Site Notices
4/15/2014 2:52:24 PM
4/15/2014 11:16:20 AM
Author
Message
Merlin
Member
Offline
Posts:
Feedback: 100% (1)
Posted: 1/9/2003 7:22:09 PM

THE IMAGE ABOVE IS A PAID ADVERTISEMENT
I have some questions as to whether or not I have a good ground for the house wiring. Let me explain: I was recently underneath my house in the crawl space and found what I believe to be the 2 ground wires from my (1) 200 amp and (1) 100 amp service boxes in the garage. Neither wire was connected to anything! I took a length of #4 wire plus ground connectors and connected the 2 wires to my cold water copper pipes and to the #4 wire that I took outside and connected to the ground rod just outside. (The ground rod had one wire already on it, but I have no idea where the wire goes). I have seen installed several surge protectors that have a "ground" and "surge" light (Woods model 5185). Both lights are always on when installed in my house outlets. So, the question I have for my fellow AR15.comers is: How can I reliabily check the ground for my house wiring without resorting to the safe but perhaps costly measure of hiring an electrician. I'm fairly handy and typically do all my own wiring when adding house additions, wired my own pool etc. I've just always assumed that ground wire was good since its connected to a ground rod. Advice and comments welcome. Thanks, Merlin
colklink
Now with more than enough hair down there!
Offline
Posts:
Feedback: 100% (4)
Link To This Post
Posted: 1/9/2003 9:29:47 PM
I am not an electrician,I service different types of office equipment for a living and when I need to check to see if an outlet has a good ground I measure the voltage between the line and neutral(the 2 slits)should have 110 to 120,whatever your voltage is in your area.From the longer of the 2 slits to the round ground hole should also be 110.From the smaller slit to ground should be no more than 0.03 volts.If you have more you have a problem with your ground.If close to line voltage you have no ground.Hope this helps.














I don't get rich from stealing from the poor, you guys don't have any shit I want

-sirhacksalot


I look forward to the day when there will be less protests and more shooting

-
Skibane
Just 3 full magazines, and my swingin' cod...
Offline
Posts:
Feedback: 100% (3)
Link To This Post
Posted: 1/9/2003 9:49:27 PM
From the longer of the 2 slits to the round ground hole should also be 110.From the smaller slit to ground should be no more than 0.03 volts.
[b]Colklink[/b], you have it backwards! The small slot is the "hot" one — it should measure around 115 volts to ground. The large slot is neutral — it should measure no more than a couple of volts, depending on: 1. how far your outlet is located from the breaker box, and 2. how much current is being drawn from any other appliances, lights, etc. that are on the same circuit. Merlin, be careful when hooking up your ground rods. You could see some pretty high voltages on those "ground" wires if they ever lost all connection to ground. Best to disconnect power at your master breaker before handling them.
Hoppe's stinks.
ECS
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/9/2003 9:55:51 PM
I would not use your water pipes for a main electrical ground. You'd be better to drive a dedicated ground for the electical ground. Ground current flowing thru your water pipes can accelerate the corrosion process.
Blaster3094
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/9/2003 10:14:16 PM
The best way to check your house ground is to verify that you have current flowing in the wire to your ground rod. A clamp-on probe with a DVM (Digital Volt Meter) could be used to perform the measurement. Just make sure you have enough appliances running or lights lights on to generate a measureable ground current.
gomer
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/9/2003 10:14:32 PM
In many newer homes the ground and neutral wires are connected at the panel. DO NOT USE YOUR PIPES AS AN ELECTRICAL MEDIUM. There is the corrosion issue but also the possibility of electrocution. If you have a grounding rod in the ground and the wires are connected, you are grounded. If you want to check all your recepticles you can buy a little tester (inexpensive, no external probes) that has three light indicators. Plug it into the outlet and it will tell you whether polarity is correct, etc.
colklink
Now with more than enough hair down there!
Offline
Posts:
Feedback: 100% (4)
Link To This Post
Posted: 1/9/2003 10:24:28 PM
sorry about that,not something I have to do often.radio shack used to sell small device that just plugs into an outlet and tells you if you have a bad ground or not.














I don't get rich from stealing from the poor, you guys don't have any shit I want

-sirhacksalot


I look forward to the day when there will be less protests and more shooting

-
Merlin
Member
Offline
Posts:
Feedback: 100% (1)
Link To This Post
Posted: 1/9/2003 10:39:12 PM
Ok, I did some checking and one self help electrical type site I found the following from the NEC (National Electrical Code) 2000: "BONDING METAL WATER PIPES If you do not use the water pipes as the primary grounding electrode, because there is no metal water pipe in direct contact with the earth at least 10’ in length, NEC 250.52.A.1 and if your water pipes are metal, then you must bond your metal water pipes to the grounding electrode system. NEC 250.104.A This is required to make the water pipes one with the grounding electrode system the same as one entity. The purpose of bonding the metal water pipes to the grounding electrode system is so that if an energized wire comes in contact with those metal water pipes, a signal will go back to the panel that a short has occurred and the breaker serving or protecting that energized wire will trip due to a short circuit. This tripping of that breaker is due to the required interrupting rating of that breaker. NEC 230.208 You must bond the metal water pipes, and any other metal piping system, NEC 250.104.A including the gas piping NEC 250.104.B with the grounding electrode system of the structure. You must do this bonding of all metals of substantial quantities to make all metals one with the grounding electrode system serving that structure. The purpose of this bonding is to ensure that there is limited chance for a difference of potential between any metals in that structure, even the metal skin of a building. The intent is to make all metals one entity." So the above not only says I have to bond t metal water pipes, I should also ground the gas pipes also! Thanks for those who responded above. I'll get my multimeter and check the voltages for all three legs (L-N, L-G, N-G) and report the results here. Thanks, Merlin
CS223
I Am The Redneck Agenda!
