Is this 2-wire Receptacle Ground Correct?


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Old 03-28-07, 10:37 PM
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Is this 2-wire Receptacle Ground Correct?

I live in a house built in 1960 and it has 2-prong receptacles (no ground wire) throughout. I have 2 computers that need grounding and so I had an electrician to come in and run a green ground wire (#12) from 2 new 3-prong receptacles. The new ground wire runs (outside under the eaves of my house) from the 2 new receptacles to the service which is in my carport.

However, I noticed that the end of the green ground wire is connected to the pipe (using a copper band) that enters the top of the meter which is connected to the breaker box right below the meter.

Is this correct? I've read in some of the posts on this site that "The only way to provide grounding to ungrounded receptacles is to add a green copper ground wire from the receptacle back to the circuit panel box (the ground bar in the panel supplying the circuit.)" Am I looking at this incorrectly?


Also, I've read in some post that "Grounding old receptacles is a waste of time compared with adding new." Would you please explain this to me? I would think that adding the green ground wire would be much less effort than installing new circuts (although this would be better). What am I missing here?

Thank you
 
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Old 03-29-07, 03:54 AM
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No it is not correct. All grounds should terminate inside the breaker panel on the neutral/ground buss. But actually, you went to a lot of trouble. You likely have ground conductors in your house wiring. It was wrapped around the cable and the box clamp was tightened on it. That is not current code, but it was a ground connection. To make it better, you can unwrap the ground wire and pull it into the box, tie all grounds together and to the box and the outlet.
 
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Old 03-29-07, 04:14 AM
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NEC allows a variety of ways to ground equipment; one of those ways is through properly bonded conduit, but I don't believe that's acceptable in this case. I also question the wiring practice- did he run THWN exposed through the eaves? So long as the green wire is solidly grounded, it should be "safe" for the time being, but does not sound legal, and there seems significant risk for that wire to degrade or be damaged in the future, leading to shock hazards down the road.

Did you pull a permit and have this inspected?

In the future, another acceptable way of giving yourself 3-prong outlets is to replace the first receptacle in the string with a GFCI receptacle, and the rest with traditional 3-prong receptacles- this will not ground the plug, but WILL eliminate the chance of a fatal electric shock. The protected plugs must be labeled as ungrounded, but stickers will come with the GFCI. It's an easy DIY task, and will only run you about $20/room
 
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Old 03-29-07, 04:25 AM
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grover,

Using GFCIs will not provide a ground, as you stated. However it will not protect against a "fatal electric shock." Even with a GFCI, if you place your heart between the hot and neutral wires you could get yourself killed. The GFCI does not know if the current is running through your body or the device plugged into the receptacle. Further, since the poster specifically stated he wanted a ground for his computers, using GFCIs is not the right answer.

ThePeach,

It is usually no more work to add new receptacles than to add ground existing ones. Yes, NM cable is more expensive than a single ground wire, but the time spent running cable is about the same.
 
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Old 03-29-07, 06:25 AM
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Thanks to all for the responses

Let's see if I understand...

First of all, the the green ground wire the electrician ran should terminate inside the breaker panel on the neutral/ground buss...Correct?

*As it exist, does this provide a grounded receptical for my Computers (do I really have a good equipment ground) ? ("NEC allows a variety of ways to ground equipment; one of those ways is through properly bonded conduit"...so, this does not apply to my situation??? correct

*Does it represent an unsafe condition (for me and/or for my computers)?

Second, the green wire is not run inside the eave, but rather on the under-side of the eave of the exterior wood surface. Should this be better protected?

There are no ground conductors in my house ( no other wire "wrapped around the cable and the box clamp")...

The electrician said that because of the very limited space in my attic (it's a very shallow roof (old military housing) and to install new wiring (circuits) he would need to run conduit from the service to the receptcals (on exterior of house) which is very expensive. So, based on my level of ignorance, it seems that just running new wiring is not an option...agree/disagree??

Cost aside, should I have new wiring and circuits?

