Electrical question.........

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If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the panel, why are they both needed ????
Thanks Brian
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Brian wrote:

because the case ground is by definition not a current carrying conductor. I'm assuming you're referring to a dryer or range circuit in the US. There are some 120VAC components in each so the neutral is actually used. Useta be that you were allowed to use the ground as a neutral, but no longer. Think about it, that would be kind of like connecting the case of a metal tool like a hand drill to the neutral prong of the plug... sure, it should *theoretically* be safe, but it also increases the chances of something going wrong.
Now in the case of something like an A/C unit or a water heater, those are pure 240 so they don't need a neutral, just the two hots and a ground. If there *were* 120V components in those units you would then need to pull 10/3WG or similar.
nate
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Brian wrote:

On a 240V single phase circuit, a neutral is not needed. If you want to run 120V loads then you need a neutral, but then it's a 120/240V circuit.
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But doesn't 120 volt also use a neutral and ground ????
Brian
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Brian wrote:

120V circuits normally use a neutral. Grounds are used on both 120V and 240V circuits. The ground is a non current carrying safety connection, the neutral is the current carrying return path for the circuit.
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The fussier journeymen in our part of the country prefer to use one bus bar for grounds, the other for neutrals. Of course, the two busses are bonded together. Other than looking really spiffy, I don't know of any electrical advantage. Maybe one of our eminent electrical gurus can shed some light.
Joe
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Where there are more than one "ground bar" I use one for grounds & one for neutrals.......
why? I'm not sure except that's the way I was shown and I was told that grounds can be doubled up but neutrals cannot.
So by keeping them seperate it tends to enforce that behavior by treating them as "different". I guess that makes sense but in any case it works for me and the wiring looks neater.
cheers Bob
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The neutral and ground are run with two separate wires from the receptacle to the panel because if they were both on the same wire and that wire somehow opened between plug and panel, then the case of what ever was plugged in would become "hot"' if any current was flowing through the neutral. A real possibility f electrocution. Larry
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Brian wrote:

Hi, Neut. * L1 - @@@@@@@@@@@@*@@@@@@@@@@ - L2 * ground------* ///// Visually ground and neutral are physically tied together. Between LO1 and L2 is 240V, between L1 or L2 and neutral is 120V. Often this is called Edison circuit. G is for safety, N is part of circuit, current loop. You see some electrical devices has 3 prong plug and some has 2.
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As someone else pointed out, the ground is there for safety. It's not supposed to carry current, unless something goes wrong. For example, if a hot wire inside your refrigerator shorted to the metal cabinet. Without a ground, the case would become hot and you could be electrocuted. The neutral is there to carry the normal current. And if you had that connected to the metal case instead of the ground wire, if the neutral came open or developed a high resistance for any reason, all the metal case of the fridge and anything else on that line as well, would have energized cases.
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On Tue, 17 Feb 2009 06:21:14 -0800 (PST), snipped-for-privacy@optonline.net wrote:

But yet, you trader are going to point it out again. Why? As you always do. Wanting to reinvent the wheel just like all you boring EE's.

Oh, so its not supposed to carry current but it will? You sound like the weather man. "Today there will be a 50% chance of rain". That pretty much covers your ass.

Incorrect trader........as usual. You would only have a chance of being electrocuted if you made a path to ground. If your shoes are on you wont make much of a path to ground. And you call yourself and EE. What exactly does that stand for? (echo, echo because you like to hear yourself talk?

So anyways trader, this is payback for your jumping on my heart valve post. IF you would like to keep this shit up, have at it. I can have fun with you all day. Have a nice life Bubba
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Oh please, Bubba. If the case becomes hot, I said you COULD become eletrocuted, which is absolutely true. I don't have to list every condition that must be in place for that to occur.

After accusing me of giving being wrong, you state this whopper?
Bubba, go get your shoes on. Then go grab a hot wire in one hand and touch a water faucet or the metal range with the other. You can wind up dead with your shoes on. Also, only a fool would rely on shoes as being adequate insulation. How about if they are damp?

Bubba, you're the one here who keeps following folks around. First it was Ransley you were after, now it seems to be me. In the other thread, last couple days, you had a little war with Hank. Simple fact is, you can't seem to get along with anyone here. Seems more often than not, when you enter a thread, a flame war soon errupts. Gee, wonder why that is?
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On Tue, 17 Feb 2009 10:09:08 -0800 (PST), snipped-for-privacy@optonline.net wrote:

accurate? Bullshit. Making up your own rules as you go along again?

First off, dipshit, who walks around in their kitchen with wet shoes besides some cupcake like you? Second of all if I touch a cabinet of a refrigerator that happens to have a bad ground while standing in my shoes in the kitchen Im NOT going to be electrocuted you moron. Now, tell me how that statement is wrong again you dumb bonehead. EE's. What a pile of useless fuck heads. Thinking they have the correct answer to everything while not even knowing the basics of anything.

and as it appears, you do want to keep going so, "Game On!"

