Electrical for Dummies Part 2

[Kenneth Brown]

Ok guys heres a dumb question for ya. On a 120 circiut you have three wires. A black (HOT), a white (COMMON), and a green or bare (GROUND). I'm right so far correct? I have never understood why it is that a wire (ground) that is ultimately connected (at the box) to the same place as another (common) makes anything any safer. It just doesn't make since. Any takers?

 

[Pascal]

Re: Electrical for Dummies Part 2

The white wire (common or Neutral) is part of the circuit all the time. The ground connects the frame of the tool or appliance to the circuit back at the box so that if the wiring inside the tool contacts the frame, the power is more likely to pass through the wire than through the operator. The breaker will then trip when current flow reaches the setting of the breaker. <br /><br />In the north where block heaters are used, the ground wire is connected to the vehicle. If the heater element burns out and touches the engine block, someone touching the vehicle is more likely protected. <br /><br />People often replace the three prong cord end with a 2 prong or break off the 3rd prong to accomodate a 2 prong extension cord. Heater element burnout may energize the body. I've felt it a time or two myself. <br /><br />Appliances designed for indoor use use the polarized plug to ensure that the circuit is energized correctly. If the plug were flipped around, say on a toaster, it is possible that you would feel a "tingle" if you picked it up.<br /><br />Tools that use a polarized plug are usually double insulated.<br /><br />JD

 

[rwise]

Re: Electrical for Dummies Part 2

Further the "white" wire is intended to carry curent and the "green" or "bare" wire is not.

 

[flashback]

Re: Electrical for Dummies Part 2

I think you will find that in newer installs, the bare wire does not go back to the same buss as the white, but rather actually goes to a seperate buss which goes to a rod in the ground.......

 

[Pascal]

Re: Electrical for Dummies Part 2

The buss bar for the white wire is connected to the buss bar for the ground (bare) wire at the box

 

[Kenneth Brown]

Re: Electrical for Dummies Part 2

Thank you pascal, exactly what I am saying. If they are going back to the same place what is the purpose? It doesn't make since. I can se if they went to seperate locations but they don't.

 

[Pascal]

Re: Electrical for Dummies Part 2

The white wire and the ground wire are in parallel back to ground. <br /><br />The white wire is necessary to complete the circuit back to the power sub station and generation plant so the appliance will run.<br /><br />If there is a problem, the ground wire has less resistance than the human body (hopefully) and the current will take the path of least resistance. (prevents that tingle when you touch the metal case).<br /><br />If you bypass the ground wire, the only path left for the current to take is through the operator.<br /><br />In either case it will still take at least 15 amps to trip the breaker. <br /><br />I suppose you could connect the two wires to separate locations but that would mean that you have two ground rods and still really the same location just further down the circuit and more expense and hassle to install.<br /><br />In reality, the GFCI method of protecting the user is much more efficient. <br /><br />It monitors the difference in the current carried by the black wire compared to the current carried by the white wire. When the current in the white wire drops by about 5 milliamps from the black wire current the interupter trips in .025 seconds.

 

[crab bait]

Re: Electrical for Dummies Part 2

at the panel where the service first enters the house ( building ) i.e. main breaker an/or main breaker an multi-'circut' breakers is considered the main ... <br /><br />at the main,, the whites an ALL grounds go to the same busbar an MUST HAVE A BONDING SCREW installed to make the the busbar an the panel housing as one.. <br /><br />add ANY other panel after that is a sub-panel an the whites an the grounds are separate busbars the whites ( nuetral/commons ) on an insulated bus from the ground bus an NO BONDING SCREW required or wanted.. <br /><br />the real reason for this is i really don't know .. i should i guess but i don't.. <br /><br />all i know is ,is that it's CODE.. an it's how it's done an is important that it's done this way.. <br /><br />wait till monday.. i'll ask the general forman.. he taught 3rd year 'squids'...he'll know..

 

[BrianFD]

Re: Electrical for Dummies Part 2

The 'white' conductor returns the current to the neutral, the 'green' or 'bare' wire returns any current to the earth. Electricity always tries to return to its source, either via conductors or earth, whichever it sees as the path of least resistance. The fact that they are tied together at the panel box is of no consequence. Notice a transformer pole: The secondary neutral is attached to both the neutral conductor and to a pole ground which goes to the earth. This accomplishes two things: It tries to balance the difference in potential between the earth and the neutral, and it gives a better return path to the source.<br />Pascal did a good job of explaining the operation of GFI's (or GFCI's), what they monitor and how fast they operate. In each GFI outlet or breaker, there is a potential transformer that monitors current on the energized conductor and current on the return (neutral) conductor. If they don't match, the breaker trips, opening the circuit. For a better explanation, go here: GFCI's

 

[Kenneth Brown]

Re: Electrical for Dummies Part 2

GFCI's make since, its the other that doesn't. I guess I'll let yall in on a secret. I don't think you can convince me any different. I wire everything correctly but I don't understand why its the way it is. For me that is just as important to know as to actually doing it.<br /><br />Something I just thought of. Change the scenario slightly. I have 2 barrels of water. I have 2 siphon hoses. I can either put 1 in each barrel OR I can put both in one barrell and then both in the next. Either way the water is going to come from the same place, the same distance, the same routes, and get there at the same time. Both barrels will be empty using either method. What makes the ground/nuetral issue any different?