Thanks for any futher comments on this
 

Last edited by John Nelson; 03-29-07 at 08:32 AM. Reason: eliminate quote
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Old 03-29-07, 06:32 AM
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I cannot fathom a situation where there are no options but to run cable outside. The cheapest and easiest option may be to run cable outside, but I believe that is a way top run cable inside.

Try a different electrician.
 
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Old 03-29-07, 06:40 AM
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Thanks for the fast response...

I'm going to get some quotes from a couple other electricians to see what costs are involved.

Thanks very much for your help
 

Last edited by John Nelson; 03-29-07 at 08:31 AM. Reason: eliminate quote
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Old 03-29-07, 06:44 AM
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Although your current situation may violate a few codes, it is nevertheless not overly dangerous and it is probably effective in protecting your computers. I would plan to get this fixed at some point, but I would not consider it an urgent fix.
 
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Old 03-29-07, 06:58 AM
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[QUOTE=ThePeach;1150224]

"a green ground wire (#12) from 2 new 3-prong receptacles".

This is the correct size (and color, although it could be bare) for a 20A equipment grounding conductor, so far so good.

"The new ground wire runs (outside under the eaves of my house) from the 2 new receptacles to the service which is in my carport."

This is OK as long as the wire is not subject to damage as it leaves the receptacle and attaches to the main panel.

"the end of the green ground wire is connected to the pipe (using a copper band) that enters the top of the meter which is connected to the breaker box right below the meter".

This is a (code related violation) problem.

The code (2005 NEC 250.130(C)) allows connection of this grounding conductor to:
"Any accessible point on the grounding electrode system".
This includes the large copper wire (GEC) that runs to the grounding electrode (ground rod, footer steel, water line (that's used as a grounding electrode), or the grounding electrode itself.

"Any accessible point on the grounding electrode conductor".
This is the large copper wire that runs to the ground rod (grounding electrode).

"The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates".
The new receptacle ground wire either has to go back to the service (as described above) or to the ground bar in the breaker panel where the circuit originates (the circuit that feeds the new receptacles).

"For grounded systems" (as yours is) "The grounded service conductor within the service equipment enclosure".
You can attach your (new) equipment grounding conductor directly to the grounded service conductor by using a listed connector.

I don't see the service conduit (where your electrician made his connection) as a "permitted" place to make this grounding connection.
The ground that he installed may work, I wouldn't know without seeing it myself, but it's not installed per the electrical code.
Also, I'm not sure that the "copper band" that the electrician used is listed for the use.

hope this helps
steve
 
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Old 03-29-07, 08:27 AM
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Thanks for the nice explanation Steve. I'm studing your response as well as the others to make sure I understand your comments. (am I allow to post a picture on this site?

The conduit to the meter where the electrician connected the new ground wire (using copper band) has a ground wire that comes from a grounding rod (about 10' away) that has a ground wire that runs from the Ground Rod to the Meter and then into the breaker box (that's what it looks like to me). So, should I have him return to connect the ground wire to the breaker panel on the neutral/ground buss?

Thanks for your generous help on my issue
 

Last edited by John Nelson; 03-29-07 at 08:30 AM. Reason: eliminate quoting
  #11  
Old 03-29-07, 10:16 AM
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Peach

It is possible that this connection point may be allowed in your juristiction. I am a little confused what you have though. Are you saying there are two copper grounding electrode conductor wires..... one from the ground rod and is attached to the service mast. Then another one from the ground rod to the meter then it goes from the meter to the breaker panel (main disconnect enclosure)?

A grounding electrode conductor (this is not what the electrician ran) can be attached on the load side of the service drop, at the meter can or at the service disconnect. It would be odd in my opinion to have two grounding electrode conductors ran from the ground rod...one to the service mast and one to the meter and main disconnect.

Can you post a picture on a photo site and give us the link to it?

