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Homeowner Forum / Repair / February 2006Ground Or Neutral Wire Question
Hello, Just want to get the terminology correct. Understand the differences between the Ground and the neutral in house wiring O.K., but for the bare wire that comes in from the street (along with the two phases) to the house service panel: is this correctly called a Ground wire or a Neutral wire ? Thanks, Bob > Hello, > [quoted text clipped - 9 lines] > Thanks, > Bob It is a grounded conductor commonly called the neutral. The wire that connects to your water pipe and ground rods is called a grounding conductor or more specifically a grounding electrode conductor. >>Hello, >> [quoted text clipped - 13 lines] > connects to your water pipe and ground rods is called a grounding conductor > or more specifically a grounding electrode conductor. FYI: May be no longer OK to ground to a water pipe in many locations now. I prefer to only use ground rods anyway. >FYI: May be no longer OK to ground to a water pipe in many locations >now. I prefer to only use ground rods anyway. Correction: if a building has metal water pipes, it is a Code requirement (and has been, for some time) that the metal water pipes be bonded to the building's grounding electrode system. The Code prohibits using metal water piping as the *only* grounding electrode.  SignatureRegards, Doug Miller (alphageek at milmac dot com) It's time to throw all their damned tea in the harbor again. >>FYI: May be no longer OK to ground to a water pipe in many locations >>now. I prefer to only use ground rods anyway. [quoted text clipped - 3 lines] >building's grounding electrode system. The Code prohibits using metal water >piping as the *only* grounding electrode. Which in clear but imprecise terms, means that the the piping has to be CONNECTED to the grounding system, but shouldn't be used as PART of it. You connect the pipes to ground, but you don't ground to the pipes. > >>FYI: May be no longer OK to ground to a water pipe in many locations > >>now. I prefer to only use ground rods anyway. [quoted text clipped - 8 lines] > used as PART of it. You connect the pipes to ground, but > you don't ground to the pipes. If the incoming underground water pipes are metal, one most certainly grounds the electric system "to the pipes". In fact NEC requires that underground metal water pipes (buried at least 20 ft.) be used as the primary grounding electrode when available. >> >>FYI: May be no longer OK to ground to a water pipe in many locations >> >>now. I prefer to only use ground rods anyway. [quoted text clipped - 13 lines] >underground metal water pipes (buried at least 20 ft.) be used as the >primary grounding electrode when available. Are you sure? I don't have a copy of NEC here, but what I remember was verbage more like this: "If ten feet of metal underground water pipe is available, it must be used as a grounding electrode; however, it must always be supplemented by an additional electrode." --- from: http://www.ventura.org/vcrma/build_safe/pdf/new_handouts_info/e-7.pdf Either way, the functional bottom line is that connecting the service-panel ground to the pipes is sometimes necessary, but never sufficient. I was under the impression that the purpose of that was to get electricity OFF the pipes, rather than to provide an additional path to ground. >>>>>FYI: May be no longer OK to ground to a water pipe in many locations >>>>>now. I prefer to only use ground rods anyway. [quoted text clipped - 32 lines] > purpose of that was to get electricity OFF the pipes, > rather than to provide an additional path to ground. I have no idea what "get electricity OFF the pipes" means. You are right about 10' - in the post of Rich256 the water pipe (plastic) is not a grounding electrode. Of the electrodes normally available in a house, the best by far is 10' or more of underground water pipe (doesn't have to buried 20') and if such pipe exists it MUST be part of the grounding electrode system. This was the only required grounding electrode until recently. The ONLY reason a suplementary electrode is necessary is that the metal water pipe may in the future be replaced by plastic (as Tom Horne said). Note the term "supplementary". If the water pipe is metal the supplementary electrode adds little or nothing. Of the "supplementary" electrodes that can be used, probably the worst is a ground rod because of high ground resistance. Unfortunately it is the easiest to provide. Far better. with a long term tested ground resistance of 5 ohms, is a concrete-encased electrode (Ufer ground). These are easy to include in new construction. Next best is probably a ground ring - also easy to provide in new construction. bud-- According to Bud-- <remove.BudNews@isp.com>: > Of the "supplementary" electrodes that can be used, probably the worst > is a ground rod because of high ground resistance. Unfortunately it is > the easiest to provide. Far better. with a long term tested ground > resistance of 5 ohms, is a concrete-encased electrode (Ufer ground). > These are easy to include in new construction. Next best is probably a > ground ring - also easy to provide in new construction. Recent electrical code revisions appear to be prefering grounding plates over rods. These plates are approx 12" square by 1/4" thick. More surface area than a rod. Somewhat trickier to install - undisturbed dirt contact, not just flung in the backfill. SignatureChris Lewis, Una confibula non set est It's not just anyone who gets a Starship Cruiser class named after them. > I have no idea what "get electricity OFF the pipes" means. I believe that this is the activity of making sure that the water coming out of your shower is the same electrically as your ground. That way, you do not get shocked just because you left hand is in the water while your right hand is holding the shaver with a case ground. AC mean that 30 time a second that one wire is +, the other 30 times a second it is -. Now, that timing needs to be the same as your water supply. That way, when your water is +, so is everything else. No current flow possible. If it is +, when everything else is -, then you get shocked. >> I have no idea what "get electricity OFF the pipes" means. > [quoted text clipped - 6 lines] > AC mean that 30 time a second that one wire is +, the other 30 times a > second it is -. No. 60 times a second one wire is + and 60 times a second that same wire is negative. The other is always at ground potential. The hot wire actually gets to about 170 volts positive and 170 volts negative during those swings. The RMS voltage being 120 volts. Or about 162 volts peak if we refer to it as 115 volts AC. A quick look shows there are quite a few web sites that describe this: http://www.ee.unb.ca/tervo/ee2791/vrms.htm Now if you have 240 volt service one of the hots gets 170 volts positive and at the same time the other line is 170 volts negative. They both cross the 0 volts at the same time. So if you are looking at them relative to each other the one line gets to be 340 volts different than the other. In Europe with 230 volt service one line is grounded and the other gets to 325 volts at 50 cycles (Hz). Or about 310 volts peak if you refer to it as 220 volts. >>>FYI: May be no longer OK to ground to a water pipe in many locations >>>now. I prefer to only use ground rods anyway. [quoted text clipped - 8 lines] > used as PART of it. You connect the pipes to ground, but > you don't ground to the pipes. Then what pray tell are you grounding to? The grounding impedance of two driven rods is often over fifty ohms. The grounding impedance of underground metal water pipes that are part of a community water system is usually less than ten ohms. Changing what we say does not reverse those figures. It is the underground metal water piping that provides the low impedance connection to earth. The driven rods are strictly a back up in case the piping is replaced with non conductive piping. -- Tom Horne Signature"This alternating current stuff is just a fad. It is much too dangerous for general use." Thomas Alva Edison > FYI: May be no longer OK to ground to a water pipe in many locations > now. I prefer to only use ground rods anyway. I have seen 3 ohms stated as a typical ground resistance for an urban metal water distribution system. The NEC considers 25 ohms ground resistance acceptable for a single ground rod, or you can use more than 2 rods and it doesn't matter. Would seem like a water pipe is a better grounding electrode. bud- Water line MUST be unified to electrical ground, and a jumper MUST be placed across the water meter so that ground is still good if the meter is removed and elmnates meter rubber washer interfying with a good connection > Water line MUST be unified to electrical ground, and a jumper MUST be > placed across the water meter so that ground is still good if the meter > is removed and elmnates meter rubber washer interfying with a good > connection And city code here requires electrical isolation from the water system. Meters, installed at the street, have about 10 feet of plastic pipe before they make connection with the copper pipes going to the house. >>> Hello, >>> [quoted text clipped - 18 lines] > FYI: May be no longer OK to ground to a water pipe in many locations > now. I prefer to only use ground rods anyway. In any installation governed by the US National Electric Code you must use the underground metallic water piping as a grounding electrode. Not using it is not a choice you would have. -- Tom Horne It is a neutral, which is grounded by the utility company on their end and grounded by the customer on their end > Hello, > [quoted text clipped - 9 lines] > Thanks, > Bob > Hello, > [quoted text clipped - 9 lines] > Thanks, > Bob It is a neutral and caries the difference in current back from the 