house wired without separate ground - problem?

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All right, I'm feeling mildly dumb and a little sheepish not to mention slightly sick here... just bought a house for the first time less than a month ago, and knew that it had some minor wiring "issues" but now that I'm assessing what I have it appears that there are bigger issues than previously anticipated. Anyway, here's the deal. House is a two story colonial with full basement, built late 1940's. Excellent structural condition, lovely hardwood floors albeit in need of a refinishing. Paid for a home inspection prior to placing a bid on house. Inspector noted some electrical items that would be against code now for new construction but nothing major (things like clothes washer sharing a circuit with other receptacles, lack of GFCIs in the kitchen, etc.) all receptacles in house are three prong type and tested OK with cheap little $5 circuit tester. All visible wiring was old BX w/ cloth covered conductors and inspector said that grounding through the armor of the BX while not the way we do things now was perfectly OK. So I was feeling pretty good about things electrically, and that gave me a good feeling about the house, as I automatically anticipated issues with lack of grounds etc. in a house of this age. Well some of the receps. were a little loose and old looking so I bought a pack of new ones and proceeded to replace them. Basement went fine. Got to the first floor and identified some issues that will be easy to rectify. Then I got to the three oldest circuits in the house, one of which started life as the general first floor circuit and another the general second floor circuit (the latter of which still serves the entire second floor.) The third is a lighting only circuit which serves the lights at the stair landings. It appears that throughout the house wherever the wiring was hidden behind plaster it was run in NM not BX and there is no grounding, period. I don't have a big problem with that on a lighting only circuit but the receptacles installed on the first and second floor are grounding type and it appears that the ground is provided by a jumper at each receptacle between the ground terminal and the neutral. I realize that *theoretically* this is functionally identical, but this isn't the way we do things now, so it bothers me a little bit.
questions:
1) is this actually an acceptable method of retrofitting receptacles to grounded type? I suspect not, but you never can tell.
2) if not, is this the kind of thing that would generally be covered by a home warranty? We did spend the $$ for one, although AFAIK it generally only covers things like appliances etc.
I don't blame the inspector for missing this one; he would have had to pull a receptacle either on the south side of the first floor or somewhere on the second floor to identify this issue; there's a lot of wiring visible in the basement but it is all either BX or obviously recently added Romex which does contain a ground, so there was no reason to believe that this wasn't consistent throughout the house. However, the transition from exposed BX to hidden NM seems to be original to the house as far as I can tell; I wonder why that would be?
Any help, thoughts, advice, etc. greatly appreciated.
thanks,
nate
(it's a good thing the girlie was planning on repainting, I guess...)
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Nate Nagel wrote:

Definitely not kosher to connect the receptical ground terminal to the neutral terminal.
Consider replacing those recepticles with GFCI types with "ground not connected" labels applied to them.
If you can definitely confirm upstream and downstream recepticals you could use GFCI recepticals in the upstream ones and continue using recepticals without ground holes on the downstream ones, or use grounding type recepticals with the same "ground not connected" stickers on them.
As always, clear this stuff with your local electrical inspector he/she may or may not go along with my ideas.
Jeff
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It is not correct to wire outlets in that fashion, and I wouldn't expect your home warranty to cover it, because it's not "broken" or something that broke down, just improperly wired outlets. For people protection you can install GFCI outlets, but it doesn't help for equipment that needs to be grounded, for that you'll need to run grounded cables to those locations

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What equipment "needs" to be grounded?
You may find that today the answer is: not much!
Most audio/visual stuff (TVs, Stereos) doesn't have a ground.
I have a window A/C that has a GFCI built into the plug (which does have a ground). But there isn't a ground wire to the case of the A/C.
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Things like computers "need" to be grounded

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Not at all.
They work just fine, thank you, with a "floating" ground. Often, however, where these is a ground provided there is a network which provides a small leakage path between BOTH power conductors and the chassis (ground). The effect of this network would be to cause the chassis get a voltage on the order of 55 volts. There is no shock hazard and the leakage of even several of these systems is not likely to trip a GFCI.
There is a lot of "tradition" here.
When IBM started making PCs they had a ground. When folks starting making audio/visual stuff include stereos and TVs, there usually wasn't a ground. But both classes of equipment have user exposure to the "chassis." In the audio/visual stuff its from the "RCA" female connectors. In the PC world it's the connector shell including the mouse, keyboard, USB stuff, printer and serial interface.
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On Fri, 20 Oct 2006 08:04:56 -0400, John Gilmer wrote:

There's a big difference between A/V equipment and computers. Well, at least in Europe, I don't know much about US regulations. Most A/V stuff has reinforced or double insulation. That's why they have a plug without ground. Computers (except some laptops) usually have only 'normal' insulation. A single fault in the insulation can create a connection between the live pole and the cabinet. Without a grounded cabinet, that could be lethal. With grounded cabinet, you just blow a fuse.
In case of fire or other damage, the insurance company can give you a hard time, if they find out that you have class I equipment connected to a socket without ground.
BTW: the 55 V you mentioned (115 V over here) is more than enough to blow a serial or parallel port when connecting a grounded printer to a non-grounded PC. For me, that's also a good reason to ground my PC.
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Maurice Janssen wrote:

I found it interesting to discover that some two prong "wall wart" transformers have a high value resistor (in the order of 500K ohms) connected between the wide plug blade and the secondary of the transformer to drain off static charges from the chassis of whatever it is they are powering.
That large a resistance could only deliver about 250 microamps of "shock current" if the receptical it was plugged into was crosswired hot to neutral.
Jeff
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Not really. In both cases there is a transformer isolating the power from the load. I grant that the "switching" power supply used in PCs has a good amount of circuitry (the "switches") before the transformer -- "they convert the incoming AC to DC and then convert it to a higher frequency. At higher frequencies the transformer can be made a LOT smaller. In switching input also lets the power supply accomodate a very large change in input voltages without problem. There is no good reason why "they" could not make a PC power supply that made the PC as safe as your TV without relying upon a ground.
Again, I point out that LG (the Korean company, formerly known as Lucky Goldstar) now ships it's Chinese made room air conditions with a GFCI built into the plug but with NO ground wire going to the chassis.
I also like to point out that you are somewhat safer if metal objects in your environment "float" rather than be grounded. If your left hand is resting on a well grounded object and your right hand touches something electrically HOT, you may get a fatal shock. If your left hand is resting on a "floating" metal object you might get a little "tingle" when your right hand hits the HOT wire.
Tradition counts for a lot is setting standards. BUT, had cheap and reliable GFCI technology been available when electric power was "new" it's quite likely that "grounding" may not have been as important.

True. Nonetheless, it's possible to make a PC power supply that is as safe as that in your television or DVD player. The next time I have both a dead PC power supply and a dead VCR I will open both up and see whether the PC supply is any more likely to generate a HOT to Ground cross that the VCR.

Unless it was the cause of the fire, the insurance company will not say a thing. Moreover, codes permit sockets with ground openings that are not grounded so long as: 1) the circuit is protected by a GFCI; and 2) there is a "not grounded" label applied. Read the installation instructions on your GFCI (I may be making an incorrect assumption about GFCIs "over there."). In the States, the insurance companies have better have a VERY good reason to give your a "hard time." A company that drags its feet over a payment risks paying fines to the regulators and risks being successfully sued by the insured with truly massive "punitive" damages.

No. It would be current limited. Likewise, if you rub your feet on the carpet in winter and build up a 20,000 volt charge (which happens) you likely would not fry something it you touch a signal pin. It's all a matter of how much energy you can dump into the interface.
Your grounded printer would "ground" your PC. No harm, no foul.

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It's also possible that the wiring could be knob-and-tube in a house of that age.
Bob
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Bob F wrote:

No, it's definitely some early type of NM, although it may not be officially designated as such. There's two plastic-insulated conductors (that must be a pretty early use of same; as far as automotive stuff goes I believe the transition was made about 1955 - at least it was for Studebaker; I have a '55 coupe which (fortunately) has plastic insulation on the wiring) in what appears to be a tar-impregnated cloth jacket. But no ground.
I really, REALLY don't want to have to rewire two complete circuits, although at this point it kind of looks like I'm going to have to. I might even have to involve a *gasp* electrician due to the magnitude of what this project looks like it's shaping up to be, which makes my Y-chromosome cower in shame. I suppose I could just install new non-grounded receptacles ahd that would be technically correct, although then I'm back where I started, as there's computer equipment on the second floor, and a UPS theoretically should have a ground... also would feel better if the stuff in the bathroom were grounded (although I was thinking of rewiring the bathroom anyway to meet current code with a dedicated circuit, GFCI, etc. which is somewhat doable as there's a small chase going down to the basement behind the bathtub, and an access panel, so it's "just" a matter of getting a cable from behind the bathtub up into the attic and then back down to the light switch...)
I suppose it's not acceptable to cheat and ground stuff to the nearest water pipe...
nate
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Nate Nagel wrote:

