The plans I have call for a 3 wire(2 hots, 1 grnd)208V receptacle located on the outside wall of the bldg. The plans also call for this recep. to be GFI protected. Can I use a 2 Pole GFI Breaker even though there is no nuetral run to the recep? If yes how does it work and where do I take the white conductor on the breaker? The only thing that makes any sense is to take the white wire to ground in the panel????? I wanna know for sure and why! thanks, justin
2 Pole GFCI Breaker?
- Thread starter justin
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- Bremerton, Washington
Re: 2 Pole GFCI Breaker?
A GFCI does not require a neutral to operate. it measures the leakage to ground. There may be a neutral wire with the CB in case a multiwire ciruit is used. I don't know if the internal circuitry in a 208 V GFCI CB operates at 120 and requires the neutral for its internal circuitry, I would not think so.
What is the amperage of the receptacle?
A GFCI does not require a neutral to operate. it measures the leakage to ground. There may be a neutral wire with the CB in case a multiwire ciruit is used. I don't know if the internal circuitry in a 208 V GFCI CB operates at 120 and requires the neutral for its internal circuitry, I would not think so.
What is the amperage of the receptacle?
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: 2 Pole GFCI Breaker?
Justin connect the neutral to the neutral bar it does need this connection for the test button on the breaker to function. But do not connect the ground wire to the neutral connection on the breaker connect it to the ground bar. as connecting it to the neutral on the breaker will allow full current to flow on the grounding without the breaker tripping. there is no need for a connection to the neutral on the breaker if there is not going to be any 120 volt load. the way a GFCI works is by comparing current in the two hot conductors (and neutral if used). It does this by running all the conductors through a current coil or transformer if the current is balanced on all the conductors there will be no current induced into the coil and everything is hunky dorey. but if current happens to flow through somthing else, metal framing, your body someone else body, Etc... then the current in the conductors would be no longer balanced and current will begin to flow in the coil. When the level goes high enough (5ma.) the electronics will trip the breaker and remove the power from the circuit. thus protecting whom ever decided to become a path for the return current. This is the bases of all GFCI, GFP, and part of the circuitry in a AFCI that allows them to function.
Hope this broadens your understanding of how they work.
Wayne
[ October 29, 2003, 01:38 AM: Message edited by: hurk27 ]
Justin connect the neutral to the neutral bar it does need this connection for the test button on the breaker to function. But do not connect the ground wire to the neutral connection on the breaker connect it to the ground bar. as connecting it to the neutral on the breaker will allow full current to flow on the grounding without the breaker tripping. there is no need for a connection to the neutral on the breaker if there is not going to be any 120 volt load. the way a GFCI works is by comparing current in the two hot conductors (and neutral if used). It does this by running all the conductors through a current coil or transformer if the current is balanced on all the conductors there will be no current induced into the coil and everything is hunky dorey. but if current happens to flow through somthing else, metal framing, your body someone else body, Etc... then the current in the conductors would be no longer balanced and current will begin to flow in the coil. When the level goes high enough (5ma.) the electronics will trip the breaker and remove the power from the circuit. thus protecting whom ever decided to become a path for the return current. This is the bases of all GFCI, GFP, and part of the circuitry in a AFCI that allows them to function.
Hope this broadens your understanding of how they work.
Wayne
[ October 29, 2003, 01:38 AM: Message edited by: hurk27 ]
pierre
Senior Member
- Location
- Westchester County, New York
Re: 2 Pole GFCI Breaker?
I am not positive, but is not the white (neutral) conductor that is connected to the 2 pole GFCI breaker necessary for the breaker circuitry to operate properly. I say that this info should be researched and a proper answer posted, before the answer is read by many who may not fully understand it themselves.
Pierre
I am not positive, but is not the white (neutral) conductor that is connected to the 2 pole GFCI breaker necessary for the breaker circuitry to operate properly. I say that this info should be researched and a proper answer posted, before the answer is read by many who may not fully understand it themselves.
Pierre
Re: 2 Pole GFCI Breaker?
