Gfci in subpanel without neutral feed


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Old 12-11-13, 07:40 AM
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Gfci in subpanel without neutral feed

Will a gfci operate correctly in a 240v only subpanel fed by 10/2 with ground but no neutral? It seems I have read that the breaker needs the 120v feed it gets from the neutral in order for the internal electronics to operate. Thanks.
 
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Old 12-11-13, 09:00 AM
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Welcome to the forums!

When you ask about
a 240v only subpanel fed by 10/2 with ground but no neutral
are you actually asking about a disconnect? How many loads are fed from this enclosure?

To answer your question, for a 240V only circuit, the neutral pigtail on the 2-pole 240V GFCI breaker isn't used.

Here's an earlier thread on this topic that may be relevant: 2 Pole 60 Amp GFCI Subpanel for hot tub question....
 

Last edited by ray2047; 12-11-13 at 09:51 AM. Reason: 340>240
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Old 12-11-13, 10:00 AM
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I may have been wrong in the link Nash referenced. From the Mike Holt forum:
Two pole GFI breakers require a line side neutral (in order for the breaker electronics to work). Load with, or without, neutrals may be connected to the load side of the GFI breaker. 240v GFCI work with no neutral ??
 
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Old 12-11-13, 10:09 AM
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Originally Posted by ray2047
I may have been wrong in the link Nash referenced.
Oops! First time for everything.

Tony, what are you trying to protect, and what is your current setup?
 
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Old 12-11-13, 10:38 AM
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In a separate thread I posed the question of whether or not I could place a subpanel fed by an existing 10/2 with ground cable. This line ( 150 ft) currently feeds an irrigation pump from my house panel (30a breaker). I want to put a sub panel near pump location to feed the pump as well as a new two motor boat lift, some 125 feet or so from proposed subpanel. The feed to the boat lift will go underwater prior to where the control switches for the lift will be. Obviously I have to have gfci protection, so I figured it best located at the start of this run (subpanel), before any of the wire enters the water. I could put the gfci in the house main but after reading it seems nuisance trips are an issue at my distances.

Initially I figured on a 12a load from the lift, which was probably ok with my run using 10. However, the motors are actually going to be around a 15a load instead, and call for 8 guage at my run length. Can I switch to a larger wire at the subpanel to overcome any voltage drop issues?

If I do that will I have to increase the size of the breaker in the subpanel to accommodate the larger wire. Ultimately I would start with 30a breaker in main with 10/2 going to a 40 or 50A breaker in subpanel, upon witch switching to 6 or 8 wire to my load. Is that even remotely acceptable?
 
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Old 12-11-13, 01:47 PM
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Ordinarly there is no useful purpose using 50 mp breakers an/or #8 or #6 wire at the subpanel fed by #10 gauge wire from the main house. Just overkill.

But if the continuation from the subpanel to the load is long, heavier wire could be used to cut down on extra voltage drop over and above that suffered in the line from the main house. Unlike with plumbing, heavier wire for the second half of a run is not rendered useless for voltage drop purposes because of lighter wire for the first half of the run. Each section of wire in the circuit contributes the same amount of voltage drop depending on amperes flowing regardless of the order in which the wires are connected.

And a larger amperage breaker might be a workaround if a 30 amp breaker won't physically accept the #8 wire. The disadvantage here is that if you actually trip a breaker, it will be the breaker up in the main house and you would have to walk over there to reset it.
 
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Old 12-11-13, 03:11 PM
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So is the consensus that a gfci breaker will not work in this panel until I get a new feed to it with a neutral? Are there any gfci options for me under these circumstances? I know the motor cords have inline gfci's that I was going to remove, would they provide and option? What about receptacles at the lift? Thanks for the help everyone.
 
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Old 12-11-13, 06:31 PM
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So is the consensus that a gfci breaker will not work in this panel until I get a new feed to it with a neutral?
Yes

Are there any gfci options for me under these circumstances?
You could use a 2 pole GFI breaker if you can operate the lifts on 240 volts.