 

[Pascal]

Re: Electrical for Dummies Part 2

To make the the water barrel analogy fit the ground neutral situation, you would only have one barrel and two hoses. The hose that represents the neutral flows water all the time. The only time the other hose (ground) flows water is if the water is diverted some how. <br /><br />As with any analogy, this one has its limits too.<br /><br />You reference to the water barrel reminded me of a heated cattle waterer. If you don't have the ground hooked up correctly on the heater and the soil surrounding the waterer has the right moisture content, you have one of two situations: at least one dead animal or a lot of thirsty ones because they won't drink. They don't like the tingle either. <br /><br />The ground carries the problem current instead of the animal. There is no GFI on these applications as it would turn off the heater to easily and the water would freeze.

 

[crab bait]

Re: Electrical for Dummies Part 2

the ground an neutral is the same thing back at the transformer.. both get tried to XO on the transformer... the neutral is made by/in/thru the transformer secondary side .. <br /><br />the reason it become separate.. is because the neutral is a current carrying conductor..the return path from the load ..load is anything that is using the electric power.. lite bulb, motor, toaster, appliance,ect.. <br /><br />the ground is not a live wire.. <br />it's just a wire that travels along with the rest an gets bonded to every box, housing, metal, encloser, conduit, any metal object that the live wires pass/run thru or near, or by..<br /><br />a electrical circut is basicly a controlled short.. 2 wires connected together via a 'load'..<br /><br />TO, THRU, & RETURN is a circut..<br /><br />the power usage of the load keeps the circut from blowing...<br /><br />have a problem.. the stray current hops on the ground wire.. the ground wire is not connected to the load.. the circut blows because ya got a hot going an a ground wire ( now in the loop ) returning unabaded ( loadless) back to the panel to blow the breaker..<br /><br />that's why a GFI is so importain.. the ground wire ( three wire ) system is really only for equipment protection an not human protection.. <br /><br />the "unabaded ( loadless ) back to the panel to blow the breaker " is true but since your gettin' shocked ,, YOU BECOME THE LOAD.. an the breaker mite not ever trip .. being's you make a pretty good toaster.. ..

 

[rwise]

Re: Electrical for Dummies Part 2

Well, I have been "toasted" to many times!<br />Lets just say it's all about the $'s, the code is there and you have to pay $'s to have someone follow it! LOL

 

[TwoBallScrewBall]

Re: Electrical for Dummies Part 2

Right. I'll try to simplify it.<br /><br />Power is INTENDED to return to ground through the neutral wire. If for some reason the electrical component shorts out and load is shorted before it gets to the neutral wire, the ground wire is there to take the load back to the box instead of having it try to go back through your flesh. That's really all there is to it.

 

[Kenneth Brown]

Re: Electrical for Dummies Part 2

Crab bait says: have a problem.. the stray current hops on the ground wire.. the ground wire is not connected to the load.. the circut blows because ya got a hot going an a ground wire ( now in the loop ) returning unabaded ( loadless) back to the panel to blow the breaker..<br /><br />Steve says: Power is INTENDED to return to ground through the neutral wire. If for some reason the electrical component shorts out and load is shorted before it gets to the neutral wire, the ground wire is there to take the load back to the box instead of having it try to go back through your flesh. That's really all there is to it.<br /><br /><br />Guys, I will let you onto another secret. That makes since. I can see how it could help now. Thanks for edja-ma-cating this dummy.

 

[crab bait]

Re: Electrical for Dummies Part 2

i'll let you in on a secret, KENNY... you just stretched the limits of my intelligents.. don't do that anymore,,alright..!!

 

[Kenneth Brown]

Re: Electrical for Dummies Part 2

Mission accomplished crabby, if we don't work the brainit quits working period. I was always the one that never quit asking why. Most of the time it helped me and countless others understand things. Sometimes though it would put me in detention or with a letter sent home to the folks.

 

[dogsdad]

Re: Electrical for Dummies Part 2

Let me just throw this in because I skimmed over the posts and didn't see this mentioned: ground = 0 volts. In a properly wired scenario, any appliance you touch will be grounded. Your body is a parallel circuit to ground, but because of the fact the ground wiring is 0 ohms to ground, any stray voltage will push current to ground through the ground wire rather than your body. The appliance's chasis or body will never have voltage present. Theoretically.<br /><br /><br />-dd-

 

[crab bait]

Re: Electrical for Dummies Part 2

yeah, but don't let that theory bite ya-in-the-butt.. ..<br /><br />i know what you mean KENNY.. that's sage advice.. an it holds true for other 'units' ,also.. ..