pulling 115v from a 230v and adding a ground

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Old 12-08-09, 10:36 AM
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pulling 115v from a 230v and adding a ground

House built 1954. 115 is two wire and 230v is three. I have added a few new 115 circuits with a ground and added a ground to some existing 115 circuits.

I am removing s 230v stove and want a 115 socket there. I plan to take one 230 hot side and the 230 common for the new 115 socket. Then run a separate ground line to the plumbing under the kitchen sink. I might hook each hot to each receptacle on the new 115 socket, and break the tab. Your thoughts?
 
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Old 12-08-09, 11:23 AM
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I am removing s 230v stove and want a 115 socket there. I plan to take one 230 hot side and the 230 common for the new 115 socket. Then run a separate ground line to the plumbing under the kitchen sink. I might hook each hot to each receptacle on the new 115 socket, and break the tab. Your thoughts?
Not code compliant. You can not run a ground to a water pipe. It must go back to the breaker box. Best to just run #12 Romex.
 
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Old 12-08-09, 11:51 AM
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is pipe not safe to do? Why all the way to BB?
 
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Old 12-08-09, 01:09 PM
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The ground needs to be a low resistance back to the box. The main panel may not be bonded to the water pipe or at some point someone may repair the pipe with non-conductive pipe. I'm quoting NEC when I say back to the box. The NEC doesn't usually explain and can sometimes be ambiguous about the rules but it is best to follow them as best you can.
 
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Old 12-08-09, 01:23 PM
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Isn't the gnd wire just redundancy?
 
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Old 12-08-09, 04:18 PM
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Ray is correct that the grounding wire must go back to the panel where the circuit originates or to the grounding electrode conductor. It cannot go to the plumbing pipe.
 
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Old 12-08-09, 04:48 PM
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Originally Posted by paulmars View Post
Isn't the gnd wire just redundancy?
No. It is for safety to carry fault current so the breaker will open.
 
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Old 12-08-09, 05:09 PM
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Originally Posted by ray2047 View Post
No. It is for safety to carry fault current so the breaker will open.
gnd wire thru breaker?

"The message is too short. It must be at least 25 characters"

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Old 12-08-09, 05:26 PM
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Paul, the issue of equipment grounding is a long and complicated one, many professional electricians don't fully understand it. Entire books have been written on the subject.

I've posted this before and I really think it should be made a sticky. It is a 12-part series on grounding and bonding. Although written in a professional trade magazine it is understandable by lay persons if they try. I strongly urge you to read at least the first article.

Grounding versus Bonding.
 
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Old 12-08-09, 05:49 PM
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If there were to be a fault without a low impedance path back to the breaker, ie no ground, the breaker will continue to allow current to flow. This would allow parts that are not supposed to be energized to become energized.

Earth is a poor conductor of electricity so we provide a metallic path ie a conductor, to facilitate the breaker tripping.

The ground is not attached to the breaker
 
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Old 12-08-09, 06:42 PM
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tks furd and pcboss. That makes sense, but I still say a gnd wire is redundant.
 
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Old 12-08-09, 07:38 PM
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If you mean that in a perfect world electrical equipment will work just fine without the equipment ground wire I would have to agree with you in most cases.

The problem is that we don't live in a perfect world. I'd sure hate to be you if one of your loved ones (or even someone that you didn't care much for) lost their life because a piece of equipment had a fault but didn't trip the circuit breaker because there was not a low-impedance path for fault current.
 
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Old 12-08-09, 07:55 PM
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Originally Posted by furd View Post
...not a low-impedance path for fault current.
Neutral, if it fails, then ground is backup.

Im not minimizing the importance of a ground. Its important enough, to get a backup.
 
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Old 12-08-09, 08:01 PM
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No, NO, NO! the equipment ground is NOT a "back up" for the neutral. The equipment ground has one purpose and that is to provide the low impedance path back to the source that allows a high amperage current to flow which trips the circuit breaker or blows the fuse when there is a fault from the "hot" lead to the case of the equipment.
 
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Old 12-08-09, 08:16 PM
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Originally Posted by furd View Post
No, NO, NO! the equipment ground is NOT a "back up" for the neutral. The equipment ground has one purpose and that is to provide the low impedance path back to the source that allows a high amperage current to flow which trips the circuit breaker or blows the fuse when there is a fault from the "hot" lead to the case of the equipment.
Would not that happen via the neutral (w/ neutral to case) two wire system?
 
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Old 12-09-09, 05:12 AM
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Originally Posted by paulmars View Post
Would not that happen via the neutral (w/ neutral to case) two wire system?
If the case is connected to the neutral, then it only takes one failure to electrocute you. If the neutral wire opens up somewhere between that case and the service panel, then the next time you turn on that device, the case will be lethally hot.