Offline
Posts:
Feedback: 100% (40)
Link To This Post
Posted: 1/9/2003 10:53:55 PM
The proper way to test ground is with a device called a Megger. You measure between your home ground and commercial ground on the pole. IT should measure less than 0.1 ohm. Your power company should check this for you free of charge. Also, when wiring a ground, it should be in a star configuration, all your ground cables should come back to one point, like an "*" never use multiple ground rods, you can wind up with a ground potential difference which can cause havoc especially on electronic gear. Ideally, you should never be able to measure current through the ground cable, if you can you've got problems with your neutral connection, ground isn't the same thing as neutral, neutral is designed to carry more current. You can have a potential (voltage) difference between ground & neutral, it's not uncommon but usually only present when there is a significant current load. HTH
"Initially, always be courteous & polite, but have a plan to kill everyone that you meet" Bill Jeans, Morrigan Consulting
Skibane
Just 3 full magazines, and my swingin' cod...
Offline
Posts:
Feedback: 100% (3)
Link To This Post
Posted: 1/10/2003 12:37:38 AM
If you want to check all your recepticles you can buy a little tester (inexpensive, no external probes) that has three light indicators. Plug it into the outlet and it will tell you whether polarity is correct, etc.
The problem with most of these testers is that they use neon bulbs, which only light up if there's more than 60 or so volts present. Thus, you could still have a considerable voltage present on your ground or neutral wires without knowing it. [b]CS223[/b]'s suggestion to measure the resistance of the ground connection is a valid one, although IIRC, a "megger" actually measures resistances in the tens to hundreds of million ohms, and is used for testing the insulation in wires, appliances, etc. Not sure it would work for measuring resistances down to a fraction of an ohm. Also, note that using multiple ground rods is perfectly acceptable, as long as they are located within a few inches of each other and are all directly tied to each other. The idea is to get as good a connection with the earth as possible, without establishing several separate connections that are far enough away from each other to produce a difference in voltage between them. In this case, several inches doesn't qualify as "far enough" away to cause any problems. In some areas, the soil is simply too poor a conductor to obtain an adequate ground with just one rod. Bonding to pipes may improve the connection somewhat, as does "salting" the soil around the ground rod with rock salt. Using multiple ground rods is another viable option, observing the above precautions.
Hoppe's stinks.
sniper1az
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/10/2003 12:49:15 AM
Just make sure that you get a "real" ground rod. At least 6' in length and MUST be copper clad. If you arn't sure what is underground, call Bluestake & have them mark your utilities prior to driving that bad boy in !
DzlBenz
Not available in stores.
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/10/2003 12:55:33 AM
My Dad (RIP) was a Union Electrician for 25 years. Here's what he taught me about electricity: If you can see it, it's bad.
ONLY PEOPLE WHO LACK A CERTAIN AMOUNT OF CONFIDENCE AND CAN'T COME UP WITH A DECENT ARGUMENT TYPE IN ALL CAPS.
MickeyMouse
Offline
Posts:
Feedback: 100% (10)
Link To This Post
Posted: 1/10/2003 1:07:29 AM
Some years ago I worked for the power company. Checking ground rods is time consuming and not alway enlightening. I hated it. Drive several and bond them all together with #4 solid. The more the merrier. As far apart as you can get them. If you live in the country, bond to your steel well casing. Place a rod near your leach bed. In the city, often the water line from the meter to the house is K copper and an EXCELLENT ground. All depends on how serious you want to get and what problem you wish to solve. With normal soil types and no on going lightning issues, drive one 10' copper clad rod and be done with it. Your existing ground wire MAY go to the meter socket. Some jurisdictions do it that way. Works, but bonding the boxes too is an even better move. I remember a substation we had in hilly, rocky country. Could NOT get a decent ground. Must have had a hundred rods in the ground (about 2 feet because of the stone) plus a "copper mesh matt" under the yard. Didn't work. Not even a little. Drilled a half dozen water wells, lowered 2" copper pipe (schedule 80!!) into the wells and bonded to those. Still that way. Worked - WE had a good ground. Trouble is, the phone company DIDN'T. Every time a storm moved through, anything tied to the phone line just disappeared!! Nothing but a charred stripe on the wall where the wire WAS. Have had to pry more than one phone off the steel desk with a crow bar. Any radio gear we had tied to the TELCO lines became an empty burned box after a storm. Used all kinds of arrestors to reduce the problem but that in another story.....