I know the motor cords have inline gfci's that I was going to remove, would they provide and option? What about receptacles at the lift?
If the cords are intended to be hardwired you will need the inline GFCI devices. If the cords have plugs on them and intended to be plugged in I think the inline GFCIs should be removed. Any 120 volt receptacle you install on the dock whether for a boatlift or not needs to be GFCI protected.
 
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Old 12-11-13, 07:06 PM
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This whole circuit will be 240 all the way, so I am still not certain if can place a gfci breaker in the panel given I have no line side neutral for the pigtail to connect to.

Should I just go ahead and give in and put in a new 4 wire feed?
 
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Old 12-11-13, 07:43 PM
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Should I just go ahead and give in and put in a new 4 wire feed?
Sure. That'll bring it up to current code and enable the GFCI protection at the same time.
 
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Old 12-12-13, 05:55 AM
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This whole circuit will be 240 all the way, so I am still not certain if can place a gfci breaker in the panel given I have no line side neutral for the pigtail to connect to.
You could use a 2 pole GFCI breaker on a 240 volt only circuit, not a single pole GFCI breaker

Should I just go ahead and give in and put in a new 4 wire feed?
Yes, I agree with Nash on this.
 
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Old 12-13-13, 03:15 PM
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Concerning the new feed to the subpanel, I have available for free plenty of aluminum triplex 4-4-4. I am not sure what the rating is at this time. Are there types of triplex that I could run in conduit from my crawl space to my subpanel? Can you add a single conducter to combine for a 4 wire feed? If not then I will just pass on the triplex.
 
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Old 12-13-13, 04:13 PM
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Concerning the new feed to the subpanel, I have available for free plenty of aluminum triplex 4-4-4.
#4 aluminum is good for 65 amps, you could protect it with a 60 amp breaker. Triplex is a term that usually refers to an overhead drop with two insulated and one bare neutral conductor or direct burial with two black conductors and one yellow (or black with yellow tracer) neutral conductor. I suspect what you are referring to is the direct burial triplex, but you need 4 conductors. You could add the 4th direct burial (ground) conductor, a #8 aluminum or #10 copper if you use Type USE wire. I wouldn't recommend trying to pull direct burial triplex into conduit. If you really want to use conduit you don't need triplex, just use aluminum Type XHHW conductors.

Free is a strong inducement. I believe what I'd do is run the free #4 aluminum triplex direct buried and throw a #8 aluminum Type USE ground conductor in the ditch (doesn't have to be green). Install a conduit sleeve at each end where the wire emerges from the ditch.
 
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Old 12-14-13, 07:20 AM
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I have confirmed that it is USE-2. This means I can take it inside my house to my main panel, correct?

Are you sure that i can use a black ground if it is #6 or smaller? I thought I read that black could be used only if it was bigger than #6.
 
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Old 12-14-13, 01:32 PM
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I have confirmed that it is USE-2. This means I can take it inside my house to my main panel, correct?
No

USE cannot be used above ground except where it emerges from ground and terminates in an enclosure at an outdoor location.
Are you sure that i can use a black ground if it is #6 or smaller? I thought I read that black could be used only if it was bigger than #6.
I don't believe a #8 has to be green in this situation, but I'll look into it and see for sure.

I was wrong, a #8 must be green or green with one or more yellow stripes.

When you install a No. 6 or smaller EGC, the insulation along its entire length must be colored green or green with one or more yellow stripes. You can also use a completely bare EGC under certain conditions. If the job calls for an EGC that's larger than No. 6 copper or aluminum, it must be color-coded at each end and at every point where the conductor is accessible.
Behind the Equipment Grounding Conductor | Code Basics content from Electrical Construction & Maintenance (EC&M) Magazine
 

Last edited by CasualJoe; 12-14-13 at 03:11 PM.
 

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