I would have to speculate but the electrician gets the benefit of the doubt in my opinion. It could be that since a grounding electrode conductor is attached to the mast for an overhead drop that he is allowed locally to terminate the equipment grounding conductors there. I have never seen it done this way. But things vary from one area of the country to the other. I'm not sure why he just didnt take them on into the breaker box and attach them to the neutral bus.

I'm attaching a graphic from Mike Holt for reference maybe you can explain how yours relates to it. Look at #3 as your breaker box. This graphic is the grounding electrode system not the equipment grounding that your electrician ran. But it will help us with what you have there. Explain how yours is done and where the electrician connected the equipment grounds. Copy and paste the location.

http://www.mikeholt.com/onlinetraining/page_images/1113854601_2.jpg


Roger
 
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Old 03-29-07, 01:24 PM
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Thanks Roger, Sorry to make this so confusing but here is a link to a picture I took where the Green Ground Wire connects to the meter conduit:

http://img370.imageshack.us/img370/7810/groundwireconnectiontoswz4.jpg

Here's my configuration/Situation:

1. I had an electrician install two new 3-prong wall outlet receptacles (one for each of my computers which are in different room separated by about 15'). While installing these two new receptacles, he installed a Green Ground wire that goes from the receptacle (He drilled a hole through the Brick/morter into the area where the recptacles are. From the receptacles he ran a green ground wire up the exterior side of the house to the eave and ran it under the exterior portion of the eave to the other side of my house where the service meter/Breaker Box is located (see picture).

2. The black wire you see attached with a metal band is a ground wire that my Internet Service Provider (ISP) installed some years ago. It comes from the internet cable junction boxes on the back of my house (mounted under the eave) and connects to the Meter conduit that you see in the picture.

3. The Ground Rod for the electrical service is a galvanized rod that has a ground wire that runs from the rod to the Meter and I'm guessing that it then runs into the Breaker Box but I'm not sure.

Here is picture inside & outside Breaker Box:

http://img370.imageshack.us/my.php?image=breakerboxopenviewbq6.jpg
http://img387.imageshack.us/my.php?image=meterandbreakerboxua4.jpg

Here is picture of Service Ground Rod

It runs up the wall in conduit to the oppisite side where it enters meter.

http://img502.imageshack.us/my.php?image=servicegroundrodce4.jpg

Here is picture of Mast:

http://img387.imageshack.us/my.php?image=servicemastbi4.jpg


Thank you for your help with this
 

Last edited by John Nelson; 03-29-07 at 04:18 PM. Reason: eliminate quote
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Old 03-29-07, 02:31 PM
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> Using GFCIs will not provide a ground, as you stated. However it will not
> protect against a "fatal electric shock." Even with a GFCI, if you place
> your heart between the hot and neutral wires you could get yourself killed.
> The GFCI does not know if the current is running through your body or the
> device plugged into the receptacle. Further, since the poster specifically
> stated he wanted a ground for his computers, using GFCIs is not the right
> answer.

racraft, what are you saying? That because GFCI don't protect again L-N faults, that they're useless and don't protect against fatal electric shock? I don't know what kind of faults you're picturing, but casual contact with faulted equipment is NOT going to cause an L-N short through a person's heart. For that to happen, they would have to grab the neutral in one hand and the live wire in the other, but that's not what GFCI are to protect against. If someone is grounded (standing barefoot in a puddle on concrete, or touching a pipe, etc, you know I'm talking about) and comes in contact with an energized component, that GFCI is going to save their life, regardless if there is a ground wire on the green screw or not.

The ground wire provides a fault path for fault current, and it designed to trip the breaker in a short circuit. But it will not trip the breaker in high-impedance fault, such is common in wet areas, or when the fault connection is made through the human body.

re: computers and GFCIs- computers aren't unique. 3-prong plugs are on appliances because UL required it for safety, usually because of a metal case that can become energized and always because there is something in that appliance that UL says requires a ground. NEC understands this, and allows GFCIs to be used on ungrounded outlets because sure, the case will float, but it's not an electrocution hazard if the GFCI limits the potential shock to 5ma. The best solution would be GFCI *and* a ground, but that's not always practical. (Computers work just fine on 2-wire outlets and adapters, btw, it's just not safe!)
 