Called Square D, up to 50A, GFCI, it has a pigtail for the neutral. This does not need to be connected out to the load if it is straight 208/240V. However, a ground connection is required, and a wire is recommended, not just conduit. Recommend you check the literature that comes with the device installed.
Called Square D, up to 50A, GFCI, it has a pigtail for the neutral. This does not need to be connected out to the load if it is straight 208/240V. However, a ground connection is required, and a wire is recommended, not just conduit. Recommend you check the literature that comes with the device installed.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: 2 Pole GFCI Breaker?
Pierre
Also this is the same when we use a receptacle type GFCI without a grounding conductor. in this case since there is a neutral connected the test button will still work on the receptacle, but if you use a pluge in tester the test button on the plug in tester will not function as it also uses ground to trip the GFCI circuitry. the test button on the receptacle places a resistor around the current coil to the neutral to cause an unbalance in the circuit.
[ October 29, 2003, 07:34 PM: Message edited by: hurk27 ]
Pierre
The neutral pigtail is not for the operation of the breaker as the GFCI circuit does not need a referance to ground. if there was 120 volts being used then yes as the neutral would have to be connected to provide a monitored neutral return path. but for just 240 volts it would still operate just fine. But the test button on the breaker would not work. the test button places a resistor to this neutral to trip the circuitry. The two ungrounded conductors will still be monitored through the current coil and the breaker would still funtion. Remember the GFCI circuitry just need equal current on the wires that are going through the current coil if one has more current on it than the other the breaker will trip. and this is also true if the neutral is being used as it also passes through the coil. but when it is not used then there is no current on the neutral to cause current in the coil.
Also this is the same when we use a receptacle type GFCI without a grounding conductor. in this case since there is a neutral connected the test button will still work on the receptacle, but if you use a pluge in tester the test button on the plug in tester will not function as it also uses ground to trip the GFCI circuitry. the test button on the receptacle places a resistor around the current coil to the neutral to cause an unbalance in the circuit.
[ October 29, 2003, 07:34 PM: Message edited by: hurk27 ]
strmtrpr73
Member
Re: 2 Pole GFCI Breaker?
I have a similar question. I have a spa heater 240 V system (2hots and ground). I was told that the ground wire for this circuit should be connected to the load neutral lug on the breaker, and connect the neutral pig tail to the ground bar(not the neutral bar). I was curious how this was supposed to work. SO I tried it. And what do you think happened. The breaker tripped. I was told to do this to protect the ground wire (from what I never know). I thought about it all night before I tried it, I didn't think it would work. I think I know why it tripped but I am not sure. The equipment ground for the heater has a continuity reading from it to the ground bar,( because of the spa bounding wire). Is it possible the internal circuitry of the breaker was sensing something wrong with this. I hooked the breaker up The way I thought it should go: neutral pigtail to the neutral bar, ground to the ground bar. And it worked just fine, I believe that it will still protect. Am I correct in my thinking.
I have a similar question. I have a spa heater 240 V system (2hots and ground). I was told that the ground wire for this circuit should be connected to the load neutral lug on the breaker, and connect the neutral pig tail to the ground bar(not the neutral bar). I was curious how this was supposed to work. SO I tried it. And what do you think happened. The breaker tripped. I was told to do this to protect the ground wire (from what I never know). I thought about it all night before I tried it, I didn't think it would work. I think I know why it tripped but I am not sure. The equipment ground for the heater has a continuity reading from it to the ground bar,( because of the spa bounding wire). Is it possible the internal circuitry of the breaker was sensing something wrong with this. I hooked the breaker up The way I thought it should go: neutral pigtail to the neutral bar, ground to the ground bar. And it worked just fine, I believe that it will still protect. Am I correct in my thinking.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: 2 Pole GFCI Breaker?
strmtrpr73
[ November 09, 2003, 03:52 AM: Message edited by: hurk27 ]
strmtrpr73
This is exactly why it triped as the bonding of the heater to the waterlines provided a path for return current to flow. this caused a voltage to be produced in the current coil that caused the breaker to open. This could of also allowed full currnet on the grounding as it defeated the GFCI circuit as this ground wire would now allow full load current on it as all three conductors are now passing through the current coil. Of course this would only happened if the proper bonding wasn't done. Not in your case. but it could of been a setup for someone to get shocked. as the GFCI breaker would treat the ground like a neutral. Glad you caught it.