But with a separate ground wire connected to the case, it takes two independent failures to electrocute you. One, is that the device in question would have to develop a short from hot to case; and two, the ground wire would have to open up between the case and the service panel.

The probability of two independent failures is much less than the single failure required in the first case.
 
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Old 12-09-09, 06:56 AM
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Originally Posted by BobInMichigan View Post
If the case is connected to the neutral, then it only takes one failure to electrocute you. If the neutral wire opens up somewhere between that case and the service panel, then the next time you turn on that device, the case will be lethally hot.

But with a separate ground wire connected to the case, it takes two independent failures to electrocute you. One, is that the device in question would have to develop a short from hot to case; and two, the ground wire would have to open up between the case and the service panel.

The probability of two independent failures is much less than the single failure required in the first case.
exactly. Its a backup. Its redundant. If the neutral fails, then the ground wire will be there. Everything on the LM moon landings and two backups, except for the lift off motor that is. Hmmmmm, I dont think I would have gone.

Next question, lets say my white neutral fails, so my appliance is operating using the ground wire. This could happen anywhere to anyone. How would we know, so we can fix it, before the appliance has a short and kills us?
 
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Old 12-09-09, 07:39 AM
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If the neutral fails the appliance will stop working. The return path for the current is not there and the circuit is not complete. The hot wire will still stay energized.

The neutral and grounds are for two different purposes.
 
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Old 12-09-09, 04:20 PM
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Originally Posted by pcboss View Post
If the neutral fails the appliance will stop working. The return path for the current is not there and the circuit is not complete. The hot wire will still stay energized.

The neutral and grounds are for two different purposes.
I am trying to wrap my mind around this...Neutral went to cabinet in two wire systems. If it failed and there was a short, the cabinet could be hot. Otherwise a short to cabinet would go back to box via the neutral and trigger the breaker.
 
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Old 12-09-09, 07:03 PM
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I'll try to help what has been said with some diagrams. I made long post to explain and possibly clarify and correct your misunderstandings but when I posted it something weird happened and the post was lost. I do not have time to redo it nor did i save it......


So some diagrams for you to study.

Things to understand

Neutral is never connected to metal likely to be energized load side of the service equipment .

Neutral is never connected to the equipment ground load side of the service equipment

The only exceptions to the above are old 3 wire range and dryer circuits where the metal chassis of the appliance was connected to the neutral terminal so that fault current could use the neutral of that branch circuit to return to the transformer. These 3 wire circuits were stopped in 1996 and 4 wire branch circuits with a equipment ground are now required.

Neutral is a current carrying wire and carries the same current that the hot wire does in 120 volt branch circuits. It is lethal if the right circumstances are in place.

The first diagram shows a fault to a metal receptacle box in a 2 wire with equipment ground 120 volt branch circuit.. The box is bonded to the equipment ground. Fault current uses the equipment ground and any bonded metal to return to the service panel and then uses the service neutral to return to the transformer. In other words this is called the 'effective ground fault path' and it provides for a low impedance path for fault current to complete the fault circuit with the transformer allowing a breaker to open. Notice there are no connections between the neutral and metal or equipment ground load side of the service equipment.


The next image is of a 120 volt branch circuit showing the normal completed circuit with the transformer with a load operating on that circuit. Notice the neutral and equipment ground are parallel but never connect till they get to the service panel. Also notice if I disconnect the neutral a the service panel the completed circuit is broken and all 120 volt loads operating will cease to work. The neutral also never connects to a metal box in a branch circuit. To connect them will allow neutral current to use the non current carrying equipment ground to return to the transformer . The equipment ground is never to be used to 'back up' the neutral to do so will turn the bare wire into a current carrying wire and will energize the metal and equipment ground. It will take another explanation later to discuss why this is dangerous. Maybe you will see why after studying these diagrams.



The next drawing shows what happens it we connect the non -current carrying equipment ground to the neutral of a 120 volt branch circuit. Remember the equipment ground system is for human safety so a breaker will open. It is not for carrying neutral current during normal operation of the dwellings electrical system. As you can see any metal that is likely to be energized in a ground fault is now permanently energized by the neutral and you are never going to know it. Very dangerous because the equipment ground is not expected to have current on it from the neutral.



This last last drawing is a 2 wire without ground. Notice if a hot wire touches the metal box there is no path available for fault current to use to return to the service equipment then out the service neutral to the transformer.