2 hot legs. If you have a 100 amp service and one leg is at 60 amp and the other is at 40 amp then the neutral is 20 amps. If both legs are equal the current in the neutral cancels out to 0 amps etc. The 2 legs are not really 2 phases but rather 2 poles that are derived, by a center tapped transformer, from ONE the 3 phases that come from the power generation plant. The center tap being the neutral and grounded so it is at a 0V reference. Kevin According to Robert11 <rgsros@notme.com>: > Hello, > [quoted text clipped - 6 lines] > > is this correctly called a Ground wire or a Neutral wire ? Neither. John Grabowski's response is correct, but I thought I'd amplify. The technically correct term for the "neutral" in the house wiring, and the "non-hot" wire that comes from the street is "grounded conductor" - the conductor is groundED (at the panel). The technically correct term for the bare wire in house wiring is "grounding conductor" it provides the groundING for a circuit. Pedantically speaking, the term "neutral" can only be applied to the center conductor on a multi-phase circuit (eg: three phase). However, through common usage in the trade and elsewhere, "neutral" has come to be synonymous with "grounded conductor" and "ground"/"ground wire" synonymous for "grounding conductor". You'll occasionally see people use the "more-correct" terms here - usually confuses people. You'll impress the inspector if you use them ;-) SignatureChris Lewis, Una confibula non set est It's not just anyone who gets a Starship Cruiser class named after them. > According to Robert11 <rgsros@notme.com>: >> Hello, [quoted text clipped - 35 lines] > confuses > people. You'll impress the inspector if you use them ;-) The subject has been well covered but the term "neutral" was and is used by people in the electrical trade (electricians, linemen, engineers, writers, etc.) to refer to a grounded conductor, whether it is a center-tap or end connection. This usage basically means "not hot", or relatively safe. Don Young Black wire Neutral, Negative, -, Ground (This is the basically the negative end of the circuit) White wire Positive, Hot, + (This is basically the Positive end of the circuit, and is the one that comes from the breakers) No insulation or green insulation Ground, Case Ground (This is there to give the hot wire something easy to touch so that it will blow a breaker instead of laying there like a trap waiting for you to touch it, and is electrically the same as the Black Wire when you test it with your meter.) Be sure that all your plugs are wired the same or you can get shocked by touching two cases at the same time that are plugged into two different plugs. According to CanopyCo <Junk74020@aol.com>: > Black wire > Neutral, Negative, -, Ground > (This is the basically the negative end of the circuit) > White wire > Positive, Hot, + > (This is basically the Positive end of the circuit, and is the one that > comes from the breakers) You have your colour codes precisely backwards. Black is hot. White is neutral. In AC housewiring, "negative", "-", "positive" and "+" are simply wrong. It's AC, remember? SignatureChris Lewis, Una confibula non set est It's not just anyone who gets a Starship Cruiser class named after them. > According to CanopyCo <Junk74020@aol.com>: > > Black wire [quoted text clipped - 12 lines] > It's AC, remember? > -- Figures. Looks like I have them backwards. Anyone have a web cite that would show the correct wiring? I got my information form a web cite that had a picture of a plug. I still have the pic as a file to refer back to. No matter how you wire it, it has to be the same as what is already there. If they have it backward, then you better stick with there wiring code or you will get shocked. And as to + & - in AC, it is simply a better way to keep track of what is going on. You have to have a completed circuit to do anything (a + & -) and thinking of it this way helps keep things simple. Much to hard for most people to grasp that that one wire is a + 30 times a second, and a - 30 times a second. >> According to CanopyCo <Junk74020@aol.com>: >> > Black wire [quoted text clipped - 33 lines] > Much to hard for most people to grasp that that one wire is a + 30 > times a second, and a - 30 times a second. Actually it is + 60 times a second and - 60 times a second. Sixty hertz is "60 cycles per second" and each cycle has both + and - alternations. Reversed power wiring often is caused by people who are more familiar with automotive or electronic wiring than with AC power conventions. It obviously works but creates totally unnecessary and possibly severe hazards. Don Young >>> According to CanopyCo <Junk74020@aol.com>: >>> > Black wire [quoted text clipped - 38 lines] >Reversed power wiring often is caused by people who are more familiar with >automotive or electronic wiring probably negative-ground DC. where the - (ground) wire is often black. > than