Diplomacy is the art of saying "nice doggie" while you're looking for a rock." Will Rogers
sr15
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/10/2003 1:40:49 AM
Wow, there is some interesting information floating around this thread. First of all, most states have adopted the 2002 National Electric Code or an amended, more strict, version of the NEC as part of their building code. The 2002 NEC REQUIRES that if you have a metal water pipe in contact with earth for more than 10 feet, it shall be used as your grounding electrode and no ground rod is needed. Current should not normally flow in the gounding electrode, so the corrosion problems are a myth. If you have metal water pipes in you house, but a non-metal service from the water meter, then the metal pipes must still be bonded to the grounding electrode system. In this case, the grounding electrode would most likely be a ground rod, but other methods are permitted. And actaully, if the resistance between the earth and the ground rod is greater than 25 ohms, an additional ground rod should be installed. Metal gas pipes must also be bonded to the grounding electrode system. This is so that all metal systems in your house are always at the same potential (earth), which minimizes the possibility of getting shocked. The easiest way to check your receptacles for proper wiring is to buy one of those $10 testers mentioned above. It will tell you if each of your receptacles are wired properly, but not if the ground terminal is actually connected to the ground rod. So, if you check the receptacle and they are wired properly, and you still want to know if the ground terminal is bonded the ground rod, then do this. Get a Ohm meter and a long piece of wire. Connect one end of the wire to your ground rod and the other end to one of the ohmmeter leads. At each of your pannels, check for continuity by placing the other ohmmeter lead on the ground bus. You should read less than about 5 ohms. If so, then your ground terminal is properly connected to the grounding electrode. You can also check the continuity of anything else that's supposed to be grounded (gas pipes, stove, refrigerator, etc.). You should never see more than about 5 ohms. hope this helps
sr15
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/10/2003 1:57:09 AM
Oh yeah, Merlin, check your IM
Merlin
Member
Offline
Posts:
Feedback: 100% (1)
Link To This Post
Posted: 1/10/2003 8:04:31 AM
From above: never use multiple ground rods, you can wind up with a ground potential difference which can cause havoc especially on electronic gear. I think I found one possible problem: The swimming pool breaker box near the pump pool also has a ground rod that has a #6 wire attached to it. The wire is connected to all the metal near the swimming pool AND it is connected to the ground bar inside the breaker box. This breaker box is connected to the main service panel with 8/3 wire UF wire bundle (cable that can be directly buried since it goes through the crawl space is partially located outside under the rear deck and has 3 insulated wire (H-H-N) and a bare ground wire). The ground wire back to the main service panel is connected to the breaker box ground bar. This means I have to grounds separated by about 75 feet or so and connected with #8 wire. Could this be the source of the problem? Thanks for the help in checking my ground system! SR15, what's IM? I usually can't post my e-mail address since its a work address. Thanks, Merlin
David_Hineline
Team Member
Offline
Posts:
Feedback: 100% (12)
Link To This Post
Posted: 1/10/2003 8:28:35 AM
Blaster3094 Very bad advice. The only purpose for the third wire ground stud is a safety circuit. If you have current flowing through the safety ground to your ground rod then something in your wiring is leaking current and is an unsafe condition.
Class Three Shooters Blow Thier Loads with just One Pull of the Trigger.
tnek
Member
Offline
Posts:
Feedback: 100% (6)
Link To This Post
Posted: 1/10/2003 8:44:40 AM
Im Industrial not residential/construction but I think MickeyMouse has it best. The emphasis on bonding multiple grounds is on the money. Now do we start talking about Chasis ground vs. Ground to Earth?
MickeyMouse
Offline
Posts:
Feedback: 100% (10)
Link To This Post
Posted: 1/10/2003 9:10:25 AM
"Ground" in electronics can be a subject unto itself!! Ground loops, ground currents, isolated grounds etc. can be nightmarish. Another interesting utility story. Most power poles have a ground wire. Just a length of #6 solid stapled to the butt before it is set in the hole. These are deep (10% + 2') so make a good ground most of the time. The #6 is tied to the neutral up on the pole. The locals were stealing primary wire for the copper. Smarter than some, as they were stealing the neutral not the "hot" line (7620 volts!!). Noticed the ground wire at a certain pole was surrounded by a couple feet of really dead grass. Further examination revealed a dead rat. Hummmmm. Got to checking and found a number of spans of missing neutral up the road. When the crew fixed it they told me there was some 75 amps on the line - all that had been going to earth since the two legged rats had stolen the wire. Voltage gradient at the pole ground had been high enough to kill the other rat and baked the soil to powder (I looked AFTER they fixed the line!). Had a man touched that pole, he most likely would have went the way of the rat (mousy kind, not the thief). Large currents tend to ruin a driven ground, at least for a while. Time at current will slowly heat and evaporate the water which increases the resistance creating more heat and faster evaporation. Points learned: Grounds are good, they can save your life - or take it. Grounds do fail even if once good. Keep your hands off poles. If you have ground current - any - find out why and deal with it! Be observant. A home driven ground can really save you a bunch of money not to mention your life. It really helps with lightening. At least as important is what happens if the neutral of your incoming service is lost? If you have a good driven ground, not a lot. However, without it you can expect to see all the light bulbs and appliances connected to ONE leg (115 volt) destroyed!
Diplomacy is the art of saying "nice doggie" while you're looking for a rock." Will Rogers
CAMPYBOB
Offline
Posts:
Feedback: 100% (1)
Link To This Post
Posted: 1/10/2003 9:40:32 AM
5/8" x 8' copper clad steel ground rods are sold at home depot and lowes. i installed 3 of them (10' spacing) on the electric fence (lightning protection).
sr15
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/10/2003 3:36:59 PM
[Last Edit: 1/10/2003 3:46:44 PM by sr15]
Originally Posted By Merlin: From above: never use multiple ground rods, you can wind up with a ground potential difference which can cause havoc especially on electronic gear.
Sorry, but this is just plain wrong. There are many times when you are actually required to install two or more ground rods for one service. It will not affect electronics at all except during a lightning strike and then you want as many ground rods a possible.
I think I found one possible problem: The swimming pool breaker box near the pump pool also has a ground rod that has a #6 wire attached to it. The wire is connected to all the metal near the swimming pool AND it is connected to the ground bar inside the breaker box. This breaker box is connected to the main service panel with 8/3 wire UF wire bundle (cable that can be directly buried since it goes through the crawl space is partially located outside under the rear deck and has 3 insulated wire (H-H-N) and a bare ground wire). The ground wire back to the main service panel is connected to the breaker box ground bar. This means I have to grounds separated by about 75 feet or so and connected with #8 wire.
