Double pole GFCI breaker

[dwellselectric]

I am trying to understand this and I was wondering if someone could please help explain it to me because I don't see how it can work properly. How does a double pole GFCI breaker work when no neutral is present?

 

[480sparky]

I am trying to understand this and I was wondering if someone could please help explain it to me because I don't see how it can work properly. How does a double pole GFCI breaker work when no neutral is present?

If the amperage on L1 is the same as on L2, then there's no leakage. If one is lower than the other, leakage is assumed and the trip mechanism is engaged.

 

[kbsparky]

Some 2-pole GFCI breakers have a neutral connection, some don't.

GFCI's work on the principle of monitoring current-carrying conductors -- as long as the values are equal, the circuit remains on. If one or more of the CCC's values' differ by more than 5 mA (or 30mA as is the case of Equipment protection) then the mechanism trips out the circuit.

By running all the CCC's through a CT, balanced circuits will cancel each other out, whether you are using a neutral conductor or not. The value read by the CT will always be -0-.

Once an imbalance manifests itself, the circuit is being completed elsewhere, and the breaker trips.

 

[dwellselectric]

Some 2-pole GFCI breakers have a neutral connection, some don't.

GFCI's work on the principle of monitoring current-carrying conductors -- as long as the values are equal, the circuit remains on. If one or more of the CCC's values' differ by more than 5 mA (or 30mA as is the case of Equipment protection) then the mechanism trips out the circuit.

By running all the CCC's through a CT, balanced circuits will cancel each other out, whether you are using a neutral conductor or not. The value read by the CT will always be -0-.

Once an imbalance manifests itself, the circuit is being completed elsewhere, and the breaker trips.

Thank you that was very helpful

 

[LarryFine]

A bit more detail:

Don't get confused by the common description that the GFCI senses the difference between the hot and neutral currents. It senses the differences among all of the conductors by passing all of the conductors through a ring with a small coil wrapped around it; a current transformer.

If any current goes through the ring but does not come back through it, a voltage developes on the small coil, and it's analyzed and amplified, and trips the device. For current to pass through and not return, it must leak to earth or another grounded surface, possibly through a body.

The electrical supply has to be grounded for the leakage current to want, and be able, to travel through the body, whatever it's in contact with, and to the grounded supply conductor. It's ironic: the grounding connection that makes the device necessary is also what enables it to function.

 

[quogueelectric]

A bit more detail:

Don't get confused by the common description that the GFCI senses the difference between the hot and neutral currents. It senses the differences among all of the conductors by passing all of the conductors through a ring with a small coil wrapped around it; a current transformer.

If any current goes through the ring but does not come back through it, a voltage developes on the small coil, and it's analyzed and amplified, and trips the device. For current to pass through and not return, it must leak to earth or another grounded surface, possibly through a body.

The electrical supply has to be grounded for the leakage current to want, and be able, to travel through the body, whatever it's in contact with, and to the grounded supply conductor. It's ironic: the grounding connection that makes the device necessary is also what enables it to function.

So you are saying that a gfci needs to be grounded to work properly???

 

[480sparky]

So you are saying that a gfci needs to be grounded to work properly???

No, the service & wiring system does.

But let's not go there any more, please.

 

[quogueelectric]

No, the service & wiring system does.

But let's not go there any more, please.

I was just bored but that is what he said.

 

[iwire]

So you are saying that a gfci needs to be grounded to work properly???

No, the service & wiring system does.

But let's not go there any more, please.

I was just bored but that is what he said.

No, he never said the "that a gfci needs to be grounded to work properly"

He said as Ken points out "the electrical supply has to be grounded"

 

[LarryFine]

Correct. What I said was:

The electrical supply has to be grounded . . .

In other words, one conductor of the supply system must be grounded, such as our typical grounded neutral.

The GFCI device needs no EGC to function; this is proven by GFCI breakers.

 

[hillbilly1]

Ground fault switchgears work on the same principles also, but the trip set point is much higher and adjustable (amps, instead of milliamps) And as with the Ground fault protection for individual equipment (30 milliamp trip) it is also designed to protect equipment, but on a larger scale, and normally high amperage services at higher voltages and available fault currents.