Its almost over.  I can see the fat lady going me-me-me-me-me

First time.  Let's see if it dies.

Not happening today Bunky.  The fat lady even sang and this thread is still going.

The sexual tension between this fork in my hand and the power outlet in front of me is maddening....

zaaaapppppppp

Remember the Vincent Price commercials selling bug zappers?

Go get em SPARKY!

That looks like a Macbook, anyway. Good reason to stop posting!

Just remember, where ever you go, there you are.

Attached File

So here is the deal: Electrons that flow through a conductor in an AC system alternate back & forth at a rate that is based on the frequency. This is measured in amperes, or amps. An amp is equal to 6.28x10 to the 18th electrons flowing past a given point per second. Think about that. That is a metric fuckton of little negatively charged jobbers being transferred from valence ring to valence ring of the atoms within the conductor.

As a result, work is done based upon the design of the load but heat is also created within the conductor. This is due to friction. As an example, do the Mr Miaggi wax on wax off hand rub thing. The more vigorous you wax it off the hotter your hands get. So from this we can see a limitation of any conductor is heat. The more electrons flowing the larger the conductor needs to be. A 12 gauge copper conductor can, per the NEC code book, can have no more than 25 (I think) amps flow through it. However, it is only allowed to be protected by a maximum 20A OCPD (overcurrent protective device) but that is a different discussion.

A 500kcmil (kilo-or thousand- circular mil) conductor can have up to 380A flow through it per the NEC. This is all based on the 75degree Celsius scale in table 310.15(B)(16). This table was formerly 310.16 up through the 2008 NEC & was changed in the 2011 edition. Reason being is that tables in the NEC are numbered based on the section that refers you to said table. There never was a Section 310.16. But back to the amperage thing...

So, this 75degree scale is what I personally always use, as opposed to the 90degree scale, because damn near all lugs on a breaker are rated for 60/75degrees but not 90. You see, any circuit rating is only as strong as its weakest link. If a conductor is sized based on the 90 scale but the lug isn't, than the lug will potentially get hotter than it is rated for and fail. Now some of you are saying that there are lugs rated for 90degrees and you would be correct but many circuit breakers are not made with these lugs. Always check the temp rating of your termination lugs. Look for a marking like 'AL9CU' or 'CU9AL. The letters mean that it is rated for both copper & aluminum while the 9 means that it is 90degree rated. If the '9' was a '7' than it is only rated for 75degrees.

Okay, where was I...oh yeah ---> amperage flows from the source, through the load, & than back to the source. Amperage, or current, should NOT flow within the grounding system. All of the green wires in the system are there for safety. There are different names for different parts of a grounding system based on where it is within the system. The part that makes the physical connection to the earth is the grounding electrode. 250.52 allows for the following types of electrodes: rod, pipe, plate, ring, concrete encased (commonly called a ufer, named after some guy named Ufer because he founded the use of this type of electrode), steel structure of a building, underground metal water pipe, and probably a couple more that I can't remember right now. There are restrictions to material type, install method/rules and such but I ain't going there right now.

The conductor that connects this electrode to your panel/switchgear is the grounding electrode conductor. This is sized based on the equivalent size of the service entrance conductors and isn't required to be larger than 3/0 ( that's 3-ought or 000). You see, on the American Wire Gauge scale the larger numbers are smaller wires and as the wire gets bigger it's AWG number gets smaller. Example being numbers going as such:12, 10, 8, 6, 4, 3, 2, 1, 0(1/0 or 1-ought), 2/0, 3/0, and finally 4/0. From here, the size is simply the circular mills of the conductor starting with a 250kcmil, 300, 350, 400, 500, 600, 750 and so on up to 2000. 750 is a big bitch, I couldn't imagine pulling 2000's!!! Who of you still call a 500 like this---> 500MCM? This is old terminology that means the same thing as kcmil. The first M is the Roman numeral for 1,000 just like k is the metric prefix. The CM than means circular mils.

