Help! I'm and idiot. I fed receptacles on A, B & C phase branch circuits sharing a common neutral. These circuits are fed by GFCI breakers. I jumped the neutral between the breakers and the breakers are tripping. I should have run a seperate neutral with each phase to terminate at the GFCI breakers. DOES ANYBODY KNOW A WIRING TRICK TO FAKE OUT THESE BREAKERS AND STILL PROVIDE GFCI PROTECTION?
GFCI circuit breakers
- Thread starter temecwil
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luke warmwater
Senior Member
Re: GFCI circuit breakers
The answer to your question is No.
Option #1: (least favorite) ;
Pull in another grounded conductor and use (1) 1-pole GFCI breaker and (1) 2-pole GFCI breaker.
(Again, not recommended)
Option #2: (your option)
" I should have run a seperate neutral with each phase to terminate at the GFCI breakers."
Option #3: (probably easiest, quickest, cheapest) ;
Replace (3) 1-pole GFCI breakers with standard 1-pole breakers and use GFCI receptacles. Tail neutral on line side.
The answer to your question is No.
Option #1: (least favorite) ;
Pull in another grounded conductor and use (1) 1-pole GFCI breaker and (1) 2-pole GFCI breaker.
(Again, not recommended)
Option #2: (your option)
" I should have run a seperate neutral with each phase to terminate at the GFCI breakers."
Option #3: (probably easiest, quickest, cheapest) ;
Replace (3) 1-pole GFCI breakers with standard 1-pole breakers and use GFCI receptacles. Tail neutral on line side.
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: GFCI circuit breakers
I have found from both this forum and fellow electricians that many are confused about how gfci works.Perhaps someone can post the diagram.I suggest they break open an old or defective one to see the electronics in them.Many look at you funny when you tell them that the ground wire has nothing to do with it working.
I have found from both this forum and fellow electricians that many are confused about how gfci works.Perhaps someone can post the diagram.I suggest they break open an old or defective one to see the electronics in them.Many look at you funny when you tell them that the ground wire has nothing to do with it working.
B
bthielen
Guest
Re: GFCI circuit breakers
The easiest way for me is to remember that any and all current found on the ungrounded conductor must also be equally found on the grounded conductor. Any difference of current between the two and the GFCI will trip. When sharing neutral with multiple branch circuits, the neutral current can obviously be different than the current on any one of the ungrounded conductors. This will trigger a GFCI fault.
Bob
The easiest way for me is to remember that any and all current found on the ungrounded conductor must also be equally found on the grounded conductor. Any difference of current between the two and the GFCI will trip. When sharing neutral with multiple branch circuits, the neutral current can obviously be different than the current on any one of the ungrounded conductors. This will trigger a GFCI fault.
Bob
luke warmwater
Senior Member
Re: GFCI circuit breakers
tshea,
see my Option #3 in my earlier post.
tshea,
see my Option #3 in my earlier post.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: GFCI circuit breakers
I believe this is what Luke was referring to.
Maybe Ed will post a diagram to make this more clear?
What would we do without Ed?
[ March 04, 2005, 06:39 PM: Message edited by: hurk27 ]
Yes at the first point where the two legs split up and no longer share the neutral as they go there own ways. We do this all the time to cut down on home runs in a large house. If you split fed the receptacles ( this is where you would have broke the tabs on the receptacles to have each side of the receptacle on its own circuit) then you will have to do some wiring to separate them to allow each receptacle to have it's own neutral from the point the multiwire splits up. but once you make your run from the multi-wire split to the first receptacle (GFCI) you can not use any shared neutral after this point.
I believe this is what Luke was referring to.
Maybe Ed will post a diagram to make this more clear?
What would we do without Ed?
[ March 04, 2005, 06:39 PM: Message edited by: hurk27 ]
Re: GFCI circuit breakers
Imagine a donut shaped transformer (commonly called toroid and used as Current Tranformer abbrieviated CT) with the phase wire and the neutral wires looped several times through the center. Now attach the wires from the CT to an Ammeter. When current flows in the phase wire an equal amount of current will flow in the opposite direction in the neutral wire (wheather the neutral on the XFR is grounded or not, and you could use all the ungrounded wires feeding a 208 or 240 load) As long as all the currents flowing in the phase and or neutral wires algabraiclly sum to zero there will be no current flowing in the CT and the ammeter will read zero. However if the current in any leg of the power circuit does not carry it's share of the circuit current current will flow in the CT circuit and the ammeter will read the current.
The amount of current flowing in the CT circuit will be directly proportional to the amount of unbalance in the power (primary) circuit multiplied by the number of times the primary wires loop the CT. With the proper calculations an electronic relay could replace the ammeter that would trip the primary circuit when the current in the CT (secondary) circuit reached the fault level, (in GFI devices for 120V circuits this is micro amps)
I have a drawing in Power point but i dont know how to paste it in.
Imagine a donut shaped transformer (commonly called toroid and used as Current Tranformer abbrieviated CT) with the phase wire and the neutral wires looped several times through the center. Now attach the wires from the CT to an Ammeter. When current flows in the phase wire an equal amount of current will flow in the opposite direction in the neutral wire (wheather the neutral on the XFR is grounded or not, and you could use all the ungrounded wires feeding a 208 or 240 load) As long as all the currents flowing in the phase and or neutral wires algabraiclly sum to zero there will be no current flowing in the CT and the ammeter will read zero. However if the current in any leg of the power circuit does not carry it's share of the circuit current current will flow in the CT circuit and the ammeter will read the current.
The amount of current flowing in the CT circuit will be directly proportional to the amount of unbalance in the power (primary) circuit multiplied by the number of times the primary wires loop the CT. With the proper calculations an electronic relay could replace the ammeter that would trip the primary circuit when the current in the CT (secondary) circuit reached the fault level, (in GFI devices for 120V circuits this is micro amps)
I have a drawing in Power point but i dont know how to paste it in.
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
- Status