You can still buy ungrounded receptacles and put things back like original. Most circuits don't really need a ground, like the upstairs bedroom convenience outlets.
Where you really need grounds (bathroom, kitchen counters near the sink, your computer UPS, etc,) you can run a separate green wire back to the service panel ground (or to the nearest grounding electrode conductor, if that is easier.) The ground wire does not have to run with the current-carrying wires if you are updating old work.
You can also install a GFCI breaker and then use 3-wire receptacles, leaving the ground terminal disconnected. In this case, you technically need to put a sticker that says "GFCI Protected. No Equipment Ground." on each of the grounding outlets that has a floating ground.
You can also protect circuits by wiring them thru the LOAD terminals of a GFCI receptacle.
The most practical solution will probably end up being a mixture of these methods. HTH :-)
Bob
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i would run a seperate ground wire to the effected outlets.
how many are a problem? 5 10 50?
most older homes have few outlets, might be time to upgrade.
do not connect grounds to neutrals in the right situation it can kill........
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zxcvbob wrote:

that may be doable at least upstairs; is it kosher to run, say, THHN without conduit or greenfield or would I need some kind of plenum rated wire? Please excuse the dumb questions; I know a lot about fire alarm but just enough to be dangerous about plain old electrical stuff. Since I really like this house (and paid enough for it!) I'd like to "do it right" whenever possible, and certainly would like to be able to say with a straight face to any prospective buyers in the future that everything is up to snuff.
nate
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Nate Nagel wrote:

From what I can tell, the electric code is silent about that. I just run a #12 green THHN / THWN-2 wire inside the wall cavities, staple to the ceiling joists, etc. I run them as neatly as possible and where they are unlikely to be physically abused. I ground them at a big split-bolt connector on the main grounding electrode conductor a couple of feet from where it goes into the electric panel.
I have an older house, and I'm trying to get one properly grounded duplex outlet in each room, and I don't worry about the ungrounded convenience outlets. All the basement, bathroom, and utility room outlets are grounded and GFCI'ed (except the outlet for the freezers.) All the kitchen outlets are grounded except for one that I couldn't get a ground wire to so I installed a GFCI receptacle. (the one that I couldn't ground just happened to be the outlet close to the sink)
Bob
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zxcvbob wrote:

Thanks to you and to the others who replied. I have a coworker who is a master electrician as well and he also suggested the separate ground wire, so I think that that may be the plan of attack for the first floor. Here's what I'm thinking:
-buy some new circuit breakers. I have four spare spaces in the breaker panel, but I'm going to see if I can get some half-height breakers just in case I want to add a 240V circuit in the future.
-split the washer and dryer onto their own circuits. (they are currently sharing circuits; the washer with the hall lighting and the dryer with the dishwasher.) Also run a dedicated circuit to the (gas) stove (currently shared with the hall lighting and clothes washer.) Should this be 20A or is 15A sufficient? I was thinking 15A would be OK but if current code recommends 20A that's what I'll do.
-If feasible, provide a new 20A circuit for a single receptacle on the kitchen counter that's currently shared with the 1st floor lighting ckt. (the other is already on a 20A circuit, and I've installed a GFCI receptacle)
-Again, if feasible, provide a new 15A circuit dedicated for the bathroom. cut box out of wall and replace single gang box with light switch with double gang box for light switch and GFCI receptacle. Leave pull string up to attic for future installation of an exhaust fan.
-On the first floor, run a single green 14AWG THHN from breaker panel to receptacles coming up from below and then dropping back down again, working my way around the perimeter of the house. One homerun for each circuit (there are two.) Light switches and light fixtures remain ungrounded; there seems to be no way to deal with those short of breaking up some very thick and sturdy-looking plaster.
-On the second floor, either follow the same plan as above, but dropping down from within the attic, or else find the homerun and ground that back to the breaker panel using the chase behind the bathtub and then completely rewire the rest with 14/2 Romex from the attic (should be possible, although I suspect this house was wired "old style" with switch legs dropping down from the ceiling light fixtures so I may leave the light switches ungrounded.)
comments?
I'm starting to think that maybe I can do this (assuming, of course, that She Who Must Be Obeyed displays an aptitude as a fish tape operator,) although I'm wondering if I'm approaching the point at which I need to pull a permit. I certainly don't want to piss off the various local agencies as I do need to deal with them at work.
nate
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Nate Nagel wrote:

You are on the right track to just add the ground wire where possible, it is much easier. My wife has, over the years, become extremely adept at grabbing fishtapes in wall cavities with bent coathangers. WIthout her help, I would still be doing some projects that have been completed years ago. I prefer metal boxes with ears that pull out when the screws at the side of the box are tightened. The plastic boxes with the tabs that rotate out don't have as much area pushing against the back of the sheetrock/plaster as the flat tabs on the metal boxes. Also, the plastic boxes do distort their shape a little while the metal boxes are more rigid.
H. R. (Bob) Hofmann
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snipped-for-privacy@att.net wrote:

Where do you find metal old work boxes? My local "big box" hardware stores do not have them, although I've seen some of the contractors I work with using them, I believe they get them from supply houses where they have accounts.
nate
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Lowes and Home depot both sell them. As do most all other hardware stores.
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"N8N" < snipped-for-privacy@hotmail.com> wrote in message
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Don't have a Lowe's, but Home Despot doesn't have them, at least not out and on the shelf. Unfortunately the quality of help at Home Despot is... not so good, so they look at me blankly when I ask questions.
nate
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