[ARCHIVED THREAD] - Electrical ? (Page 1 of 2)
Posted: 10/29/2016 6:36:29 PM EDT
| If you have neutral why do you need a ground? |
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The ground is for safety only. this.. In the early days, most houses has 2 prong receptacles.. A hot, and a neutral. The ground isn't needed for operation. In fact, many of your household small appliances have only 2 prong plugs. You will also note that they have a symbol on them that denotes they are Double Insulated.. No way for power to get to the user. On metal shelled applications, they will ground the metal chassis/shell. If a malfunction allows power to get to the conductive shell, it grounds out, and trips a breaker. |
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The ground is for draining off unused electrons. They can't send them back to the power plant on the neutral - it would get congested, and the rate of flow would slow down. That's what causes brownouts.
The ground transmits the electrons back to the plant through conductive soil. |
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The ground is for draining off unused electrons. They can't send them back to the power plant on the neutral - it would get congested, and the rate of flow would slow down. That's what causes brownouts. The ground transmits the electrons back to the plant through conductive soil. It's what plants crave! 
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The ground is for draining off unused electrons. They can't send them back to the power plant on the neutral - it would get congested, and the rate of flow would slow down. That's what causes brownouts. The ground transmits the electrons back to the plant through conductive soil. Thanks for clearing that up.
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The ground is for draining off unused electrons. They can't send them back to the power plant on the neutral - it would get congested, and the rate of flow would slow down. That's what causes brownouts. The ground transmits the electrons back to the plant through conductive soil. ...and here we go... |
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...and here we go... Quoted:
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The ground is for draining off unused electrons. They can't send them back to the power plant on the neutral - it would get congested, and the rate of flow would slow down. That's what causes brownouts. The ground transmits the electrons back to the plant through conductive soil. ...and here we go... Lol, I think he was sarcastically referring to the leaky electron ground thread here a while back
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Lol, I think he was sarcastically referring to the leaky electron ground thread here a while back Quoted:
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The ground is for draining off unused electrons. They can't send them back to the power plant on the neutral - it would get congested, and the rate of flow would slow down. That's what causes brownouts. The ground transmits the electrons back to the plant through conductive soil. ...and here we go... Lol, I think he was sarcastically referring to the leaky electron ground thread here a while back I concur. I was in and out of that thread a few times. It got to tough/annoying trying to figure out who was serious and who was joking... |
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I concur. I was in and out of that thread a few times. It got to tough/annoying trying to figure out who was serious and who was joking... Quoted:
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The ground is for draining off unused electrons. They can't send them back to the power plant on the neutral - it would get congested, and the rate of flow would slow down. That's what causes brownouts. The ground transmits the electrons back to the plant through conductive soil. ...and here we go... Lol, I think he was sarcastically referring to the leaky electron ground thread here a while back I concur. I was in and out of that thread a few times. It got to tough/annoying trying to figure out who was serious and who was joking... It's was a hoot, though! |
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I concur. I was in and out of that thread a few times. It got to tough/annoying trying to figure out who was serious and who was joking... Quoted:
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The ground is for draining off unused electrons. They can't send them back to the power plant on the neutral - it would get congested, and the rate of flow would slow down. That's what causes brownouts. The ground transmits the electrons back to the plant through conductive soil. ...and here we go... Lol, I think he was sarcastically referring to the leaky electron ground thread here a while back I concur. I was in and out of that thread a few times. It got to tough/annoying trying to figure out who was serious and who was joking... People in that thread were joking? 
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The 'neutral is the grounded conductor.