Remember current will seek the transformer and it will use any path to get there but it will take the lowest impedance path to get there if given more than one path and those other paths are very high in impedance. That is why it does not go to earth. And is also why we intentionally only construct one low impedance path to the transformer for neutral current and fault current to use...the common bridge is the service neutral.

 

Last edited by Bruto; 12-09-09 at 07:39 PM.
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Old 12-09-09, 07:18 PM
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The ground wire is used for saftey purposes and it should never conduct current. Current flowing through ground wire is bad. Neutral is used to complete the cricuit in a single phase system.
 
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Old 12-09-09, 07:56 PM
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Thanks. So, here is my revised plan. In my fuse box, the stove has two hots and a neutral. From my understanding this neutral is also a ground. Its connected to the common neutral bar in the box, common to all neutrals. However, no where does it connect to the metal box. I will pull one of the hots going to the stove and connect it to this bar in the box. So, at the box the neutral and ground will be common. Maybe I should connect it to the box and to earth too?

At the stove socket end, the wire I connected to the neutral bar I will use as the ground. I think this is where my confusion came from. At the socket I now have 3 wires. One hot, and two, neutral/ground wires. Either one could be connected to the 115v socket ground and the other to the socket neutral. Except for the color coding and that grounds usually have no insulation.
 
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Old 12-09-09, 10:04 PM
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I haven't totally read all of this thread so hopefully someone will
correct me if I am mistaken. You want to take a 3 wire 240 volt stove branch circuit and convert it to 120 volts and install a receptacle.

Before reading on would by chance these 3 wires for this stove be inside a metal raceway like emt or armored cable....?? If so you have a good chance of having a ground by using the conduit. If not read on...


Some problems you may encounter...

The new breaker (probably a 20 amp single pole) will likely not accept the bigger wire of a stove/ range branch circuit if it is #8 or #6 so you would have to reduce wire size to fit the breaker this will require pigtails of 12 awg copper if you use a 20 amp breaker... which you should...and wire connectors. Same at the other end in order to terminate on the receptacle(s).

You do not have a properly identified equipment ground but your plan to use a hot as an equipment ground, the white as a neutral and the other hot preferable the black one as your hot wire is better than the first plan. Move one hot to the neutral bus along with the white, which is already there. And attach the black to a single pole breaker probably 20 amp.

This is a much better plan than the ground to the water pipe...

You have one minor code violation and that is remarking a wire that is 6 awg or smaller as a ground that is carrying a hot conductor insulation color. . Just be sure you remark the hot wire you use as equipment ground by taping it green everywhere it is exposed to sight. I would correct this whole installation if you sell the house and be darn sure if someone is working in the panel or at the receptacle they are aware of your changes.

The installation is not the best and sorta convoluted but I believe your going to do this no matter what we say.... so I give you my blessings...
 
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Old 12-10-09, 12:35 AM
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Maybe I should connect it to the box and to earth too?
No not necessary just connect it to the terminal bar.


At the stove socket end, the wire I connected to the neutral bar I will use as the ground. I think this is where my confusion came from. At the socket I now have 3 wires. One hot, and two, neutral/ground wires. Either one could be connected to the 115v socket ground and the other to the socket neutral. Except for the color coding and that grounds usually have no insulation.


I wish you would stop combining the neutral and ground in your terminology. It's either a neutral or a ground but I understand what your saying..... Yes you could connect either one to socket neutral but there is only one way that is correct.... The electricity only sees a wire....
 
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Old 12-10-09, 01:37 AM
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Actually Bruto, now I am considering running a new line. Let me ponder this for awhile...Done.

I will use the existing 230 line as detailed below. Its a fuse box, so the hots are attached to the fuse housings. Just need to change the 35a to 20a and of course move the other hot to gnd. Green tape?

How many 20a socket boxes can i attach to a 20a line? I might attach two/three in such a way, that it will be easy to bring in a new circuit line thru the wall later. I will need to do that when and if the stove is ever needed again. But for now, I save a trip into the attic.
 
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Old 12-10-09, 01:42 AM
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Originally Posted by Bruto View Post
...It's either a neutral or a ground ...
yes, depending on if I hook it to the socket's neutral screw or to the gnd screw.
 
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Old 12-10-09, 01:50 AM
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Originally Posted by paulmars View Post
yes, depending on if I hook it to the socket's neutral screw or to the gnd screw.
Im not trying to be a smart a**. I cant help but think of these two wires as the same. Since electrically, they are. Both provide a "return" source. I understand, that how they are used at the appliance end is totally different.
 
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Old 12-10-09, 05:08 AM
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The insulated wire you removed from the fuseholder should become the neutral. You do not want the uninsulated wire carrying current.
 