Merlin, this is an acceptable installation. You are required by code to provide an additional ground rod at that location and it must be bonded to the ground rod at your service entrance. It is acceptable to use the grounded conductor (neutral) for this connection.
Could this be the source of the problem?
No, that should not affect your receptacles. Buy one of those testers first and check to see if your receptacles are wired properly.
sr15
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/10/2003 4:14:52 PM
Originally Posted By Merlin: I have seen installed several surge protectors that have a "ground" and "surge" light (Woods model 5185). Both lights are always on when installed in my house outlets.
Are you sure that these lights are supposed to be off? Several of my surge protectors have "ground" lights that are illuminated when a proper ground is present. And on one of them, an illuminated surge light indicates that it's protected, but on others an illuminated surge light means it's had a surge. If that surge protector is a fairly cheap model (less than about $40), then it probably only uses MOV's (metal oxide varistors) for the protection. MOV's have a finite life and can not withstand multiple overvoltages. So, it may have seen a surge and now it's time to get a new one. I've had to replace several of mine. I finally quit buying surge protectors that only rely on MOV's after I lost a computer duing a lightning strike.
Merlin
Member
Offline
Posts:
Feedback: 100% (1)
Link To This Post
Posted: 1/12/2003 11:41:36 AM
[Last Edit: 1/12/2003 11:43:00 AM by Merlin]
OK, thanks for all the comments and help. I've confirmed via e-mail with Woods that both the ground and surge light are supposed to be on. They said if either ever turned off, then I have a problem. SR, yea,I know about MOV's they suck for longevity. But, since I cannot find any useful info on a better surge protector and how they protec (i.e. which technology they use), I refuse to spend anymore $. Besides, it will be pretty cheap to replace in a few years. SR, also, I've lost the bubble: which testor are you recommending? Thanks guys! Merlin
sr15
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/12/2003 2:06:23 PM
[Last Edit: 1/12/2003 2:20:43 PM by sr15]
Originally Posted By Merlin: SR, yea,I know about MOV's they suck for longevity. But, since I cannot find any useful info on a better surge protector and how they protec (i.e. which technology they use), I refuse to spend anymore $. Besides, it will be pretty cheap to replace in a few years.
I'm using a UPS and a [url=http://catalog.belkin.com/IWCatProductPage.process?Merchant_Id=&Section_Id=71&pcount=&Product_Id=100991&Section.Section_Path=%2FRoot%2FPowerProtection%2FComputer%2E%2E%2Eotection%2F]Belkin Surge Protector.[/url] These surge protectors use high frequency inductors and film capacitors in addition to MOV's and TVS's. They have an unlimited equipment waranty and data recovery waranty. Well worth the extra money, IMO.
SR, also, I've lost the bubble: which testor are you recommending?
[url]http://doityourself.com/store/6747471.htm[/url] If you get one of those testers, check your GFCI receptacles/breakers as well. GFCI devices have a history of failing during voltage disturbances. The receptacles will still work, but the GFCI circuit won't. You won't know it unless you either get shocked or test it.
levi
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/12/2003 4:01:25 PM
I read your post when you first put it up but didn't respond. Electrical work is best left to licensed qualified individuals if you don't understand it or feel uncomfortable with it, but I will give you my view now after reading some of the comments that have been posted since. The electrical code is there for a reason and it makes sense but leaves a lot to be desired when a non electrician reads it and tries to interprete it word for word. But then again it wasn't written for them. Reading the previous posts, one says not to use multiple ground rods and another says to use as many ground rods as needed to get a good ground. Another says use the star configuration. I agree with all these answers and believe they are correct even though on the surface they might seem contradictory or confusing. The reason I say these are correct is, first you drive as many ground rods as necessary to get a good ground while wiring them all together. This group of rods becomes a single rod (electrically speaking) if you tie the electrical wire to this group of rods at one point and one point only (remember this). This one point will also follow the rule of the star configuration connection. If at any point you run two separate electrical ground wires, one going to one rod at one point and another electrial wire going to another rod at a different point, it all falls apart. Then you get ground potential problems also know as ground loops. The code also talks about bonding metal to wire. I won't disagree with the code either but I have never felt totally confortable about this. This is apart from the subject of galvanic corrosion of dissimilar metals. On newer houses, in the Southwest at least, all piping underground is most likely PVC with the exception of natural gas. All water piping above ground is usually copper. The fact that no copper is buried at any point means this plumbing system is already isolated from the electrical system. Why then tie it back in to the electrical system? I would have to weigh the possiblity of the plumbing system to ever recieve a direct short that case ground wires or GFI wouldn't take care of first. Proper use of green case ground wires along with proper use of Ground Fault Interrupts should take care of any safety concerns. I'll get to my main point by relating an electrical problem I fixed involving the ground rod, buried piping and bonding metal to wires. A family (friends) I know of are lucky they didn't get electrocuted. They had an electrical problem. When they would take a shower they would turn on the water, set the temp, and jump in. Once they were soaking wet they would get zapped, enough to definitely get there attention if they were to touch the shower handles when adjusting the temp or to turn it off when they were done. It took me a while to track down the problem. You have to understand that this was an older house still wired according to code as far as I could tell. I say this because I don't claim to know the code 100% and I am not an electrician either but everything I saw was to code. The problem turned out to be a combination of things. The ground rod single point connection was loose somewhat and showed signs of oxidation yet all appliances still worked but lights would dim on load surges. An old evaporative cooler with frayed wet wiring didn't help(scary). A old metal cased multiple outlet connector had a bad filter/bypass capacitor that was starting to break down and leak through. You would get a tingle here just by touching the case even though this problem was probably separate for the main issue. In any case taking care of these corrected the problem(15 years ago). If I were to pick the main cause of the problem, it would have to be the evaporative cooler. Lucky for them the buried piping drew much of the current along with the ground rod, but the electrical system still had enough resistance/impedance left to cause a difference in ground potential resulting in lightly zapped them when in the shower. You could say that the buried pipes (galvanized) and metal bonding helped keep this family from getting electrocuted, but at the same time contributing to the ground loop potential problem mentioned. If you treat the buried pipe as a second ground rod with multiple connecting points, if fails the star configuration from the word go. So which is correct? Everything is still to code as far as I can tell. I realize none of the above really serves to answer your question, but is food for thought. So, to answer your question, I would tie the two wires together and run them to the ground rod and tie it next to the single wire you menttioned that was already there. Then I would run a totally separate wire from the pipe to the ground rod and tie it next to the other two. These three connections can be consider a single point being they are that close to each other. I would say your ground rod and ground system overall is OK if all your appliances are working and can handle power surges when you turn on your appliances or the central A/C. Ditto on that three prong electrical plug wiring tester. It works. Get one. Be safe.
