Boat lift question

[kwired]

They chose to place the test current resistor from neutral to one phase so that they could use the same button and resistor value that they use for the single pole units. There is no reason they could not have used a resistor with twice the ohm value and twice the power rating and connected it between L1 and L2. But they did what they did. So it is a manufacturers' decision rather than a physical law that requires the neutral pigtail connection.
And of course if there is a current carrying neutral to the load, it must pass through the current coil in the GFCI. That part is a physical law.
I cannot find any fault in your use of "typically" since it is hard to get more typical than SquareD.

Besides the "test feature" not working the remaining question is whether or not everything else still works with no neutral. I really have no clue, I guess it would depend on how the control circuitry works. Next question is does it still work if one of the ungrounded conductors is open ahead of the device?

 

[GoldDigger]

Besides the "test feature" not working the remaining question is whether or not everything else still works with no neutral. I really have no clue, I guess it would depend on how the control circuitry works. Next question is does it still work if one of the ungrounded conductors is open ahead of the device?

If one of the ungrounded conductors is open upstream, either there will be no current on that phase wire at all or current that would normally be on that phase wire at a load will return through other loads and then via one of the other phase wires or the neutral. Just like in a 120/240 MWBC with an open phase line. As long as no current returns to ground instead of the remaining conductors the GFCI will still see a current balance. If any current flows to ground, the GFCI will trip regardless of which phase conductor it originated on.

Based only on the fact that the partial schematic shows a single current coil, it should not matter to the operation of the GFCI breaker, but there is the unknown factor of where the power to the black box circuit board is derived from.
If it also is obtained only from one of the two lines to Neutral, then it will probably fail to work at all, and if you are lucky would not even hold in when reset.

 

[kwired]

If one of the ungrounded conductors is open upstream, either there will be no current on that phase wire at all or current that would normally be on that phase wire at a load will return through other loads and then via one of the other phase wires or the neutral. Just like in a 120/240 MWBC with an open phase line. As long as no current returns to ground instead of the remaining conductors the GFCI will still see a current balance. If any current flows to ground, the GFCI will trip regardless of which phase conductor it originated on.

Based only on the fact that the partial schematic shows a single current coil, it should not matter to the operation of the GFCI breaker, but there is the unknown factor of where the power to the black box circuit board is derived from.
If it also is obtained only from one of the two lines to Neutral, then it will probably fail to work at all, and if you are lucky would not even hold in when reset.[/QUOTE

I understand that, my question is does the so called "processor" work if one or other ungrounded and/or the grounded conductor becomes open? The sensing coil may see imbalance but if control voltage is not there to trip the device it is possible that it doesn't trip anyway. It all depends on just exactly how this device works, and something I do not really know anything about.

 

[GoldDigger]

I understand that, my question is does the so called "processor" work if one or other ungrounded and/or the grounded conductor becomes open? The sensing coil may see imbalance but if control voltage is not there to trip the device it is possible that it doesn't trip anyway. It all depends on just exactly how this device works, and something I do not really know anything about.

If the electronics take their power from one of the two lines only, then it would be as if there were no power to the breaker at all. By design the breaker would not reset under those conditions, but whether or not it would open if already set is a design decision. GFCI receptacles (in US anyway) are designed to continue to hold on loss of power, since we don't want to go around resetting receptacles every time the power fails.
GFCI receptacles used as part of portable cord sets, such as for construction work, are designed the opposite way. They will open on loss of power and then have to be manually reset when the power is back on. I guess the idea is to avoid a situation where the GFCI can deliver a burst of energy when the circuit power is restored, even if there is already a ground fault that was created while the power is off?
Or maybe just to force/encourage the user to test them every time they are used?

 

[kwired]

If the electronics take their power from one of the two lines only, then it would be as if there were no power to the breaker at all. By design the breaker would not reset under those conditions, but whether or not it would open if already set is a design decision. GFCI receptacles (in US anyway) are designed to continue to hold on loss of power, since we don't want to go around resetting receptacles every time the power fails.
GFCI receptacles used as part of portable cord sets, such as for construction work, are designed the opposite way. They will open on loss of power and then have to be manually reset when the power is back on. I guess the idea is to avoid a situation where the GFCI can deliver a burst of energy when the circuit power is restored, even if there is already a ground fault that was created while the power is off?
Or maybe just to force/encourage the user to test them every time they are used?

So is there a loss of GFCI protection if the right supply conductor(s) is lost? Especially with a 2 pole breaker?

 

[Tbizzelmd]

 

[GoldDigger]

So is there a loss of GFCI protection if the right supply conductor(s) is lost? Especially with a 2 pole breaker?

I expect there would be, unless the two pole breaker is specifically designed around that possibility. Maybe that is another reason they need a neutral, so you can rectify working power for the circuit from either phase alone to the neutral.
But if they really make a two pole breaker by putting a common trip "normal" breaker section next to same mechanism as used in a single pole GFCI breaker (and run the extra wire through that same coil, it may make a difference which hot you lose.