A war with Hank!? What, was it one or maybe 2 posts at the most there trader? Make up some more horse shit liar. Oh, and now you wish to be mother to everyone on the internet? You're a loser of a piss ant trader. Get a life. Is that your mommy calling you telling you to get off the computer now? Bubba
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I never said if you touch the cabinet of a refrigerator with just a bad ground you will get electrocuted. This is what I said:
"As someone else pointed out, the ground is there for safety. It's not supposed to carry current, unless something goes wrong. For example, if a hot wire inside your refrigerator shorted to the metal cabinet. Without a ground, the case would become hot and you could be electrocuted."
Everyone else understood that to be a true statement. This is an example of why you have such a hard time here in the newsgroup. You start a flame war over something that was either totally taken out of context or never said in the first place.

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On Tue, 17 Feb 2009 14:21:40 -0800 (PST), snipped-for-privacy@optonline.net wrote:

anything and everything completly different than the rest of the human race. That's what EE's tend to do. Deal with it. Its your problem. Bubba

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Bubba wrote:

Funny - whenever there is an argument it seems to be Bubba against the world. Must be your brain works funny. Or maybe you just don't understand the underlying science.
At least you provide humor for the day.
--
bud--

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wrote:

Bubba, A LOT of kitchens still have a metal edge on the countertop. Not many in the big city - but still a lot elsewhere. That metal edge CAN be grounded, and you CAN touch it and the fridge at the same time. THEN you DO get a dangerous shock. Or you have a ?grounded" item in your hand, and you bump the fridge. POW!!! It got ya. Or you are washing dishes, and the frige is, like in many kitsn 3 ft from the sink. You go to put a metal item in the dish drainer, next to the fridge. While you still have a hold of it with your wet hand it touches the fridge, (or some water has spilled over the drainer and the pan touches the water that has also touched the fridge. Nasty shock time.

Glad you're havin' fun Bubba.

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Brian wrote:

then both are hot.
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Brian
First things first. If it were in fact a 208,220,230,240 single phase circuit it would have only three conductors.
In that case each of the two conductors that are neither bare (uninsulated), green, or white would be the nominal phase voltage relative to ground. The third conductor is the Equipment Grounding Conductor (EGC). It might take the form of a bonded metal cable jacket, cable tray, or a metallic raceway, or a wire much like the other conductors of the circuit. If it is in the form of a wire it will be either bare (Uninsulated) or green in color or if it is American Wire Gage (AWG) size four or larger it would be color coded green at all accessible points. The reason that the third conductor can take the form of a metal enclosure around or supporting the energized conductors is that it only carries current during a fault condition. Provided that the EGC was properly sized and installed it will carry the fault current so well that the Over Current Protective Device (OCPD) that is protecting the faulted current carrying conductor will open and thus clear the fault.
If the circuit is a dual voltage circuit, such as 120/240 volt North American residential service range, clothes dryer, or feeder circuit then it will have both 120 volt and 240 volt loads supplied from the same circuit. In that case a forth conductor is run with the other current carrying conductors. That grounded current carrying conductor; which is commonly called the neutral; will be white in color or may be coded white at all accessible locations. Under most conditions of use it will be insulated and will not be supplied through an OCPD.
Up until quite recently it was permissible to bond the chassis of certain heavy appliances, such as stoves and clothes dryers, to the neutral conductor that served the loads in that appliance. Under some narrower circumstances the neutral conductor could be bare but never green. Since certain uses, found mostly in residences supplied with their own electrical service directly from the utility, the neutral could be bare some confusion has developed as to whether it was an EGC or a neutral. The code however was always clear that certain appliance chassis could be bonded to the neutral instead of having a separate EGC. The thinking was that these exception permitted circuits were never smaller then number ten AWG and were nearly always run from compression terminals to compression terminals so there was little risk of an open or high resistance connection. Likewise the feeder circuits were also run from and to compression terminals. Experience has shown that, although they are rare, high resistance and open conductors do occur in these circuits. Since the consequence of such circuit failures was the energizing of the chassis of large appliances or of the entire EGC system of separate buildings or feeder supplied panels at 120 volts relative to ground this practice has now been removed from the code and is only permissible in existing installations that predate the respective code changes.
What was wrong with this technique is that it violates a basic principle of safety engineering that holds that it should always take two or more failures in the system, at least one of which is easily recognizable as a condition that requires correction, to create an immediate hazard to life or health. With the four wire circuit any open in the neutral causes noticeable undesired operation such as the dryer not coming on or the stove's light and controls not working. Most importantly the undesired operation does not occur simultaneously with an immediate deadly hazard so that the users are unlikely to put up with the condition long enough for a complimentary fault to occur which would turn the situation hazardous.
I hope that is helpful -- Tom Horne
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Anyone who has ever stood barefooted on a concrete basement floor and touched the chassis of an old radio made during an era when it was common practice to ground the chassis to the neutral prong, knows well that the chassis is still hot relative to ground. Modern devices ground their chassis to the ground wire leaving no (or very little) electrical potential between a concrete floor and the chassis itself. If you touch a modern safety grounded device while standing barefooted on your basement floor you will not receive the jolt commonly received from old radios or TV's. There may be a few volts of potential there (see definition of a "ground loop") but not enough to feel or cause loss of life.
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