It is used with the 'hot' conductor to operate electric equipment. The 'ground' is hte grounding conductor. It provides a fault path to trip breakers (or blow fuses) if the hot conductor contacts metal objects it should not. It is often referred to as the 'safety ground' since it provides a connection that has no current flowing and is tightly tied to zero volts and earth ground. The only time a grounding conductor carries ANY current is when something has gone wrong. The metal case of your tool has become energized. A metal junction box has become energized. It beats getting juiced. Ground Fault Circuit Interrupters (GFCI) provide an electronic method of detecting current in places it should not be. They then actually short the hot and neutral to trip whatever protection is on the circuit and turn it off. Arc faults detectors are triggered by the electrical 'noise' generated by a break that causes sparking (an arc) and open off the circuit. They also usually have a simpler GFCI function built in (it is not as sensitive to current as an actual GFCI device). |
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People in that thread were joking? Quoted:
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The ground is for draining off unused electrons. They can't send them back to the power plant on the neutral - it would get congested, and the rate of flow would slow down. That's what causes brownouts. The ground transmits the electrons back to the plant through conductive soil. ...and here we go... Lol, I think he was sarcastically referring to the leaky electron ground thread here a while back I concur. I was in and out of that thread a few times. It got to tough/annoying trying to figure out who was serious and who was joking... People in that thread were joking? Sadly, I think some of them weren't. |
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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, a10awg 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 Dan be a wire, bus had, 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 ICLD 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 sides to slap around in conduits or for bus bars to be physically attracted to each other (bent like a motherfucker) until they pissibly touch es higher 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. TL:DR OP doesn't understand electricity... |
| I might add that people who assume that the ground is there solely for safety rethink that position. Since the ground will carry fault currents back to the transformer, the ground can be and often is a deadly situation. The system ground in your house is there to provide an attractive path back to the source should a fault occur, such as a refrigerator housing becoming hot, etc. If the electrical system wasn't grounded, you'd be less likely to have a lethal episode if you were to somehow contact a leg of a phase. It would at least take the ground out of the equation to complete the circuit. |
The pic above is what your home's transformer would look like on an electrical print. You have the 7,200 volt primary voltage coming in and your 120/240 on the other side going out. The low side is what is known as a center tapped secondary. The center tap is tied to ground and forms your neutral connection and thus enables you to derive 120 volts from two different points with respect to it. Imagine that ground symbol on the center line (grounded neutral tap) as a boat anchor and the neutral as the ocean every one is floating on. If the boat anchor is raised above the bottom (earth), it will drift around. When it is on the bottom, it provides a solid anchor point. Your neighbors, the power company and everyone else are anchored to that same bottom, or reference point. That is your universal reference voltage. ETA and disclaimer....... (before anyone calls me out on it )
There are a few instances where the above is excluded. Some old delta systems are ungrounded. These are rare anymore and only found in old structures. For the most part, the above holds true! |
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http://i66.tinypic.com/2zebart.png The pic above is what your home's transformer would look like on an electrical print. You have the 7,200 volt primary voltage coming in and your 120/240 on the other side going out. The low side is what is known as a center tapped secondary. The center tap is tied to ground and forms your neutral connection and thus enables you to derive 120 volts from two different points with respect to it. Imagine that center line (tap) as a boat anchor and the neutral as the ocean every one is floating on. If the boat anchor is raised above the bottom, it will drift around. When it is on the bottom, it provides a solid anchor point. Your neighbors, the power company and everyone else are anchored to that same bottom, or reference point. That is your universal reference voltage. The utility doesn't use 7200v for their primary around these parts  ...
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The utility doesn't use 7200v for their primary around these parts ...Quoted:
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http://i66.tinypic.com/2zebart.png The pic above is what your home's transformer would look like on an electrical print. You have the 7,200 volt primary voltage coming in and your 120/240 on the other side going out. The low side is what is known as a center tapped secondary. The center tap is tied to ground and forms your neutral connection and thus enables you to derive 120 volts from two different points with respect to it. Imagine that center line (tap) as a boat anchor and the neutral as the ocean every one is floating on. If the boat anchor is raised above the bottom, it will drift around. When it is on the bottom, it provides a solid anchor point. Your neighbors, the power company and everyone else are anchored to that same bottom, or reference point. That is your universal reference voltage. The utility doesn't use 7200v for their primary around these parts ...Very standard around here. No matter, the principle is the same regardless of primary voltage 
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Quoted: The ground is for draining off unused electrons. They can't send them back to the power plant on the neutral - it would get congested, and the rate of flow would slow down. That's what causes brownouts. The ground transmits the electrons back to the plant through conductive soil. Outstanding!! You're hired.  |
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Outstanding!! You're hired.
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The ground is for draining off unused electrons. They can't send them back to the power plant on the neutral - it would get congested, and the rate of flow would slow down. That's what causes brownouts. The ground transmits the electrons back to the plant through conductive soil. Outstanding!! You're hired.
Senior engineer material there! 
