240v GFCI breaker vs inline GFCI?

[whoaru99]

Interesting.

When I had a 240V circuit brewing circuit added to my garage (Oregon, 2016), the inspector didn't flag lack of GFCI. Maybe he would've if the sink had already been installed.

I later bought an in-line GFCI based on HBT advice.

GFI requirement for 240V circuits came in 2020 NEC, then depending when adopted by your local authority.

 

[mac_1103]

Code is updated every three years, and local jurisdictions don't always start enforcing the latest update immediately. 2014 NFC would have been in effect for work done in 2016. Requirements were different three cycles ago.

 

[hotbeer]

I'm not an expert on the internals of a GFI breaker, but I thought the internal circuitry for the GFCI required the breaker as well.

With a GFCI breaker, everything on that circuit that is properly wired is protected by GFCI. You don't need a GFCI outlet when you use a GFCI breaker.

If the person you paid to wire wasn't a properly licensed electrician, I wouldn't use them and instead would just trust my own DIY. You wouldn't believe how many things I find that a few shoddy licensed electricians do that I'd never want to find being done in my home.

 

[whoaru99]

I'm not an expert on the internals of a GFI breaker, but I thought the internal circuitry for the GFCI required the breaker as well.

No, as evidenced by integral GFI receptacles that can be installed first in line and provide downstream GFI protection to non-GFI receptacles, all while fed from a non-GFI breaker.

Problem is I don't recall (yet?) seeing GFI receptacles for 240V circuits nor even higher-amp GFI receptacles for 120V circuits, rather than GFI function in a breaker.

 

[Langerz]

With a GFCI breaker, everything on that circuit that is properly wired is protected by GFCI. You don't need a GFCI outlet when you use a GFCI breaker.

If the person you paid to wire wasn't a properly licensed electrician, I wouldn't use them and instead would just trust my own DIY. You wouldn't believe how many things I find that a few shoddy licensed electricians do that I'd never want to find being done in my home.

I didn't mean a GFCI breaker. The directions on the Square D break I installed said the neutral pigtail needed to be connected for the GFCI portion of the breaker to work properly. I don't know if that was just standard warning verbiage so people connect it or actually required based on how that circuitry works.

 

[hotbeer]

Why wouldn't you connect the connect the curly wire as they said to do? The people that make these things tend to know what they are talking about. So you should follow their instructions.

If you had trouble finding a outlet that matches the plug for your 240v appliance, the one issue you might have had with getting a outlet for whatever that 240V appliance is that you wish to plug in, is that not all the types of 240v plugs have a GFCI outlet made for them. At least not one that is easily found or affordable. But a properly wired GFCI breaker gives any outlet on that circuit GFCI protection... assuming you connect all the outlet wires properly and it's a grounded outlet.

The plug configuration for many 240v appliances is based partly or maybe largely on their amperage requirements and whether they are 3 wire or 4 wire 240v. And to a lesser extent so are some plugs for 120v appliances.

 

[whoaru99]

I didn't mean a GFCI breaker. The directions on the Square D break I installed said the neutral pigtail needed to be connected for the GFCI portion of the breaker to work properly. I don't know if that was just standard warning verbiage so people connect it or actually required based on how that circuitry works.

It sounds like you're maybe trying to overthink it.

Meaning, it reads like you do have a GFI breaker but are trying to mentally separate the GFI function from the overcurrent protection function. And, yes, those are separate functions.

That said, there would be no reason not to make the Neutral connection to facilitate GFI on the line to neutral loads, even if you don't have any because there is no drawback to doing it. If you didn't intend to connect it that way there would be no point to pay the much higher cost of a GFI vs non-GFI breaker.

 

[whoaru99]

... is that not all the types of 240v plugs have a GFCI outlet made for them. At least not one that is easily found or affordable. assuming you connect all the outlet wires properly and it's a grounded outlet.

Hopefully this doesn't come across as too nit-picky, but the intended meaning of this isn't real clear to me.

So, I feel compelled to point out/clarify just in case, that function of GFI is not contingent on having a grounding wire.

 

[hotbeer]

So, I feel compelled to point out/clarify just in case, that function of GFI is not contingent on having a grounding wire.

I think for a 240v GFCI breaker, it must be connected to the neutral. But I admit I might be wrong since I'm not a electrician. Unlike the 120v, both the white and black wires are hot. How would it know if a ground fault existed if it doesn't have anything to compare to?

In a 120v circuit, the white wire is actually connected to the same neutral bus the ground wire is connected to. However the function of the ground wire adds additional safety. Though outside the realm of GFCI itself.

I suppose that maybe seeing a imbalance between the two line ins might provide a way. But I'm not going to rely on that. I'd hook everything up as it's shown in the diagram unless I meet any of the specific exceptions they might make for connecting it.

As well, I don't know if 240v is implemented the same in other countries that use 240v as their standard. I'm assuming the both of you are in the USA.

 

[whoaru99]

I think for a 240v GFCI breaker, it must be connected to the neutral. But I admit I might be wrong since I'm not a electrician. Unlike the 120v, both the white and black wires are hot. How would it know if a ground fault existed if it doesn't have anything to compare to?

A 240V double-pole GFI breaker includes the neutral for reference of current imbalance/leakage for 120V line to neutral loads that may be served by that breaker, whilst the 240V loads are gfi protected by monitoring current imbalance/leakage line to line.

 

[Skeeter686]

A 240V double-pole GFI breaker includes the neutral for reference of current imbalance/leakage for 120V line to neutral loads that may be served by that breaker, whilst the 240V loads are gfi protected by monitoring current imbalance/leakage line to line.

I did not know that. So, for 240V, it's not comparing neutral vs. ground, but but between the two "hot" lines?

