny person before they even start to pick up the load.
This is a crazy way to look at it and I just made it up as I was writing but I like it.


Next those wires going down the street.
You will more than likely see two of the on the pole they from what I have read can carry from arounf 7,000 to 14,000 volts.
What ever it is it makes no difference.
The big can on the pole of square box on the ground is called a transformer.
This thing has a tone of wire in it coming from those big wires on the pole running down the street.
From those wires to the transformer are fuses.
Inside that transformer are wires coming from your house.
Inside that contraption are both the pole wires and your house wires wound with each other but not touching.
This is due to there being a thin insulation on each set of wires.
What happens is the electricity from the pole wire induces itself onto the house wires.
This is called induced electricity.
By way of calculations of wire sizes and length you can have a load which would be the transformer.
That energy is wasted by the power company not you by way of heat.
By calculating wire size and length you can drop the voltage from 7,000 volts to 120 volts on each one of those wires coming to your house.
Wire I remind you that never touches the main wires on the pole just real close.

Now grounding.
If you go to the first pole from your house you will see a bare wire.
You will see two insulated wires.
The bare wire is insulated at the first wood pole to your house.
It is also insulated from the steel pipe with a cap on it coming up from your house.
The cap on that steel pipe/conduit is called a weather head.
This is the weight bearing tension line that holds the other two wires.
There is now three insulated wires coming from the weather head.
One each going to those two 120 VAC lines and one connected to the tension line.
This last one connects to ground at your house inside the main breaker or sometimes the only breaker panel.

Stop Safety tip.

DO NOT take for granted that any part of the breaker panel main disconnect or that pipe/conduit is safe to touch or grab hold of.
It should be but doesn't have to be.
If for some reason one of this hot wires is just touching but not enough to cause a fault you can get hit big time.
This is not meant to scare you but just a fact.
If you ever touch any of this stuff do it with the back of your hand so you wont get locked on to it.
It shouldn't happen but by dam it can and I have experienced it in person.

Now where on earth do we get 240 VAC and 120 VAC.
In the old breaker panels they had the ground and the neutral buss all the same.
You get 120 by way of neutral being connected to that ground neutral buss and the hot connected to the breaker or fuse.
Now this breakers.
If you look at them every other one is connected to one of the two wires coming in.
If you connect one of each of the wires from you load to one of each of these breakers in line you get 240.
The ground wire goes to ground.
If you meter each wire to ground you get 120 if you meter hot to hot you get 240.

So you electric stove has not only 240 to run the burners but 120 to run the light.
The old one had a ground doing both.
The new ones have a dedicated lind just for the 120 and one for ground.
Confusing but it really isn't.
This is why the new 240 plugs have 4 prongs not three but they both end up at the same place anyway.

I am going to stop here and post this so I dont lose it.


Worth












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