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If you have neutral why do you need a ground? Because of some fancy-shmancy fizziks stuff, and some of that hippy safety crap. First, because wires do have some finite resistance, the neutral line at a receptacle will have a non-zero voltage, with the voltage depending on the amount of current running through it. Second, because believe it or not, people still sometimes get hot and neutral reversed. So, if you have an appliance with a metal chassis, and you want to protect the chassis so that a loose hot wire won't energize the chassis (and hence, whomever touches it), you tie the GROUND to it. If you tied neutral (as was done in days past), then sometimes backwards wiring meant 120V appliance chassis. Even if not, however, it could be several volts, leading to situations that are undesirable, one of which is that touching other appliances could combine circuit paths, potentially leading one neutral (which isn't usually through a breaker) to carry more current than it was rated for. Hot and neutral are there to make things work. Ground is there to keep you safe. |
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From one of my previous posts... Here is an old delta/delta system. No ground. We have some old buildings on the railroad that still have it. http://i63.tinypic.com/14269ue.jpg Wye? |
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Quoted: The ground is for draining off unused electrons. They can't send them back to the power plant on the neutral - it would get congested, and the rate of flow would slow down. That's what causes brownouts. The ground transmits the electrons back to the plant through conductive soil. I would hope that people are using dedicated grounds, so unscrupulous people don't redirect those loose electrons on their way back to the plant. |
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I would hope that people are using dedicated grounds, so unscrupulous people don't redirect those loose electrons on their way back to the plant. Quoted:
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The ground is for draining off unused electrons. They can't send them back to the power plant on the neutral - it would get congested, and the rate of flow would slow down. That's what causes brownouts. The ground transmits the electrons back to the plant through conductive soil. I would hope that people are using dedicated grounds, so unscrupulous people don't redirect those loose electrons on their way back to the plant. Those folks are dedicated all right
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The pic above is what your home's transformer would look like on an electrical print. You have the 7,200 volt primary voltage coming in and your 120/240 on the other side going out. The low side is what is known as a center tapped secondary. The center tap is tied to ground and forms your neutral connection and thus enables you to derive 120 volts from two different points with respect to it. Imagine that ground symbol on the center line (grounded neutral tap) as a boat anchor and the neutral as the ocean every one is floating on. If the boat anchor is raised above the bottom (earth), it will drift around. When it is on the bottom, it provides a solid anchor point. Your neighbors, the power company and everyone else are anchored to that same bottom, or reference point. That is your universal reference voltage. ETA and disclaimer....... (before anyone calls me out on it )
There are a few instances where the above is excluded. Some old delta systems are ungrounded. These are rare anymore and only found in old structures. For the most part, the above holds true! That's the current correct way of wiring but I have been told that there are old houses were line 1 is earth ground and others where line 2 is earth ground. Plus the ground is useful when things go wrong. 
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Very standard around here. No matter, the principle is the same regardless of primary voltage
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http://i66.tinypic.com/2zebart.png The pic above is what your home's transformer would look like on an electrical print. You have the 7,200 volt primary voltage coming in and your 120/240 on the other side going out. The low side is what is known as a center tapped secondary. The center tap is tied to ground and forms your neutral connection and thus enables you to derive 120 volts from two different points with respect to it. Imagine that center line (tap) as a boat anchor and the neutral as the ocean every one is floating on. If the boat anchor is raised above the bottom, it will drift around. When it is on the bottom, it provides a solid anchor point. Your neighbors, the power company and everyone else are anchored to that same bottom, or reference point. That is your universal reference voltage. The utility doesn't use 7200v for their primary around these parts ...Very standard around here. No matter, the principle is the same regardless of primary voltage
Preaching to the choir... |
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Well, technically, it is earth grounded
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The utility doesn't use 7200v for their primary around these parts ...Quoted:
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http://i66.tinypic.com/2zebart.png The pic above is what your home's transformer would look like on an electrical print. You have the 7,200 volt primary voltage coming in and your 120/240 on the other side going out. The low side is what is known as a center tapped secondary. The center tap is tied to ground and forms your neutral connection and thus enables you to derive 120 volts from two different points with respect to it. Imagine that center line (tap) as a boat anchor and the neutral as the ocean every one is floating on. If the boat anchor is raised above the bottom, it will drift around. When it is on the bottom, it provides a solid anchor point. Your neighbors, the power company and everyone else are anchored to that same bottom, or reference point. That is your universal reference voltage. The utility doesn't use 7200v for their primary around these parts ...Around here there is 7200 and 19.9kv. USED to have some old , really old 4kv but has all been upgraded in the last 30 years. Still some customer owned 4kv though. My transformer at my house is 19.9kv. |
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B-phase grounded systems have always escaped my understanding. Three phase system but only two pole breakers feeding three phase loads  Sure you're not thinking about single phase loads? (On a 3 phase system that would be any two phases) Delta systems can be really goofy. You can have ungrounded, corner grounded or high leg. There is also an open delta, where one phase is missing. |