MickeyMouse
Offline
Posts:
Feedback: 100% (10)
Link To This Post
Posted: 1/12/2003 6:49:47 PM
Multiple ground rods tied together is fine. They should be connected to entrance box ground as per local jurisdiction. Multiple grounds, such as driven rod AND buried water pipe is OK too. "Ground loops" in this situatinon is not much of an issue. If water pipe to house is plastic, the water lines IN house, if metal, should STILL be bonded as per NEC. If done, this prevents the "tickle in the shower". FAiled electric water heater elements are particularly dangerous should the tank "green ground" fail. Gas piping must be bonded as well, per code. Natural gas meters have a dielectric union at the meter that isolates the house piping from the service piping coming from the utility. Need to keep that house pipe from becoming energized! Electronic ignition furnaces DEMAND a good ground on the gas piping to work. Power surges from things turning on or off should NOT result in dimming of lights, lights getting brighter or ANY safety ground current. If you have any safety ground current at any time, (other than lightning) find the cause and FIX IT. Don't be misled by all the hype surrounding surge protectors!! Some help a little. NONE are a cure all. They will NEVER reduce your bill nor will they protect equipment ALL the time! Believe about 5% of what you read, if that. Truly good ones are NOT cheap. Whole house lightning arrestors (GE makes a good one) are worth the cost too.
Diplomacy is the art of saying "nice doggie" while you're looking for a rock." Will Rogers
sr15
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/12/2003 7:25:50 PM
[Last Edit: 1/12/2003 7:42:36 PM by sr15]
Originally Posted By levi: The code also talks about bonding metal to wire.
Yes it does. Section 250.104 A,B, and C Bonding of Piping and Piping Systems and Exposed Structural Steel. ...metal water piping shall be bonded... ...metal piping systems, including gas piping, that may become energized shall be bonded... ...exposed structural steel that is interconnected to form a steel building frame and is not intentionally grounded and may become energized shall be bonded...
I won't disagree with the code either but I have never felt totally comfortable about this. This is apart from the subject of galvanic corrosion of dissimilar metals. On newer houses, in the Southwest at least, all piping underground is most likely PVC with the exception of natural gas. All water piping above ground is usually copper. The fact that no copper is buried at any point means this plumbing system is already isolated from the electrical system. Why then tie it back in to the electrical system? I would have to weigh the possibility of the plumbing system to ever receive a direct short that case ground wires or GFI wouldn't take care of first. Proper use of green case ground wires along with proper use of Ground Fault Interrupts should take care of any safety concerns.
Ok, suppose I'm in a house with copper pipes, the water service from the meter is non-metal (pex, quest), and the copper piping system is not bonded. Now suppose somehow an ungrounded ("hot") wire comes in contact with the piping at some point. There are many way this can happen. A problem at the water heater, clothes washer, dishwasher, or inside the walls. The moment the wire contacts the copper pipe, the entire piping system rises to a potential of 120 Vac. But, no current flows since there is not path to ground, so the breaker would not trip. Now the first person to come in contact with the piping system (grab a faucet, etc.) will be shocked, since he will be the path to ground. If the wire that faulted was a major appliance circuit or a lighting branch circuit, odd's are it would not be GFCI protected either.
...If I were to pick the main cause of the problem, it would have to be the evaporative cooler. Lucky for them the buried piping drew much of the current along with the ground rod, but the electrical system still had enough resistance/impedance left to cause a difference in ground potential resulting in lightly zapped them when in the shower. You could say that the buried pipes (galvanized) and metal bonding helped keep this family from getting electrocuted, but at the same time contributing to the ground loop potential problem mentioned. If you treat the buried pipe as a second ground rod with multiple connecting points, if fails the star configuration from the word go. So which is correct? Everything is still to code as far as I can tell.
The code does not require that the grounding electrode system be in a star configuration, but it does require all of the following to be bonded, if present, to form the grounding electrode system: underground metal water pipe in direct contact with the earth for more than 10ft., metal frame of the building or structure, concrete-encased electrode, ground ring, rod and pipe electrodes, plate electrodes, and other local metal underground systems or structures. Section 250.52 A1,2,3,4,5,6,7. My guess is a "hot" wire from the evaporator came in contact with a metal pipe somewhere. If the metal pipe was isolated from earth, then you would have had the scenario I just mentioned above. However, since it was in contact with the earth, you're right additional current was flowing through ground also. But the path to ground apparently had too much impedance to trip the breaker/fuse. If the grounding electrode conductor was securely fastened to the ground rod, and the metal piping was properly bonded, then the instant the wire from the evaporator came in contact with the pipe, the breaker would have tripped. And then you would have known there was a problem immediately. That's the point of having all "substantial" metal systems bonded together and capable of delivering fault current to ground. As soon as a wire faults, the breaker opens and no one gets shocked. Hope this clears things up a bit. By the way, yes, I'm a licensed electrical contractor. I'm also about 4 months away from finishing my third Electrical Engineering degree (a Ph.D.).