with AC power conventions. It obviously >works but creates totally unnecessary and possibly severe hazards. > >Don Young If you're using that 60Hz AC to power an incandescent light, the light output is 120Hz (since either polarity lights it). It wouldn't be easy to get 30Hz from it. SignatureMark Lloyd http://notstupid.laughingsquid.com "Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well armed lamb contesting the vote." - Benjamin Franklin > > Much to hard for most people to grasp that that one wire is a + 30 > > times a second, and a - 30 times a second. [quoted text clipped - 6 lines] > > Don Young You may be right. I would have to get access to an oscilloscope to be sure. Either way, it switched way to often and fast for me to try to keep track of it so I just try to make sure that all my plugs are the same. The thing that amazes me is how few people actually know or understand this fact (AC switches + & - on the same wire). I have even had people that worked with the electric company who's profession was to work on the high lines that constantly clamed that I was wrong. He kept saying that an AC current was traveling down the line, but could not comprehend what that actually meant. Swore that the + wire was always +, but with an AC signal going down it. >Black wire >Neutral, Negative, -, Ground [quoted text clipped - 4 lines] >(This is basically the Positive end of the circuit, and is the one that >comes from the breakers) Believe that at your own risk. Black is hot. Maybe you're getting it confused with DC (as in a car). >No insulation or green insulation >Ground, Case Ground [quoted text clipped - 6 lines] >by touching two cases at the same time that are plugged into two >different plugs. That is, black wire (hot) to the shorter slot and white wire (neutral) to the longer slot. SignatureMark Lloyd http://notstupid.laughingsquid.com "Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well armed lamb contesting the vote." - Benjamin Franklin >Black wire >Neutral, Negative, -, Ground [quoted text clipped - 4 lines] >(This is basically the Positive end of the circuit, and is the one that >comes from the breakers) Bzzzt! Sorry, but thanks for playing. That's exactly backwards. Hope you don't try to do your own AC wiring... SignatureRegards, Doug Miller (alphageek at milmac dot com) It's time to throw all their damned tea in the harbor again. > Hello, > [quoted text clipped - 9 lines] > Thanks, > Bob IMHO, it is a grounded [service] conductor. Notice the -ed suffix; it is important. I put service in brackets because you can usually leave that word out. Bob > Hello, > [quoted text clipped - 9 lines] > Thanks, > Bob It's confusing because a neutral wire is not required to be insulated when ran overhead. A true neutral carries the difference in current between TWO out of phase hot legs of a single phase system or TWO or more phases of a 3 phase system. The neutral also maintains a balanced voltage. That's why when there is a bad neutral connection in a house that some lights will be dim and others will be bright. In a house in a circuit that has a black, white, and bare wire in a romex cable, the white wire is technically _not_ a neutral wire since it does not carry the difference in current between two circuits. HOWEVER in the trade, to avoid confusion, any white or gray wire is called a "neutral", and any bare or green wire is called a "ground". The "ground", as electrician's would say, is technically the grounding conductor; more specifically, the equipment grounding conductor. If that isn't confusing enough we can throw in the term "bonding" :-) > Hello, > [quoted text clipped - 9 lines] > Thanks, > Bob There are hundreds of web sites that discuss this subject. For example: http://www.electrical-online.com/howtoarticles/Grounding.htm http://www.hammerzone.com/archives/elect/panel/breaker/install.htm > Hello, > [quoted text clipped - 9 lines] > Thanks, > Bob confusing you further is possible. The bare wire from the utility is a grounded conductor, not necessarily a neutral and has nothing to do with your house wiring terminology. The utility works on a different set of rules and regs. Where I live the bare conductor in the service drop is called the "messenger wire" or sometimes the 'static' wire. It is usually steel or steel core surrounded by AL. Much stronger than the "conductors" that are insulated. >>Hello, >> [quoted text clipped - 18 lines] > wire" or sometimes the 'static' wire. It is usually steel or steel core > surrounded by AL. Much stronger than the "conductors" that are insulated. Even though the neutral conductor on the entrance cable is grounded, that means is at ground potential but will carry current difference between the two hot legs. When suspended can be bare, others are insulated as so can be twisted together and not short. Buried lines have all conductors insulated. |
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