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Old 12-10-09, 08:17 AM
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Originally Posted by pcboss View Post
The insulated wire you removed from the fuseholder should become the neutral. You do not want the uninsulated wire carrying current.
I thought all 3 wires were insultated? But if one is bare then absolutely that is the one you want to use for ground.
 
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Old 12-10-09, 08:22 AM
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Originally Posted by paulmars View Post
Im not trying to be a smart a**. I cant help but think of these two wires as the same. Since electrically, they are. Both provide a "return" source. I understand, that how they are used at the appliance end is totally different.
Yeah I know what you mean to say. They are both grounded wires but one carries system current and one doesn't. Sorry I gave you a hard time just trying add a bit of humor.

I missed that one of the wires was uninsulated? but as PCBOSS said that would be the one you want to use for equipment ground.

Your plans though keep getting better.... A new line is the best way to go...
 
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Old 12-10-09, 09:35 AM
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Originally Posted by pcboss View Post
The insulated wire you removed from the fuseholder should become the neutral. You do not want the uninsulated wire carrying current.
From what I understand, at the box I will leave the neutral and one power (hot) wire as is. I will remove the other hot wire from the fuse holder and connect it to the neutral bar. At the socket end I will find out which is hot (they are both black insulation) and I will then use the other black insulated as the neutral(common) and the previous uninsulated neutral, as the ground. Did I say that right?
 
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Old 12-10-09, 09:51 AM
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How many socket boxes can I attach to a 20a circuit? Is green tape a code thing, or can i use anything to mark the old hot that will be neutral?
 
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Old 12-10-09, 11:51 AM
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Originally Posted by paulmars View Post
From what I understand, at the box I will leave the neutral and one power (hot) wire as is. I will remove the other hot wire from the fuse holder and connect it to the neutral bar. At the socket end I will find out which is hot (they are both black insulation) and I will then use the other black insulated as the neutral(common) and the previous uninsulated neutral, as the ground. Did I say that right?
Yes that is correct you should identify the black/neutral with some white tape wrapped around it... just to be a little better understood if someone comes behind you. The bare you can leave as is...

I said green tape earlier because I thought you had all insulated wires and none were bare. I also assumed one of them was a white neutral so you would have been taping a black wire green for ground. MY mistake.

I apologize for missing the uninsulatd wire ... I never did see where you said but I should have realized that most older installs were done with se type wire with a bare neutral.

Personally I would abandon this idea/plan ........it's just to goofy...
 
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Old 12-10-09, 12:00 PM
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Originally Posted by paulmars View Post
How many socket boxes can I attach to a 20a circuit? Is green tape a code thing, or can i use anything to mark the old hot that will be neutral?
The green tape is not necessary I misunderstood what you had as all insulated wires. White tape the hot wire you move to the neutral bar to use as the neutral. Leave the bare alone.

think about not doing this.....

How many receptacles do you want and are you talking about the new line or this other one that is existing..??
 
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Old 12-10-09, 12:02 PM
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Originally Posted by Bruto View Post
I apologize for missing the uninsulatd wire ... I never did see where you said but I should have realized that most older installs were done with se type wire with a bare neutral.

Personally I would abandon this idea/plan ........it's just to goofy...
1-I never did originally say it was uninsulated, although it is.

2-Why is it goofy? Effectively all I m doing is using a heavier gauge then required and using black for neutral.

3-How many socket boxes in kitchen can go on one 20a circuit. What the code say?
 
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Old 12-10-09, 12:10 PM
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Originally Posted by paulmars View Post
1-I never did originally say it was uninsulated, although it is.

2-Why is it goofy? Effectively all I m doing is using a heavier gauge then required and using black for neutral.

3-How many socket boxes in kitchen can go on one 20a circuit. What the code say?
Ok maybe goofy was not the right word...do it right and identify the neutral with white tape and I'll be happy...

As for receptacles/sockets the general rule is not more than 12 for a 20 amps circuit but the code really doesn't care how many they expect you to use common sense though in what you plug into them...
 
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Old 12-10-09, 12:14 PM
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ok, thanks. I install three sockets
 
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Old 12-10-09, 12:23 PM
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Originally Posted by paulmars View Post
ok, thanks. I install three sockets
If any are up on the countertop they should be gfci.
 
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Old 12-10-09, 12:49 PM
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Originally Posted by Bruto View Post
If any are up on the countertop they should be gfci.
Done

(The message you entered is too short. It must be at least 25 characters) Happy now mr code?
 
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Old 12-10-09, 12:55 PM
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Not to confuse but if you are going to have this inspected the NEC does not allow wires #6 or smaller to be re-identified except in special circumstances. This is not one of those so you might want to check with the AHJ if your going to have it inspected.
 
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