Merlin
Member
Offline
Posts:
Feedback: 100% (1)
Link To This Post
Posted: 1/13/2003 9:15:31 PM
SR, Thanks for the help!!! Merlin
sr15
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/13/2003 11:40:27 PM
Originally Posted By Merlin: SR, Thanks for the help!!! Merlin
You're welcome. Glad I could help.
Blaster3094
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/14/2003 12:42:15 AM
[Last Edit: 1/14/2003 12:42:59 AM by Blaster3094]
Originally Posted By David_Hineline: Blaster3094 Very bad advice. The only purpose for the third wire ground stud is a safety circuit. If you have current flowing through the safety ground to your ground rod then something in your wiring is leaking current and is an unsafe condition.
I beg to differ with your statement as it refers to my comment. Yes current in the safety ground is BAD. That means you have lost your neutral, therefore the Safety Ground is performing its function. Now if you examine my original post I was referring to the HOUSE Ground and verifying it's integrity. There will be and should be current flowing on the House ground. The House ground is a completely different animal than the Third Wire Ground (AKA, Safety Ground). The Electric Utility drops provide two wires for typical residential service each 110 VAC RMS with a potential across both of 220 VAC RMS. The Utility does not provide a Neutral or a Ground; this is where your House Ground comes into the equation. In order to establish a circuit there must be a return path and since the Utility is referenced to ground your House Ground completes the circuit.
sr15
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/14/2003 1:44:51 AM
Originally Posted By Blaster3094:
Originally Posted By David_Hineline: Blaster3094 Very bad advice. The only purpose for the third wire ground stud is a safety circuit. If you have current flowing through the safety ground to your ground rod then something in your wiring is leaking current and is an unsafe condition.
I beg to differ with your statement as it refers to my comment. Yes current in the safety ground is BAD. That means you have lost your neutral, therefore the Safety Ground is performing its function. Now if you examine my original post I was referring to the HOUSE Ground and verifying it's integrity. There will be and should be current flowing on the House ground. The House ground is a completely different animal than the Third Wire Ground (AKA, Safety Ground). The Electric Utility drops provide two wires for typical residential service each 110 VAC RMS with a potential across both of 220 VAC RMS. The Utility does not provide a Neutral or a Ground; this is where your House Ground comes into the equation. In order to establish a circuit there must be a return path and since the Utility is referenced to ground your House Ground completes the circuit.
Actually, David is right. The utility does in fact supply a neutral. Just look at any residential overhead service drop. There are three conductors (triplex), two insulated AL conductors and one non-insulated ACSR conductor. The non-insulated conductor is the neutral and is connected to the centertap of the transformer and the neutral terminal at the meterbase. It should be grounded at the transformer and at the meterbase. Very very little current should be flowing through the grounding electrode conductor (the conductor connected to the ground rod). Nearly all of the current should flow through the neutral conductor, NOT through ground.
Merlin
Member
Offline
Posts:
Feedback: 100% (1)
Link To This Post
Posted: 1/14/2003 7:28:51 AM
I looked at both of my main panels last night, and there are definitely a neutral wire from the meter/power company in each panel. I've decided to add 2 more ground rods in front of the house. One will be right in front of the small crawl space vent where my current ground wire goes and one to the right of it. This will make a total of 3 ground rods, with the 2 new ones further from the house and beyond the drip line. I will also extend both panel ground wires to tie directly into the main/middle rod (right now they are spliced together and have a 20 foot lead. Before I do anything, the first thing I will do is to see if I can get an accurate reading on the current resistance between my panel ground bars and the current ground rod. I'll then compare that figure with the new configuration. Thanks again for the help. Merlin
Blaster3094
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/14/2003 10:57:54 AM
Guys, Sorry for the bogus information. The medicine I have been on and the flu I have must have clouded my mind. I spent time years ago working with 3-phase equipment that did not use a neutral, thats the only thing I can think of that made me say that the Utility does not provide a neutral. Of course they do. Now as far as the House Ground goes, someone once told me that you could measure ground current. Perhaps, and I am only guessing here now, what they were talking about is leakage current. In other words part of the current that would be flowing out of your house on the neutral would choose the path of House Ground. Both the neutral and ground bus in your breaker box are at equal potential aren't they? So if you have a good earth ground for your house perhaps some current would follow that path?
Merlin
Member
Offline
Posts:
Feedback: 100% (1)
Link To This Post
Posted: 1/14/2003 12:52:20 PM
Blaster, The only way that current could flow is if there is a voltage potential, which, theoretically, there shouldn't be. Now that you mention it, I should think of a way to measure any current in the existing ground system. Hmmmm, more food for thought. Thanks, Merlin
Guncrazy223
Black sheep of NEO
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/14/2003 1:45:47 PM
I beg to differ with the idea that MOv's are not a good way to provide surge protection. I worked for a place that designed and built MOV's for power lines. We also built MOV's for things like MRI machines. A GOOD MOV, can withstand multiple strikes and can last a very long time. How often do you think a power company want's to be replacing these things. MOV's biggest problem is heat from a lot of time overvoltage unlike normal resistors that have an increase in resistance with heat, MOV's are the opposite so if they get hot they conduct better and at some point they will burn up. It's cool how powerful an MOV can explode when hit with 10,000 amps multiple times. I helped design an arrester while I worked there so I did some research into this and I didn't find another way that was economically feasable as surge protection. Though some people like sparkgaps in conjunction with MOV's. Back to the original question. Where I live multiple ground rods are a requirement. They want them near a downspout so they get alot of water when it rains. If your worried about ground just put in some ground rods yourself, and run the proper wire for your service back into the box. It is very easy just dont touch the wires coming in from the street. Those can sting a little. Those little plug in testers are nice to make sure everything is wired right but they don't tell ya squat about a good ground. A 30 ga wire to ground will make one of those light up. It basically just tests for voltage from L-G.
