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Old 08-19-2011, 10:44 PM   #1
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Iso ground circuit on GFI breaker


I'm wiring a subpanel for an addition. Last circuit is a dedicated washing machine circuit, planning to use GFCI breaker which I know is a controversial topic. The receptacle is an iso ground for some reason, which means 3 wire going to the GFI breaker. How to connect it? Instructions for iso ground have the red wire marked green and going to neutral or ground bus, white going to neutral, but that leaves the neutral terminal on the breaker empty?

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Old 08-19-2011, 10:55 PM   #2
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Iso ground circuit on GFI breaker


Black (or 'hot' wire) and white from the circuit go to the breaker. White from the breaker goes to the panel neutral bar. Ground(s) from the circuit go to the ground bar. You mention this is a sub-panel, so the ground bar and the neutral bar in the panel must be kept separate. Why is it an isolated ground receptacle?

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Old 08-19-2011, 11:12 PM   #3
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Iso ground circuit on GFI breaker


Don't know why it's an iso ground receptacle. Any reason at ALL to have a washer on one? If not, what to do with the extra red wire? Can't easily run a new 2-wire now.
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Old 08-19-2011, 11:34 PM   #4
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Iso ground circuit on GFI breaker


No reason to have an iso for laundry that I know of. Cap off the red at both ends, and ground the recpt as normal, and the recpt box if it’s metal. Consider changing the iso to a regular recpt to avoid confusion later.
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Old 08-19-2011, 11:41 PM   #5
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Iso ground circuit on GFI breaker


Great, thanks a bunch for the help. You think keep a regular outlet on the GFI breaker, or not at all necessary? I figure GFI protection somewhere isn't a bad idea; washer has potential for water leaks very near the outlet.
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Old 08-19-2011, 11:51 PM   #6
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Iso ground circuit on GFI breaker


If the laundry recept is in an unfinished basement, it requires GFCI protection (breaker or GFI recpt…either is fine). If the laundry is in a finished area, only requires GFI if within 6’ of a sink. I’d get rid of the iso recpt though.
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Old 08-19-2011, 11:52 PM   #7
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Iso ground circuit on GFI breaker


You mention that the isolated ground is currently connected to a red wire. Presumably this is because the installer used normal 12-3 wire, re-purposing the red wire as the second ground. This is illegal and dangerous. A grounding conductor MUST be bare, green, or green with a yellow stripe. Isolated ground traditionally uses green with a yellow stripe. It is dangerously easy for someone to accidentally connect the red wire to a power source, since that is the normal use of that color conductor. Since you don't need isolated ground anyway, you should disconnect the red conductor at both ends and use a standard receptacle.
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Old 08-20-2011, 06:24 AM   #8
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Iso ground circuit on GFI breaker


Quote:
Originally Posted by ironnickwhite View Post
I'm wiring a subpanel for an addition. Last circuit is a dedicated washing machine circuit, planning to use GFCI breaker which I know is a controversial topic. The receptacle is an iso ground for some reason, which means 3 wire going to the GFI breaker. How to connect it? Instructions for iso ground have the red wire marked green and going to neutral or ground bus, white going to neutral, but that leaves the neutral terminal on the breaker empty?
That is the confusing part.

Remember, Green...or ground is a safety issue......in a perfect world, there would be no current to ground.....

To expand on the sub panel issue.....you will notice that you do NOT tie earth ground to the neutral buss inside the sub panel. Your neutral is tied to ground in ONE place....main load center.

When I did my garage with it's sub panel...I had to add an additional ground rod (actually 2) at the garage. Those ground rods go to the sub panel. I also have a ground coming from my main panel to my sub...but I did NOT tie the ground to neutral.

I personally have issues with taping a red wire white. I see no reason for it unless someone is trying to take short cuts. Tape tends to fall off over time. Nothing worse than working on a system where wire color is not followed. If I see a black wire...I expect it to be HOT.....not something else. (unless we are talking DC...then it's ground....go figure)

One last thing....Isolated ground? Why? I could see that if you were running an expensive audio system....but a washer and dryer? That should be the same ground as everthing else.

Rule of thumb....if something is sitting on concrete...it needs a GFIC. Concrete is an excelent ground...so good that the standard code for new construction is to use the rebar (UFER) as your earth ground. I'm doing a 2-story addition to my house right now....not only do I have ground rods...but I'm also tied into my foundation via the rebar.

I think I'll make some resistance measurements tomorrow to see how good my ground is.....I suspect it's going to be VERY good.
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Old 08-20-2011, 08:15 AM   #9
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Iso ground circuit on GFI breaker


Sounds like you are using one of those DIY wiring books. I know there is one of them that shows using a red wire for the ground. That is wrong.
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Old 08-20-2011, 10:06 AM   #10
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Iso ground circuit on GFI breaker


The red wire can stay capped off for future use. It could be used if another, 120 volt, circuit is daisy chained from the washing machine outlet box using said red wire and sharing the neutral (multiwire branch circuit).
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Old 08-20-2011, 11:35 AM   #11
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Iso ground circuit on GFI breaker


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Sounds like you are using one of those DIY wiring books. I know there is one of them that shows using a red wire for the ground. That is wrong.
The Black & Decker Complete Home wiring guide shows the red on the romex taped with green tape on both ends, the green or ground to the junction box. This is what the notation states "16. Dedicated 120-volt Computer Circuit, Isolated-ground Receptacle. This 15-amp isolated-ground circuit provides extra protection against surges and interference that can harm electronics. It uses 14/3 cable with the red wire serving as an extra grounding conductor. The red wire is tagged with green tape for id. It is connected to the grounding screw on an "isolated-ground" receptacle and runs back to the grounding bus bar in the circuit breaker panel without touching any other house wiring."

Now of course, yes that is wrong. The only place that I have a iso ground receptacle, is downstairs, and it is in a jb attached to the side of my breaker panel, for the electronics plugged in for the network gear down there. Of course, wired per code with the box being the isolated ground, green #14 to the ground screw, white & black wired accordingly. I would not use a iso ground on a washing machine, because that would not be what they are intended for.

Last edited by gregzoll; 08-20-2011 at 11:38 AM.
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Old 08-20-2011, 07:23 PM   #12
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Iso ground circuit on GFI breaker


Just for info if you only have one receptacle on the circuit you have an isolated ground by default.
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Old 08-20-2011, 07:49 PM   #13
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Iso ground circuit on GFI breaker


Quote:
Originally Posted by ddawg16 View Post
That is the confusing part.
I'm doing a 2-story addition to my house right now....not only do I have ground rods...but I'm also tied into my foundation via the rebar.

I think I'll make some resistance measurements tomorrow to see how good my ground is.....I suspect it's going to be VERY good.
What type of meter are you using?
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Old 08-20-2011, 07:53 PM   #14
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Iso ground circuit on GFI breaker


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Just for info if you only have one receptacle on the circuit you have an isolated ground by default.
Actually no. A single receptacle can still have a ground loop problem.
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Old 08-20-2011, 08:21 PM   #15
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Iso ground circuit on GFI breaker


Quote:
Originally Posted by ddawg16
If I see a black wire...I expect it to be HOT.....not something else. (unless we are talking DC...then it's ground....go figure)
I didn't know that DC circuits were grounded.

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