criteria regarding selecting GFI breaker number of poles?

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mustafa

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I hae three types of loads (hotplate,boiler,socket) all of them is three phase with neutral, system voltage is 400
 

kwired

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I hae three types of loads (hotplate,boiler,socket) all of them is three phase with neutral, system voltage is 400
Not your typical loads that require GFCI from the NEC, but not impossible to protect with GFCI either, though you may need a stand alone device instead of a circuit breaker that incorporates the protection.

Number of poles? I guess the number itself it depends on exactly how you define what a pole is. Physically you need one "pole" for every circuit conductor including the neutral if you have one in your circuit, this is required by design/function of the device.
 

GoldDigger

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If you have a wye supply, three wired plus neutral, you need a GFCI which interrupts three wires based in the current balance over all four wires. We would normally call this a three pile GFCI. Just as we call a GFCI which interrupts one wire based on the current balance over two wires is called a single pole.
 

GoldDigger

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just to confirm

Three or four pole is required in star connection?
Three poles, with a fourth paid of terminals or pigtail and terminal and pigtail for the neutral to pass through.
I have not seen anything I would call a four pole GFCI, although I suppose you could use such a device with five wire two phase power (four hots and a neutral)
 

kwired

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Typical GFCI devices monitor and interrupt grounded as well as ungrounded conductors of the circuit. A circuit breaker type GFCI typically will not have overcurrent protection in the neutral but still opens the neutral when it trips.
 

mustafa

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i found this from wikipedia

[h=3]Number of poles[/h]RCDs may comprise two poles for use on single phase AC supplies (two current paths), three poles for use on three phase AC supplies (three current paths) or four poles for use on three phase & neutral supplies. Specially designed RCDs can also be used with both AC and DC power distribution systems.
 

GoldDigger

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i found this from wikipedia

[h=3]Number of poles[/h]RCDs may comprise two poles for use on single phase AC supplies (two current paths), three poles for use on three phase AC supplies (three current paths) or four poles for use on three phase & neutral supplies. Specially designed RCDs can also be used with both AC and DC power distribution systems.
1. RCDs are generally used with European style distributions which do not have the center tapped single phase as in the US. This includes the occasional country with an ungrounded system that requires a contact for both wires of a two wire circuit.
2. A US GFI for a 220V load, with or without the neutral being used also, would be a two pole device. For the mist part US GFCI breakers do not interrupt the neutral, so it would not require a pole.
 

kwired

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For the mist part US GFCI breakers do not interrupt the neutral, so it would not require a pole.

Guess I have not checked that out so I am not sure. I can't recall any GFCI receptacles that do not open both lines, and I guess I kind of assumed circuit breaker GFCI's likely did the same. If you have a fault from another circuit returning via GFCI protected neutral, you will trip the device, but if the neutral is not opened you still have fault current - there is both good and bad in that situation I guess depending on the application.
 

GoldDigger

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Guess I have not checked that out so I am not sure. I can't recall any GFCI receptacles that do not open both lines, and I guess I kind of assumed circuit breaker GFCI's likely did the same. If you have a fault from another circuit returning via GFCI protected neutral, you will trip the device, but if the neutral is not opened you still have fault current - there is both good and bad in that situation I guess depending on the application.
I am going by word of mouth and the absence of a third pole space to deduce that the neutral is not interrupted at a typical GFCI breaker.
 

kwired

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Location
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I am going by word of mouth and the absence of a third pole space to deduce that the neutral is not interrupted at a typical GFCI breaker.
Now you are going to make me go test one - if I remember this when I next see one. I may get that chance today, will try to remember and report what I found.
 
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