You may see me but you will not remember, I'm not really here so quit reading this. I mean it, quit reading this. All right you PI$$ANT, I said quit it!!!!! If you don't stop right now I'm going to go all keyboard commando on you!!!!!



sr15
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/14/2003 5:34:49 PM
Originally Posted By Merlin: I've decided to add 2 more ground rods in front of the house. One will be right in front of the small crawl space vent where my current ground wire goes and one to the right of it. This will make a total of 3 ground rods, with the 2 new ones further from the house and beyond the drip line. I will also extend both panel ground wires to tie directly into the main/middle rod (right now they are spliced together and have a 20 foot lead. Before I do anything, the first thing I will do is to see if I can get an accurate reading on the current resistance between my panel ground bars and the current ground rod. I'll then compare that figure with the new configuration.
Just make sure you bond all of the ground rods together. I'd recommend using copper 5/8" 8' ground rods.
sr15
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/14/2003 5:49:07 PM
Originally Posted By Blaster3094: Both the neutral and ground bus in your breaker box are at equal potential aren't they?
Only if the meter base and the breaker pannel are in close proximity to each other, in which case the neutral and ground busses will be bonded together. If the meter base and the breaker pannel are not a within a "reasonable" distance to each other, then the the neutral and ground busses will not be bonded together at the breaker pannel. In this case, the neutral bus and ground bus will be a different potentials. The difference in potential will be the resistance of the neutral wire/conncetions between the breaker box and the meter base X the current flowing in the neutral conductor (V=RI). No current should be flowing in the ground wire between the breaker box and the meter base, so it's potential is zero.
So if you have a good earth ground for your house perhaps some current would follow that path?
Yes. But in a proper installation, the resistance of the neutral conductor between the transformer and the meter base will always be much much less than the resistance between the grounding electrode at the meter base (ground rod) and the grounding electrode at the transformer. So, the majority of the currrent flows through the neutral conductor.
sr15
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/14/2003 6:29:55 PM
[Last Edit: 1/14/2003 6:31:37 PM by sr15]
Originally Posted By Guncrazy223: I beg to differ with the idea that MOv's are not a good way to provide surge protection. I worked for a place that designed and built MOV's for power lines. We also built MOV's for things like MRI machines. A GOOD MOV, can withstand multiple strikes and can last a very long time. How often do you think a power company want's to be replacing these things. MOV's biggest problem is heat from a lot of time overvoltage unlike normal resistors that have an increase in resistance with heat, MOV's are the opposite so if they get hot they conduct better and at some point they will burn up. It's cool how powerful an MOV can explode when hit with 10,000 amps multiple times. I helped design an arrester while I worked there so I did some research into this and I didn't find another way that was economically feasable as surge protection. Though some people like sparkgaps in conjunction with MOV's.
It's widely accepted that MOV's degrade when subjected to surge currents. That's just a property of the baked metal oxide powder. Typically, the clamping voltage decreases after each surge current, but it can increase. It is recommended that MOV's be replaced after this voltage changes by +/-10%. I agree MOVs can be designed to withstand multiple surges, but the cheap ones found in the cheaper surge protectors are not. MOV's that can withstand high current surges or multiple surges are not cheap. Also, I believe most high voltage TVSS use silicon carbide and not zinc oxide. I think silicon carbide is a much more robust material.
Goshawk
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/14/2003 8:52:10 PM
As a professional electrician and code inspector, the cheapest way to answer your question is to hire an electrician. There are many good replys to your question posted here, but if you are not familiar with grounding and bonding it would be easy to overlook something that may not give you a problem now, but could surface in a few years. JMHO.
Merlin
Member
Offline
Posts:
Feedback: 100% (1)
Link To This Post
Posted: 1/14/2003 8:58:08 PM
I tested the connections between the panel ground bar and the ground rod. Here's the results: - 0.1 ohms for the multimeter itself (I bought a new digital tester, there's no apparent way to "zero" out this tester. - .5 ohms for the multimeter plus test cables (14 ga extension cord). - 0.7 ohms from the ground bar to the ground rod, including the multimeter and test cables So, I have good connections to ground rod, but no way to know if there's a good connection to "ground". For that, I bought 2 5/8"x8" copper coated ground rods and +24' of #4 awg solid copper wire. After I'm done, I will have tied both panels directly to a new middle and "wet" ground rod, tied all grounds to this wet rod, added one more "wet" rod and connected the gas pipes to the grounding system and significantly shortened the main panel ground wires since the current one goes a distance through a crawl space vent vs. directly through the wall. Thanks for all the help and advice! Thanks, Merlin
sr15
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/15/2003 1:08:23 AM
Originally Posted By Merlin: I tested the connections between the panel ground bar and the ground rod. Here's the results: - 0.1 ohms for the multimeter itself (I bought a new digital tester, there's no apparent way to "zero" out this tester. - .5 ohms for the multimeter plus test cables (14 ga extension cord). - 0.7 ohms from the ground bar to the ground rod, including the multimeter and test cables
Sounds good to me.