What is this unit of circular mils that I speak of? It is an area measurement specific to conductor sizing. A mil is a linear measurement equal to one/thousandth of an inch. A circular mil is mils times mils. This formula is not like the area of a circle measurement which is (pi)(r)(squared). Why does the area of s conductor differ from the area of a circle you ask? I ain't sure except to probably get to a much more specific number for it value. A 12awg is 6530 mils, a 10awg is 10,380 mils & I don't remember any others right now. We can talk raceway fill (based on area) and box fill (based on volume) but that's a whole different discussion so back to grounding.

The conductor that connects the grounding conductor to the grounded conductor at the service is the main bonding jumper (system bonding jumper at a seperately derived system such as a transformer). This can be a wire, bus bar, or screw depending. I'm sure you are wondering what this 'grounded' conductor is that I spoke of? This is the system conductor that is intentionally grounded & is commonly called the neutral. It isn't always a neutral and could be a corner of a corner grounded delta but... This neutral is identified by white or gray insulation or black insulation with white or gray tale at its termination points. The neutral IS a normally current-carrying conductor. In your house on a 120v ckt the black, ungrounded 'hot' wire is where the current starts to flow through the circuit conductor toward the load. The neutral is the return path for this current back to the panel to the neutral bus, through the grounded service entrance conductor and finally back to the source or transformer winding(s).

The grounding conductor is the conductor that is continuously performing the grounding, or making the connection to, the metal non-current carrying parts n pieces of all the things. There should NOT be any current flowing on this conductor. This is the green, or bare conductor. What is the purpose of this grounding conductor? It's three fold actually: to put all non-current carrying metal parts at the same potential as the earth (remember the grounding electrode, grounding electrode conductor and main bonding jumper), to perform bonding duties & to be able to safely carry ground fault current to help facilitate the operation of the OCPD. Ground faults are typically high current faults that can be 1,000's of times higher than normal current values. During a ground-fault LARGE amounts of current flow from the source, through the circuit breaker, through the grounding system and back to the source. This is why the secondary windings of a transformer are grounded & why the main bonding jumper is what it is. The main bonding jumper provides a path for this fault current to flow back to the transformer. The circuit breaker says OH SHIT THIS IS WAY TO MUCH CURRENT!!!!! I NEED TO OPEN MYSELF UP!!!! Hopefully it does, as opposed to blowing the fuck up. You see, any OCPD has a rating called its AIC (amps interrupting current). This is the amount that an OCPD can safely have flow through it before it blows the fuck up.

Gear has an SCCR rating (shirt-circuit current rating). Kinda the same but more specific to the bussing in the gear. The higher the rating the more, stronger the bracing for the bussing. I mentioned that heat is created when current flow but one more thing happens. A magnetic field is created when current flows. Copper is non-ferrous (can't be permanently magnetized) but can become an electro magnet. Basically to magnetize a material you need to align many many of the atoms within it. During current flow some of the atoms, specifically electrons, all flow the same direction and work together so that their individual magnetic fields add to each other. The higher the current, the stronger the magnetic field. High faults can easily cause wires to slap around in conduits or for bus bars to be physically attracted to each other (bent like a motherfucker) until they possibly touch each other and blow the fuck up!!! KA-FUCKING BOOM!!!!

I can get deeper into this, explain how transformers and motors work, what voltage, resistance & power are, how to bend conduit in every way, and a bunch of other shit but I need to stop typing so I can get back to chugging my Keystone Lights.

REPORTED for wasting site resources.

But aren't site resources simply electrons?  It seems if you are discussing electrons on the internet in a forum, you are merely rearranging the existing electrons and not destroying them.

All the time.

Will this thread die now?

This is GD. Facts, reason and logic do not apply.

Ok, can someone explain how that buck took that upper off the lower?  I mean the buck aint got no thumbs!!!

If this does not kill this thread then nothing will.

Does the deer have some doh

Yea two bucks!

What does a cow do on Friday night?
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Go to the MOOvies!

What do you call a cow with no legs?
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Ground Beef!

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Took him that long to see a problem?

That right there is some funny stuff!!!!