Wondering because I was just lucky enough to have had a new outlet installed, and the GFI was apparently defective out of the box. So, now I'm curious how they work.

 

[whoaru99]

In a 120v circuit, the white wire is actually connected to the same neutral bus the ground wire is connected to. However the function of the ground wire adds additional safety. Though outside the realm of GFCI itself.

Indeed, but one should never equate their functions. "Neutral" is or can be current carrying conductor in normal operation. The equipment ground should never carry current except in case of a fault. That is the prime purpose of equipment ground, to provide a low resistance path for fault current to provide for quick tripping of the overcurrent protection.

 

[Langerz]

Why wouldn't you connect the connect the curly wire as they said to do? The people that make these things tend to know what they are talking about. So you should follow their instructions.

If you had trouble finding a outlet that matches the plug for your 240v appliance, the one issue you might have had with getting a outlet for whatever that 240V appliance is that you wish to plug in, is that not all the types of 240v plugs have a GFCI outlet made for them. At least not one that is easily found or affordable. But a properly wired GFCI breaker gives any outlet on that circuit GFCI protection... assuming you connect all the outlet wires properly and it's a grounded outlet.

The plug configuration for many 240v appliances is based partly or maybe largely on their amperage requirements and whether they are 3 wire or 4 wire 240v. And to a lesser extent so are some plugs for 120v appliances.

It sounds like you're maybe trying to overthink it.

Meaning, it reads like you do have a GFI breaker but are trying to mentally separate the GFI function from the overcurrent protection function. And, yes, those are separate functions.

That said, there would be no reason not to make the Neutral connection to facilitate GFI on the line to neutral loads, even if you don't have any because there is no drawback to doing it. If you didn't intend to connect it that way there would be no point to pay the much higher cost of a GFI vs non-GFI breaker.

I’ll withdraw my question because I don’t think I asked it well. I hooked up the neutral pigtail. I agreed there is no reason not to. My question was trying to understand how the internals of the gfi breaker works and if that portion required the pigtail. It was just a curiosity question on the operation of the breaker and I would have connected it either way

The question was answered later in that it’s required when there is a 120 v lines that may be served which makes sense and was all I was looking for

 

[doug293cz]

I didn't mean a GFCI breaker. The directions on the Square D break I installed said the neutral pigtail needed to be connected for the GFCI portion of the breaker to work properly. I don't know if that was just standard warning verbiage so people connect it or actually required based on how that circuitry works.

Proper operation includes the correct operation of the "Test" button, which verifies that the GFCI will trip on a ~5mA outgoing vs. return current imbalance. Depending on the internal design of the GFCI, the neutral connection may be required in order for the "Test" function to work properly. Connect the GFCI breaker according to instructions, whether you have 120V loads serviced by the circuit. or not.

Hopefully this doesn't come across as too nit-picky, but the intended meaning of this isn't real clear to me.

So, I feel compelled to point out/clarify just in case, that function of GFI is not contingent on having a grounding wire.

Again, depending on the design of the GFCI, it might require the ground to be connected in order for the "Test" function to work. You don't need the ground for the leakage detection to work as intended, but if you can't test the trip threshold, you won't know if the GFCI will trip when it should.

A 240V double-pole GFI breaker includes the neutral for reference of current imbalance/leakage for 120V line to neutral loads that may be served by that breaker, whilst the 240V loads are gfi protected by monitoring current imbalance/leakage line to line.

A USA 240V GFCI breaker monitors currents in the two hots and the neutral as an aggregate. All three wires go thru the current sensing coil. As an example, if a load has 18A of 240V draw, and 2A of 120V draw, then one hot will carry 20A, the other hot will carry 18A, and the neutral will carry 2A. The direction of flow of the 20A hot will be the opposite of the direction in the 18A hot and the neutral. So the "vector sum" of the of the currents is zero. If there are no 120V loads, then the two hots carry the same current, and the neutral carries 0 current.

I did not know that. So, for 240V, it's not comparing neutral vs. ground, but but between the two "hot" lines?

Wondering because I was just lucky enough to have had a new outlet installed, and the GFI was apparently defective out of the box. So, now I'm curious how they work.

Indeed, but one should never equate their functions. "Neutral" is or can be current carrying conductor in normal operation. The equipment ground should never carry current except in case of a fault. That is the prime purpose of equipment ground, to provide a low resistance path for fault current to provide for quick tripping of the overcurrent protection.

As stated above, the ground is not compared to anything in the GFCI, but may be required for the "Test" function to work correctly.

Brew on

 

[Langerz]

Proper operation includes the correct operation of the "Test" button, which verifies that the GFCI will trip on a ~5mA outgoing vs. return current imbalance. Depending on the internal design of the GFCI, the neutral connection may be required in order for the "Test" function to work properly. Connect the GFCI breaker according to instructions, whether you have 120V loads serviced by the circuit. or not.



Again, depending on the design of the GFCI, it might require the ground to be connected in order for the "Test" function to work. You don't need the ground for the leakage detection to work as intended, but if you can't test the trip threshold, you won't know if the GFCI will trip when it should.



A USA 240V GFCI breaker monitors currents in the two hots and the neutral as an aggregate. All three wires go thru the current sensing coil. As an example, if a load has 18A of 240V draw, and 2A of 120V draw, then one hot will carry 20A, the other hot will carry 18A, and the neutral will carry 2A. The direction of flow of the 20A hot will be the opposite of the direction in the 18A hot and the neutral. So the "vector sum" of the of the currents is zero. If there are no 120V loads, then the two hots carry the same current, and the neutral carries 0 current.





As stated above, the ground is not compared to anything in the GFCI, but may be required for the "Test" function to work correctly.

Brew on

Awesome description. I understand now. Thanks for the post