So, I have good connections to ground rod, but no way to know if there's a good connection to "ground". For that, I bought 2 5/8"x8" copper coated ground rods and +24' of #4 awg solid copper wire. After I'm done, I will have tied both panels directly to a new middle and "wet" ground rod, tied all grounds to this wet rod, added one more "wet" rod and connected the gas pipes to the grounding system and significantly shortened the main panel ground wires since the current one goes a distance through a crawl space vent vs. directly through the wall.
You'll probably have the best grounding system on the block now [:)].
Tonkaman
Member
Offline
Posts:
Feedback: 100% (1)
Link To This Post
Posted: 1/15/2003 2:41:13 AM
Since you have already gone to this much trouble, you might as well go all the way overboard. Isolate grounds from each of your light fixtures, convience outlets, computer outlets, etc. and run them to grouped spaces on the neutral bus. Then bond the reinforcing bars in the foundation of your house to the grounding system. Make sure all the lugs and bolts are torked on your panel boards. Hire an electrical testing agency to verify your grounding system and check for hot spots.
Merlin
Member
Offline
Posts:
Feedback: 100% (1)
Link To This Post
Posted: 1/15/2003 8:03:23 PM
Guncrazy and SR, What are some good, but not overly expensive surge protectors for residential use? I just bought a few Woods surge protectors good for 750 and 1000 joules. Are these any good, if not, why not? I've spent some time educating myself on surge protection since we lost our downstairs gas pack and almost all of our phones a couple of years ago due to a close lightening strike. The field appears to be full of advertising BS. Please advise. Thanks, Merlin
sr15
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/15/2003 9:23:35 PM
[Last Edit: 1/15/2003 9:27:40 PM by sr15]
Originally Posted By Merlin: Guncrazy and SR, What are some good, but not overly expensive surge protectors for residential use? I just bought a few Woods surge protectors good for 750 and 1000 joules. Are these any good, if not, why not? I've spent some time educating myself on surge protection since we lost our downstairs gas pack and almost all of our phones a couple of years ago due to a close lightening strike. The field appears to be full of advertising BS. Please advise. Thanks, Merlin
After spending 10 years on the fire department, I learned that nothing is safe from lightning. But you can do a few things to help minimize damage. Installing additional ground rods and having a low impedance grounding system definitely helps. I believe that the Woods surge protectors only use MOV's, which will work fine for for first few brief overvoltages, but are useless during a lightning strike (direct or indirect). I was using a similar surge protector on my computer when lightning struck a few houses away. Everything connected to the power supply failed: the mother board, the processor, the hard drive, the cd rom drive, the zip drive, the cooling fans, and the floppy drive. The only thing that still worked was the surge light on the surge protector indicating that there had been a surge. So, now I am using a [url=http://catalog.belkin.com/IWCatProductPage.process?Merchant_Id=&Section_Id=71&pcount=&Product_Id=100991&Section.Section_Path=%2FRoot%2FPowerProtection%2FComputer%2E%2E%2Eotection%2F]Belkin F5C980-TEL[/url]. It's rated at 2960 Joules and has an ulimited connected equipment waranty and a data recovery waranty. I'm using this surge protector because it incorporates passive filtering in addition to MOV's. I believe it also uses TVS's, which do not degrade with each surge. I plug my UPS into this surge protector, which also has surge protection (probably just MOV's), and then plug my computer into the UPS. You can get this surge protector at [url=http://www.officemax.com]Office Max.[/url]
thebrain
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/15/2003 10:22:45 PM
In your original post you said they were grounds from your garage panels. Are theses panels sub panels? That is do they drive their power from another panel? I am farley certain, with out an answer that the 100A panels probably is. Any way if they are sub panels, they should have a four wire cable coming into them. Each cable will contain 2 hots(black or red wire) 1 neutral(white or gray) 1 ground(green or bare metal). The ground from the feeder cable should run continuously all the way back to the panel of origin. Where it is bonded to the grounding electrode system. That is all the grounds on premises are connected via terminal strip. Your grounding electrode system should have a wire running to Building steel, water main with in 5 feet from where it enters the premises, and a ground rod, possibly 2 ground rods. All this of course is on a new build, If you live in an older home it is most likely not up to date. And has been hacked on by everyone who owned it. I am sorry you had to read another long post. I do hold an electrical license in the state of Michigan, and would be glad to help if I can. My email is available threw this sight.
Kroagnon
Offline
Posts:
Feedback: 0% (0)
Link To This Post
Posted: 1/16/2003 2:05:42 AM
Originally Posted By MickeyMouse: Power surges from things turning on or off should NOT result in dimming of lights, lights getting brighter or ANY safety ground current. If you have any safety ground current at any time, (other than lightning) find the cause and FIX IT.
Lights shouldn't dim during power surges? Whatcha smokin there? [:D] If there's alot of current draw on a single circuit (say a 20A run on 12AWG) you're going to get some voltage drop.
Merlin
Member
Offline
Posts:
Feedback: 100% (1)
Link To This Post
Posted: 1/16/2003 7:55:13 AM
Thebrain, These are not subpanels, they are the main panels for the house, one is 200 amp, the other 100 amp. Both are fed by separate 3 wire AL from the street through the meter. I'm the only one who has owned this home. The original ground wires from the 2 panels were found to NOT be connected to anything in the crawl space about 2 years ago or so. There is, however, a #4 AWG ground wire hooked up to the ground rod outside that I have no idea where it goes. I have since hooked both ground wires together, hooked one to the copper water pipes and took another ground wire to the existing (and dry) ground rod. I plan to add to this configuration in order to improve the grounding system. Thanks for the help. Merlin