[ November 09, 2003, 03:52 AM: Message edited by: hurk27 ]
Re: 2 Pole GFCI Breaker?
Let's think about this... It looks as if all agree that no load side neutral is required as there is no neutral for the load anyway.
However, the line side white pigtail neutral is important to connect to a neutral even though there is no neutral load. If the brains of the GFCI were to be powered by the L-L connection, that is if it was its sole source of power, then if one of the lines feeding the breaker were lost the GFCI sensing would be defeated. There would be a line to ground shock potential between the energized load side line and ground , that is it GFCI would not operate.
With the white pigtail tied to the line side neutral if either line were to be open the GFCI would still operate.
However, for the GFCI to be able to provide GFCI protection with one line open and the neutral pigtail not connected to a line side neutral, a line to ground current from the energized line to ground must be sufficient to power the GFCI brains to trip the breaker.
Let's think about this... It looks as if all agree that no load side neutral is required as there is no neutral for the load anyway.
However, the line side white pigtail neutral is important to connect to a neutral even though there is no neutral load. If the brains of the GFCI were to be powered by the L-L connection, that is if it was its sole source of power, then if one of the lines feeding the breaker were lost the GFCI sensing would be defeated. There would be a line to ground shock potential between the energized load side line and ground , that is it GFCI would not operate.
With the white pigtail tied to the line side neutral if either line were to be open the GFCI would still operate.
However, for the GFCI to be able to provide GFCI protection with one line open and the neutral pigtail not connected to a line side neutral, a line to ground current from the energized line to ground must be sufficient to power the GFCI brains to trip the breaker.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: 2 Pole GFCI Breaker?
I have done some rethinking on this as I am in error with the newer fail-safe GFCI's on the market. And owe an apology to those who tried to correct me. as I have done some research into the newer units and they do pick up power from the neutral to power the LM1851 the IC that controls the operation of the GFCI tripping circuit. while it is not the actual neutral in a two pole GFCI breaker that is directly monitored to cause the GFCI to trip, But because the neutral supplies the full-wave rectifier that in turn supplies the LM1851 with out the neutral the breaker cannot be reset (fail-safe mode) this is also the same reason that the newer GFCI receptacles will not reset before power is applied to them. Some of my older books on GFCI's and how they work were based on the old way they worked and that was simply the current coil supplied the power that opened the relay that removed the power. the neutral was only for the test button to simulate a ground fault.
To my suprised I also found that they have incorporated a MOV along with other type's of filtering to improve the false tripping.
More can be read about it at:
All about the LM1851 And the GFCI
This is also the manufacture of the LM1851 IC Chip
[ November 10, 2003, 12:47 AM: Message edited by: hurk27 ]
I have done some rethinking on this as I am in error with the newer fail-safe GFCI's on the market. And owe an apology to those who tried to correct me. as I have done some research into the newer units and they do pick up power from the neutral to power the LM1851 the IC that controls the operation of the GFCI tripping circuit. while it is not the actual neutral in a two pole GFCI breaker that is directly monitored to cause the GFCI to trip, But because the neutral supplies the full-wave rectifier that in turn supplies the LM1851 with out the neutral the breaker cannot be reset (fail-safe mode) this is also the same reason that the newer GFCI receptacles will not reset before power is applied to them. Some of my older books on GFCI's and how they work were based on the old way they worked and that was simply the current coil supplied the power that opened the relay that removed the power. the neutral was only for the test button to simulate a ground fault.
To my suprised I also found that they have incorporated a MOV along with other type's of filtering to improve the false tripping.
More can be read about it at:
All about the LM1851 And the GFCI
This is also the manufacture of the LM1851 IC Chip
[ November 10, 2003, 12:47 AM: Message edited by: hurk27 ]
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