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Old 03-29-07, 02:51 PM
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A GFCI will protect against a line to ground fault, and in that regard will protect against a fatal shock. However, it will not protect against ALL shocks. My post should have stated that a GFCI receptacle will not protect against ALL shocks.

Computers have grounds for one or two reasons. Those with a metal case have a ground because of the exposed metal. Others simply have the ground to provide a reference point for signals. A computer with a three prong plug needs a grounded circuit. Not only to be safe, but also for proper operation.
 
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Old 03-29-07, 03:02 PM
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I agree with you in principle, but in practice, the case floats close to ground and 100BaseTX and other residential communication lines work just fine. More sensitive serial connections just aren't used much anymore.

9 times out of 10 in this situation, the GFCI is replacing a 2-prong adapter anyhow...
 

Last edited by grover; 03-29-07 at 04:47 PM.
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Old 03-29-07, 03:41 PM
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Well..... it appears that what they are banking on is the connection of the mast to the grounded conductor (service neutral) via the messenger and the meter can bonding with the main breaker panel providing the ground fault path. The messenger is the wire rope cable which serves as the service neutral and supports the service cables for the span from the transformer to the mast weather head.

I would say this isn't the worst of things that could have been done. Everything being right...ie...all bonding correct your breakers should trip on fault and computers should have their ground reference.

I do wish the electrician had cleaned the paint a little better where the strap is, but this isn't the primary grounding connection.... the bolt penetrates the paint and mast and the lock nut secures the green ground wire.

My opinion is this is a real gray area as far as code. I think for your peace I would just put in a call to the local codes department get the e-mail address for (if possible) the inspector and send him these same pictures and see what he has to say. I'm not sure if there will be any permit issues as a result but at least your in their good graces one way or the other.

Roger
 
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Old 03-29-07, 04:07 PM
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Thank you Roger for the nice explanation and comments.

What would be a good way to test to ensure I have a good ground for my Computers. I have a digital multimeter and one of those inexpensive outlet testers . Can you reccommend a site that explains ( has a simple tutorial) how best to do this. What reading with the digital multimeter indicates that I have a good ground (25 ohms or less??? closer to zero??)

Thank you
 

Last edited by John Nelson; 03-29-07 at 04:18 PM. Reason: eliminate quote
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Old 03-29-07, 04:21 PM
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There is no way practical way for a homeowner to check for a good ground. But most surge suppressors have a light on them that indicates that it is grounded and/or that it is providing surge protection. That at least provides limited assurance that you have basic protection.
 
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Old 03-29-07, 04:48 PM
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Thank you John...

I have each Computer connected Via three prong cord) to a Belkin F6C1100-UNV (1100VA/660W) UPS that is connected to the new grounded 3-prong receptacle. The UPS has a Site Wiring Fault indicator that has a light/LED that turns red if there is either no ground circut or a reversed polarity. Both USPs show that there is no Site Wiring Fault.

I should also note that because of ESD concerns (I live in a dry climate), I have a 3M Velostate Electrically Conductive Mat (4'x6') that lays in front of my computer to help dissipate the charge. The mat has a ground wire with allegator clip that is connected to the center screw on the new 3-prong receptical. (The allegator clip has a little eyelet screwed on to fasten to the screw to ensure it does not come loose. The mat has a second ground cord with a wristband that I use when working on the inside of my computer and when I'm not the wrist band clips to my desktop where I can touch it before touching my computer.

Now for my conductive safety shoes

Thanks for the great review and comments.
 

Last edited by John Nelson; 03-29-07 at 05:22 PM. Reason: eliminate quoting
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Old 03-29-07, 05:17 PM
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Good point about the surge suppressor! I'd forgotten about TVSSs- they most definitely do not work on ungrounded GFCI outlets.

Sounds like you're pretty well set to protect your PC from static charge, ThePeach
 
 

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