 

[kwired]

I expect there would be, unless the two pole breaker is specifically designed around that possibility. Maybe that is another reason they need a neutral, so you can rectify working power for the circuit from either phase alone to the neutral.
But if they really make a two pole breaker by putting a common trip "normal" breaker section next to same mechanism as used in a single pole GFCI breaker (and run the extra wire through that same coil, it may make a difference which hot you lose.

I don't exactly how they work myself, but kind of was hoping that if you lost a supply conductor you would still have protection - especially if sitting in your hot tub or swimming pool, but maybe the only way to do that is for the device to drop out if proper voltage is not present - like the cord end type units do.

 

[Little Bill]

2-pole GFCI breakers do not require a neutral to work. You do connect the pigtail to the neutral bar, but don't have to land a neutral on the breaker for it to work.

 

[kwired]

2-pole GFCI breakers do not require a neutral to work. You do connect the pigtail to the neutral bar, but don't have to land a neutral on the breaker for it to work.

Most of us know you do not have to have a load side neutral for it to work. What golddigger and myself have been debating is whether or not you must have the supply side neutral connected in order for it to work.

I have always thought you must have supply side neutral or it will not work properly, but it has been suggested you may not need it, but has not been proven either.

 

[Little Bill]

Most of us know you do not have to have a load side neutral for it to work. What golddigger and myself have been debating is whether or not you must have the supply side neutral connected in order for it to work.

I have always thought you must have supply side neutral or it will not work properly, but it has been suggested you may not need it, but has not been proven either.

I'm pretty sure the pigtail has to land on the neutral bus (actually 100% sure). I think any imbalance or leak will go through the neutral and the GFCI will since an imbalance and trip. I'm fairly certain if you don't connect the pigtail to the neutral bus the GFCI will never close. Kind of like when you have the line/load reversed on a GFCI receptacle.

from a spa spec sheet

Providing Therapy for Life
15
For help, please call
877-722-4097
From Main Power Supply to GFCI
From GFCI to Spa Controls
Important!!
The white neutral wire from the back
of the GFCI
MUST
be connected to
an incoming service neutral. The
GFCI will not work without it. If the
incoming white neutral wire is not
properly connected, the GFCI will
automatically trip. If the GFCI trips
when you power on the spa, you
should make sure the neutral wire is
properly connected

 

[kwired]

I'm pretty sure the pigtail has to land on the neutral bus (actually 100% sure). I think any imbalance or leak will go through the neutral and the GFCI will since an imbalance and trip. I'm fairly certain if you don't connect the pigtail to the neutral bus the GFCI will never close. Kind of like when you have the line/load reversed on a GFCI receptacle.

Imbalance does not have to have the neutral in order to happen. Any current that leaves the GFCI but does not come back to the GFCI via one of the protected conductors is the imbalance the device is looking for in order to cause it to trip. This alternate path for imbalance can be anything. The question is whether or not the neutral as well as both "hot conductors" on a double pole unit is necessary to power the logic component that analyzes the current balance and operates the trip mechanism?

 

[Little Bill]

Imbalance does not have to have the neutral in order to happen. Any current that leaves the GFCI but does not come back to the GFCI via one of the protected conductors is the imbalance the device is looking for in order to cause it to trip. This alternate path for imbalance can be anything. The question is whether or not the neutral as well as both "hot conductors" on a double pole unit is necessary to power the logic component that analyzes the current balance and operates the trip mechanism?

See my edited post!

 

[kwired]

See my edited post!

No fair making changes after someone comments

What kind of GFCI device is being referred to in that material?

I kind of always assumed that the supply side neutral is required for the device to function properly. Not certain that your average GFCI circuit breaker will trip with no supply neutral though. Remember it is monitoring L1, L2, and N. Loss of incoming L1, L2, or N is not a ground fault, so the device may not need to be designed to detect presence of those. However specific units may be designed to check for presence of all three of those, like a unit designed specifically for a spa, or for protective devices that are a part of portable cord and plug equipment, the risk of loss of a conductor is not as great with a hard wired device as it is for a cord and plug supplied device.

 

[Little Bill]

No fair making changes after someone comments

What kind of GFCI device is being referred to in that material?

I kind of always assumed that the supply side neutral is required for the device to function properly. Not certain that your average GFCI circuit breaker will trip with no supply neutral though. Remember it is monitoring L1, L2, and N. Loss of incoming L1, L2, or N is not a ground fault, so the device may not need to be designed to detect presence of those. However specific units may be designed to check for presence of all three of those, like a unit designed specifically for a spa, or for protective devices that are a part of portable cord and plug equipment, the risk of loss of a conductor is not as great with a hard wired device as it is for a cord and plug supplied device.

It is for a standard 2-pole 240V GFCI. You can buy spa disconnects with a 50A GFCI breaker in them, but the GFCI is not unique to the disconnect. It is the same as a stand alone GFCI. I know this because I was looking for a 50A GFCI for a C/H and couldn't find it locally at the time. I bought the disconnect and saw that the breaker was the same. Funny part is you can buy the disconnect with the breaker cheaper than you can buy just the breaker at some places.

I just happened to be looking over the specs for a spa install I am doing this week and saw this thread.

In one of the drawings, I saw the picture was from Sq D.