using a GFCI as a shunt trip, how creative?

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480sparky said:
But the 1900 box instructions don't prohibit it.
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Right. Which is why I asked if it was the only part of code you knew when you asked the question. 110.3(B) does not stop you from burying 1900 boxes in your yard. So if 110.3(B) is the only part of code you were looking at, then the answer would be "yes", you can bury your 1900 boxes in the yard. If 110.3(B) is the only part of code you were looking at, there is no prohibition for the OP's condition either.

The point, is that if it is not permitted, it is not because it fails 110.3(B). If anything, it would fail under the possible reasons that Volta provided.

Volta said:
'Course, we need to know what version was in effect when this was installed, per 2011 you could call it on:

200.4 Neutral conductors shall not be used for more than one branch circuit, for more than one multiwire branch circuit, or for more than one set of ungrounded feeder conductors unless specifically permitted elsewhere in this Code.
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This doesn't apply because it is not a separate circuit.

Volta said:
250.24(A)(5) Load-Side Grounding Connections. A grounded conductor shall not be connected to normally non?currentcarrying metal parts of equipment, to equipment grounding conductor(s), or be reconnected to ground on the load side of the service disconnecting means except as otherwise permitted in this article.
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This one may be applicable, but it is still a little iffy. The grounded conductor is not connected to the grounding system--it is connected to a switch that transfers it to the grounding system.

Volta said:
300.20(A) Conductors Grouped Together. Where conductors carrying alternating current are installed in ferrous metal enclosures or ferrous metal raceways, they shall be arranged so as to avoid heating the surrounding ferrous metal by induction. To accomplish this, all phase conductors and, where used, the grounded conductor and all equipment grounding conductors shall be grouped together.
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This also is not applicable, because inductive heating is not applicable, nor is this a conductor that is carrying current. When it's open circuit, no current flows. When it's closed, the supply is interrupted. So if anything, this conductor would be classified as a control wire.
 
buddhakii said:
This shunt trip set up wouldn't work too well if there was no load on the circuit.
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This is not true, a UL listed GFCI will funtion on a grounded neutral without any load placed upon the GFCI as I posted about this at the end of post 17.

Take a look at this Code Check publication by Sam Goldwasser who was the creator of "Sam's Facts" which provided electronic circuit diagrams for the electronic repair industry for many years:

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The Grounded Neutral check (second induction coil) was added at some point and is the current GFCI standard. It was not part of earlier GFCIs (not sure what year they were introduced).

Way back I worked in designing Semiconductor processing equipment. We had a Heat Control Unit that fed chemical bath heaters. Semiconductor Industry standards required GFI protection on these baths. We took advantage of this fact for another function. We monitored the heat pulse control circuit - when the control was turned off.

If the output relays were still closed (indicating welded contacts) and still supplying power to the heaters, when the control was off, we purposely grounded the output via a current limiting resistor. This then tripped the GFI. This saved us a shunt trip since the GFI had to be there anyways.
We had no problem getting third party approvals for that circuit.
 
hurk27 said:
This is not true, a UL listed GFCI will funtion on a grounded neutral without any load placed upon the GFCI as I posted about this at the end of post 17.

Take a look at this Code Check publication by Sam Goldwasser who was the creator of "Sam's Facts" which provided electronic circuit diagrams for the electronic repair industry for many years:

You must have Adobe Acrobat installed to open it
Click to expand...

Just when I thought I new everything I get humbled. Seriously though, thanks for the correction. The more I know I find I don't know s***.
 
hurk27 said:
This is not true, a UL listed GFCI will funtion on a grounded neutral without any load placed upon the GFCI as I posted about this at the end of post 17.

Take a look at this Code Check publication by Sam Goldwasser who was the creator of "Sam's Facts" which provided electronic circuit diagrams for the electronic repair industry for many years:

You must have Adobe Acrobat installed to open it
Click to expand...

You meant to say a GFCI will NOT function with a grounded neutral, even with no load applied. Right?
 
ELA said:
The Grounded Neutral check (second induction coil) was added at some point and is the current GFCI standard. It was not part of earlier GFCIs (not sure what year they were introduced).
Way back I worked in designing Semiconductor processing equipment. We had a Heat Control Unit that fed chemical bath heaters. Semiconductor Industry standards required GFI protection on these baths. We took advantage of this fact for another function. We monitored the heat pulse control circuit - when the control was turned off.

If the output relays were still closed (indicating welded contacts) and still supplying power to the heaters, when the control was off, we purposely grounded the output via a current limiting resistor. This then tripped the GFI. This saved us a shunt trip since the GFI had to be there anyways.
We had no problem getting third party approvals for that circuit.
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answer to above in red:

The second 120hz coil was added somewhere in the "90's" actully this 120hz coil is the first coil and the detect coil is the second coil circuit wise.
 
hurk27 said:
answer to above in red:

The second 120hz coil was added somewhere in the "90's" actully this 120hz coil is the first coil and the detect coil is the second coil circuit wise.
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As shown in the fig 2 (schematic) of the LM1851 data sheet, with respect to the load I take it you mean?
 
ELA said:
As shown in the fig 2 (schematic) of the LM1851 data sheet, with respect to the load I take it you mean?
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Yes supply is from the left then the 120hz coil (neutral to ground trip) then the H/G coil (hot to ground trip) then the load.

As it says in the article:
To detect a Neutral to Ground fault there is a second transformer (left toroid in the illustration below) placed upstream
of the H-G sense transformer (in the illustration above). A small drive signal is injected via the 200 T winding which
induces equal voltages on the H and N wires passing through its core.
If
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